THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID VEGETABLE PHYSIOLOGY SYSTEMATIC BOTANY: BY WILLIAM B.J3ARPENTER, M.D., F.R.S., F.G.S., AUTHOR OF "PRINC1>I.P.S OP GENERAL AND COMPARATIVE PH YSTOI.OOV," AND OF Ncfo antr ISnlargetr Siftfon. LONDON: WAT. S. ORR AND Co., PATERNOSTER ROW. MDCCCXLVIII. C3 PREFACE. THE object of the following Treatise is to communicate such a general view of the structure and growth of plants, and of their natural classification, as should be at the same time popular in its form and scientific in its principles. The botanist has too frequently concerned himself, almost or quite exclusively, about the collection of specimens, the examination of their external characters, and the deter- mination of their names ; all the wonders and beauties of their internal structure, and the interest derivable from the observation of the uses of their several parts or organs, being very commonly overlooked. It is not among the least of the advantages of the natural system of classi- fication, that, as its divisions are founded upon corres- pondences and differences in internal conformation, in- stead of being based upon external characters only, the general adoption of it has necessarily caused much more attention to be paid to the organization of plants ; and this has naturally led to increased observation of their functions and habits of life, to the study of the conditions on which their growth and propagation are dependent, M363816 VI PREFACE. and to the application of the knowledge thus acquired to the improvement of the art of cultivation, whether in the field, the garden, or the hothouse. The first part of the following volume is, therefore, devoted to an exposition of this part of Botanical science ; and the Author has endeavoured to state in the Introduc- tion some of the inducements which may incite to the study of it. He may here remark, in addition, that the progress of science is continually rendering closer and closer that relation between the physiology of plants and that of animals, which it was the Author's intention to develope, in his " Principles of General and Compara- tive Physiology," first published in 1838. It had long been admitted, that the physiology of man cannot be properly understood, unless studied in connection with that of the lower animals; and the truth, that the physiology of animals cannot be properly understood, unless it be studied in connection with that of plants, is now becoming generally recognized. Those who shall peruse the Treatise on Animal Physiology in this series, after they have made themselves acquainted with the first part of the following volume, will not find it difficult to perceive the connection here referred to. With regard to the portion of the volume devoted to PREFACE. Vll Systematic Botany, the author would remark,, that the reasons which have induced him to prefer the Natural System to the Linnsean, the latter having been hitherto almost universally employed in elementary treatises on Botany will be found fully stated in Chapter XIII. He has not aimed to give an account of every order, since this would have been of very little use to the beginner. In making a selection, he has regarded those as having the best claim to notice, which contain plants of the greatest importance to man, or which present some re- markable peculiarities of structure or habit ; a few have been introduced, however, which possess neither of these distinctions, either as containing well-known British plants, or on account of their great abundance in parti- cular spots of the globe. The Cryptogamia have not been treated of in this, division of the work, since a general view of their chief groups is contained in Chapter II., and further details would not have possessed sufficient interest for the unscientific reader. For various reasons, he has thought it best to adopt the system of De Candolle, as being the one most in use at the present time ; but he has derived great assistance from the systematic works of Dr. Lindley, and especially from the useful but expensive " Ladies' Botany " of that Vlll PREFACE. author, which he would strongly recommend to such of his readers as can gain access to it. He would remark, in conclusion, that any systematic Treatise like the present must consist, in great part, of materials collected by other naturalists ; and that the merit of an elementary work must consist rather in the judgment shown in the selec- tion and arrangement of the materials, than in the origi- nality of its contents. How far he has succeeded in his present attempt, it will be for his readers to decide. ADVERTISEMENT. THE object of the following Treatise is to communicate a popular, but at the same time a scientific, view of the chief tribes of Flowering Plants, arranged according to the Natural System. The Author is not aware that any similar attempt has been heretofore made, to embody this arrangement in a work of a strictly elementary character, excepting in the useful but expensive "Ladies' Botany" of Dr. Lindley, which he would strongly recommend to such of his readers as can gain access to it. Being persuaded, however, that through the aid of this System alone can any definite idea be gained, of the vast extent and varied aspect of the Vegetable Kingdom, he has not hesitated to employ it here. In his selection of Orders, he has regarded those as having the best claim to notice, which contain plants of greatest importance to Man, or which present some remarkable peculiarities of structure or habit; a few, however, which possess neither of these distinctions, have been intro- duced, as containing well-known British plants, or on account of their great abundance in particular spots of the globe. The Cryptogamia have not been treated of in this Part, since a popular view of their character was included in the former one ; and further details would not have possessed sufficient genera 1 interest. W. B. C. CONTENTS TO VEGETABLE PHYSIOLOGY. INTRODUCTION CHAPTER I. OF THE GENERAL CHARACTERS OF LIVING BEINGS, AND THE DISTINC- TION BETWEEN ANIMALS AND VEGETABLES . . . .15 CHAPTER II. GENERAL VIEW OF THE VEGETABLE KINGDOM .... 21 CHAPTER III. OF THE ELEMENTARY STRUCTURE OF PLANTS . 58 CHAPTER IV. STRUCTURE AND FUNCTIONS OF THE ROOTS 78 CHAPTER V. OF THE STRUCTURE AND FUNCTIONS OF THE STEM .... 90 CHAPTER VI. OF THE FOOD OF PLANTS, AND THE MANNER IN WHICH IT IS OBTAINED 112 CONTENTS. CHAPTER VII. PAGE OF THE STRUCTURE OF LEAVES . . 145 CHAPTER VIII. OF THE FUNCTIONS OF LEAVES . . . . . . .167 EXHALATION 168 ABSORPTION OF FLUID BY THE LEAVES . . . ' . . 177 ON RESPIRATION . . . . . . . 183 FIXATION OF CARBON .186 INFLUENCE OF VEGETATION ON THE ATMOSPHERE . . 189 RETURN OF THE ELABORATED SAP 192 DEVELOPMENT AND DEATH OF LEAVES 193 CHAPTER IX. GENERAL REVIEW OF THE NUTRITIVE PROCESSES IN PLANTS . . 202 CHAPTER X. OP THE SECRETIONS OF PLANTS . . . . . . . 225 CHAPTER XI. OF THE PRODUCTION OF LIGHT, HEAT, AND ELECTRICITY BY PLANTS 260 OF THE MOTIONS OF PLANTS 265 CHAPTER XII. OF THE REPRODUCTION OF PLANTS . . . . . .271 ADDENDUM ,311 CONTENTS TO BOTANY. INTRODUCTORY CHAPTER. General Principles of Classification. Principles of Natural and Artificial Arrangements. Linnaean System. De Candolle's System ,.313 CLASS I. EXOGENS. SUB-CLASS I. THALAMIFLOK.E. Order Ranunculacea?, or Crow-foot Tribe Anemone, Hellebore, Monks- hood, &c. ..... 349 Magnoliacese, or Magnolia Tribe . . . 355 Anonacese, or Custard-Apple Tribe .... 358 Menispermacese, or Cocculus Tribe . . . . . 353 Berberidese, or Berberry Tribe 359 Nympbacese, or Water-Lily Tribe Victoria regalis, &c. . . 360 Fumariaceae, or Fumitory Tribe .... 362 Papaveraceao, or Poppy Tribe Celandine, &c. Opium . . . 363 Cruciferse, or Turnip Tribe Cabbage, Mustard, Stock, Scurvy- grass, &c 367 Cistacese, or Rock-Rose Tribe 373 Violacese, or Violet Tribe Pansy, &c 374 Droseraceae, or Sum-dew Tribe .... 375 Caryophyllese, or Chick-weed Tribe Pink, Carnation, Ragged- Robin, &c. ..... 377 Linacese, or Flax Tribe 379 Malvaceae, or Mallow Tribe Cotton . . . 333 Bombaceae, or Silk-Cotton Tribe Baobab ... 387 VI CONTENTS. PAGE Order Bromaceae, or Cacao Tribe 389 Tiliacese, or Linden Tribe Lime 391 Dipterocarpese, or Camphor-tree Tribe 393 Camelliacese, or Camellia Tribe Tea 393 Aurantiaeeae, or Orange Tribe Lemon, Shaddock, &c. . . 397 Ampelidese, or Grape Tribe Virginian Creeper, Zante Currant, &c. 402 Geraniaceae, or Geranium Tribe Cranesbill, Herb-Robert . . 407 Tropaeoleae, or Sturtion Tribe 410 Balsatninese, or Balsam Tribe 411 Oxalideze, or Wood-Sorrel Tribe ...... 412 Rutaceae, or Rue Tribe Fraxinella 413 Analytical Table 415 SUB-CLASS II. CALICIFLOR-E. Order Celastrineae, or Holly Tribe Brazilian Tea, Spindle-tree . . 417 Rhamnese, or Buckthorn Tribe Jujube, Lotus . . . 418 Terebintacese, or Terebinth Tribe Cashew-nut, Mango, Gum Mastic 420 Leguminosas, or Pea Tribe Bean, Clover, Senna, Tamarind, Mimosa, &c. ......... 422 Rosaceae, or Rose Tribe Apple, Strawberry, Raspberry, Almond, Medlar, &c 426 Rhizophoreae, or Mangrove Tribe 430 Onagrariaceae, or Evening. Primrose Tribe Willow-Herb, Fuchsia, &c 432 Myrtacese, or Myrtle Tribe Clove, Pomegranate, &c. . . 433 Cucurbitaceae, or Gourd Tribe Melon, Cucumber, Calabash, &c. 436 Passifloreae, or Passion-flower Tribe Grenadilla, &c. . . 438 Crassulacese, or HouseleeTc Tribe Sedum, &c 441 Cactese, or Prickly. Pear Tribe Indian Fig, Night-flowering Cereus, &c 442 Grossulariae, or Gooseberry Tribe Currant, &c 445 Saxifragese, or Saxifrage Tribe London Pride, Hydrangea, &c. 447 Umbelliferae, or Umbelliferous Plants Carrot, Parsnep, Celery, Hemlock, Parsley, &c 449 Loranthaceae, or Misseltoe Tribe. 452 Caprifoliaceae, or Honeysuckle Tribe Elder, Guelder Rose, Lau- restinus, &c 453 CONTENTS. Vii PAGE Order Compositae, or Composite Plants Daisy, Sun-flower, Asters, Thistle, Dahlia, &c 458 CampanulaceaB, or Hairbell Tribe 465 Lobeliacese, or Lobelia Tribe . . . . . . .467 Ericineae, or Heath, Tribe Rhododendron, Kalmia, Azalea, &c. . 469 Analytical Table 470 SUB-CLASS III. COROLLIFLOR^. Order Prinmlaceae, or Primrose Tribe Primrose, Cowslip, Polyan- thus, &c 471 Oleacese, or Olive Tribe Ash, Lilac, Privet, &c 472 Jasmineae, or Jessamine Tribe . . . . . . .475 Gentianese, or Gentian Tribe Centaury . . . . . 475 Convolvulaceae, or Bindweed Tribe Jalap, Scamraony Dodder, &c. 476 Labiate, or Labiate Plants Mint, Sage, Rosemary, &c. . . 478 Boragineae, or Borage Tribe Forget-me-not, Comfrey . . . 479 Solaneae, or Nightshade Tribe Henbane, Tobacco, Potato, &e. . 480 Scrophularineae, or Foxglove Tribe Snapdragon, Figwort, Speed- well, &c 485 Analytical Table 487 SUB-CLASS IV. MONOCHLAMYDE^;. Order Chenopodeae, or Goosefoot Tribe Spinage, Beet, Rhubarb, Buck- wheat, &c 488 Laurinese, or Laurel Tribe Cinnamon, Nutmeg, &c. . . . 490 Euphorbiacese, or Spurge Tribe Castor-oil, Cassava, Manchi- neel, &c. 493 Urticeae, or Nettle Tribe Fig, Bread-fruit, Hemp, Mulberry, Hop, &c 495 Piperaceaa, or Pepper Tribe 499 Amentaceae, or Catkin Tribe Oak, Beech, Hazel, Elm, Poplar, &c. 500 Coniferae, or Pine Tribe Fir, Larch, Cedar, &c 504 CLASS II. ENDOGENS. Order Hydrocharideae, or Frog-bit Tribe Water- soldier, Vallisneria . 508 Alismacea;, or Water Plantain Tribe Arrow-head, &c. . . 510 Vlll CONTENTS. I AGE Order Lemnacese, or Duckweed Tribe 513 Naiadese, or Pondweed Tribe Grass-wrack, &c. . . . 513 Orchidese, or Orchis Tribe Vanilla, Salep, &c 515 Scitaminese, or Ginger Tribe Turmeric, Cardamom, &c. . . 522 Marantaceae, or Arrow-root Tribe . . . . . . . 524 Musacese, or Plantain Tribe Banana 525 Iridaceae, or Iris Tribe Corn-flag, Crocus, Saffron . . . . 528 Amaryllideae, or Narcissus Tribe . . . . . .530 Liliacese, or Lily Tribe Hyacinth, Onion, Asphodel, Pine- Apple, &c 531 Palmacese, or Palm Tribe Date, Cocoa-nut, &c. . . . 543 Pandaneae, or Screwpine Tribe 550 Typhacese, or Bullrush Tribe 551 Aracese, or Arum Tribe Wake-robin, Eddoe, &c 552 Cyperacese, or Sedge Tribe Club-rush, Papyrus, &c. . . . 555 Gramineae, or Grass Tribe Corn, Rice, Sugar-cane, Bamboo, &c. . 557 Analytical Table . . 564 INTRODUCTION. OF all departments of Science, there is perhaps no single one capable of exercising such an advantageous influence on the mind of its cultivator, as Natural History. Every kind of knowledge has in it something that is valuable ; for, even if it be of no direct utility in the ordinary concerns of the world, the acquirement of it is a useful exercise to the mental faculties, and the possession of it may operate in a most beneficial manner on the habitual feelings, and give a corresponding direction to the whole course of life. It is desirable to cherish correct views of the benefits of different kinds of knowledge, that those may choose most advantageously for themselves whom the necessary business of life debars from the extended pursuit of it ; and without undervaluing other branches of Science, it may be safely affirmed that Natural History is capable of affording more to interest and instruct, more to refresh and relax the well-disposed mind, on a very slight acquaintance with it, than any other pursuit. Not a step can the learner ad- vance in it, but he meets with wonders previously unsuspected; not a height does he gain, from which his prospect is clearer and more extensive, but his notion of these wonders acquires a yet more astonishing vastness. The more he knows, the more he desires to know ; and the further he advances, the more does he perceive how much delight is yet in store for him. The beneficent Creator of all has not only ordained, that every part of His works should be good should be adapted to answer its designed end, and should contribute in the highest degree of 2 INTRODUCTION. which it is capable to the well-being of His creatures ; but He has made every thing " beautiful in its season," He has so formed the mind of Man that it derives pleasure from the con- templation of the glorious works around him. And it is, there- fore, a worthy employment of our faculties to encourage this pleasure ; and to place it upon a more solid and extended foun- dation, than that afforded by the mere forms and colours of the objects around us, however beautiful these may be. One great source of the pleasure derived from the inquiry into the structure and mode of existence of the living beings around us, arises from the beautiful adaptation of their parts to each other, and of the whole to the place it has to occupy, which we can easily trace in every one. The Philosopher who studies the motions of the heavenly bodies, and the station of this earth among them, traces these adaptations no less clearly ; but it re- quires profound and long-continued study to be able to compre- hend them aright. The Naturalist, ho wever, can discern them with far less research, in every plant that grows, in every animal that breathes ; and he meets with a constant variety, which prevents him from growing weary of the pursuit. Yet the young are too frequently kept in ignorance of the wonders and beauties around them ; and, whilst encouraged to learn many languages, and read many books, they remain unacquainted with the bright volume of Creation, the pages of which are daily and hourly unrolled before them, " written," to use the impressive words of Lord Bacon, " in the only language which hath gone forth to the ends of the world, unaffected by the confusion of Babel." But these pages are not to be read without some study : the alphabet and grammar must be learned, in order that their beauties may be rightly comprehended ; and those who are entering upon the inquiry need to be rightly directed by those who are more advanced. Natural History has been too generally shunned, as a Science of hard names and intricate classification, by those whose minds INTRODUCTION. 3 are occupied with the necessary employments and cares of the world, and who seek in the pursuit of knowledge a source of refreshment and re)axation. But the objects of its several de- partments are not commonly understood. The study includes the examination of the structure, habits, and mode of existence of all the living beings which so thickly people the surface of the globe ; and it is only in order to become acquainted with these more readily, that the Naturalist arranges or classifies them, placing those together which have most in common, and sepa- rating these from others which are widely different. Classifica- tion, therefore, is not the object of Natural History, but a means of gaining that object ; and it is very easy to enter upon many interesting inquiries, without the slightest knowledge of it. The structure and actions of Man, for example, may be examined in the greatest detail, without knowing anything of his place in the general scale of being (although such knowledge will often shorten the student's labour) ; and other kinds of animals and plants may be observed in the same manner. In fact, several of the most valuable and interesting observations we possess, upon the habits and actions of particular animals, were made by hose who de- voted themselves almost exclusively to that special object. Thus it is scarcely out of the power of any one to contribute something to the general stock of knowledge ; still less, then, can any be prevented from adopting some department of this pursuit, for the health and invigoration of their own minds. The study of the structure and actions of Plants, constituting what is known as VEGETABLE PHYSIOLOGY, has been less brought under the notice of those who pursue Natural History only for the improvement and recreation of their minds, than it perhpas deserves. In regard to the importance of the Vegetable King- dom in the economy of Nature, it can scarcely be said to rank lower than the Animal Creation; for all Animals are either directly or indirectly dependent upon Vegetables for their suste- nance, and must cease to exist if they were destroyed. The B'2 4 INTRODUCTION. beauty of the external forms of Plants is surpassed by that of their internal structure ; and the investigation of the latter is more easy than that of animals, besides being unattended with many drawbacks which must elsewhere be encountered. The objects of the Physiologist are never out of reach ; for barren indeed must be that country, which affords no shelter to the pro- ducts of the Vegetable Kingdom. The meanest and most com- mon herbs are, in his eyes, as interesting as the majestic tree or the rarest flower. The toilsome labours of the Collector, who seeks to bring together in his cabinet as large a number as pos- sible of the different tribes of plants existing on the surface of the globe, are not required by him ; nor is his mind fatigued by the difficulties and technicalities of classification. And what ren- ders the pursuit of this branch of Natural History peculiarly adapted to the female sex, is its freedom from the necessity of that corporeal suffering, which, however laudable its ultimate objects, the truly humane will always dread to inflict upon beings that have feelings like their own. The object of the following Treatise will be, therefore, to lead those who may be disposed to adopt our recommendation, to a pursuit which cannot fail to prove a source of interest and im- provement. It will be adapted as much as possible to such as have no previous information on the subject, beyond that which all young persons of ordinary capacity may gain by themselves ; and it will omit, therefore, several topics of high but less general interest, which those who feel inclined to examine them will find fully treated elsewhere. Wherever circumstances are compatible with Vegetable exist- ence, there we find plants arise. It is not only on the luxuriant soil, on which many generations have flourished and decayed, that we find the display of their beauties. The coral island, but recently elevated above the level of the sea, speedily becomes clothed with verdure. From the materials of the most sterile INTRODUCTION. 5 rock, and even from the yet recent cinders and lava of the volcano, Nature prepares the way for vegetable existence. The slightest crevice or inequality is sufficient to arrest the invisible germs that are always floating in the air ; and the humble plants which spring from these soon overspread the surface, deriving their chief nutriment from the atmosphere. Having completed their allotted period of existence, they die and decay ; but their death is only a preparation for the appearance of higher forms of vegetable structure. They are followed by successive tribes of plants, of gradually increasing size and strength ; until, in the course of years, the sterile rock is converted into a natural and luxuriant garden, of which the productions, rising from grasses to shrubs and trees, present all the varieties of the fertile meadow, the tangled thicket, and the widely-spreading forest. No extremes of heat or cold seem to put an entire check upon vegetation. Even in the desert plains of the torrid zone, the eye of the traveller is often refreshed by the appearance of a few hardy plants, which find sufficient materials for their growth in these arid regions. And wherever a spring of water moistens the soil and atmosphere around, a spot of luxuriant verdure is found. These Oases, as they are termed, are the stations at which caravans halt, when crossing the extensive wastes of parching sand ; and although their effect upon the mind is doubtless heightened by the dreariness of the preceding journey, there is no question that few spots can present greater richness of vegetation than these. It will be seen, hereafter, that heat, light, and moisture form the circumstances most favourable to the growth of plants ; and it is from the combination of the latter of these conditions with the former, that the vegetation of small islands in the tropical ocean is so peculiarly rich. These Oases are like such islands in the midst of a sea of sand ; and nothing can be a greater contrast with the desolation around, than " the green pastures" and " still waters" which they afford. Many remarkable facts might be mentioned, relative to the 6 INTRODUCTION. degree of heat which some forms of vegetation are capable of sustaining, and which, to some species, indeed, appears a natural and even necessary condition. A hot spring in the Manilla islands, which raises the thermometer to 187, has plants flou- rishing in it and on its borders. In hot springs near a river of Louisiana, of the temperature of from 122 to 145, have been seen growing not merely the lower and simpler plants, but shrubs and trees. In one of the Geysers of Iceland, which was hot enough to boil an egg in four minutes, a species of Chara has been found growing and reproducing itself ; and vegetation of an humble kind has been observed in the similar boiling springs of Arabia and the Cape of Good Hope. One of the most remarkable facts on record, in reference to the power of vegetation to proceed under a high temperature, is related by Sir G. Staunton, in his account of Lord Macartney's embassy to China. At the island of Amsterdam a spring was found, the mud of which, far hotter than boiling water, gave birth to a species of Liverwort (. 32). A large Squill bulb, which it was wished to dry and preserve, has been known to push up its stalk and leaves, when buried in sand kept up to a temperature much exceeding that of boiling water. Even the extreme of cold is not fatal to every form of vegetable life. In the realms of perpetual frost, the snow which covers mountains and valleys, and whose surface scarcely yields to the influence of the solar rays at midsummer, is in some places reddened for miles together by a minute vegetable, which grows in its substance, and has been supposed, from its very rapid in- crease, to have fallen from the sky. This will be hereafter described under the name of Red Snow (. 48), which is that commonly applied to it. The Lichen which forms the winter food of the Rein-Deer (. 39), grows entirely buried beneath the snow ; and its quantity may be judged of, by the number of the animals which find in it their sole support, during a consider- able part of the year. INTRODUCTION. Plants are found, too, in situations in which some peculiar noxious influence might be supposed entirely to prevent their growth ; as for example, in sulphureous springs. In fact, there are scarcely any circumstances, in which there is not some kind of plant adapted to exist. Thus, it is well known that soils, which have any considerable admixture of metallic ores, are not favourable to most kinds of vegetation ; and among such soils, those mixed with the refuse of lead-mines are the most sterile, so that this substance is often mixed with gravel, to prevent weeds from growing on garden-walks. Yet even on heaps of this material, thrown up around the openings of the mines, the Vernal Sand wort thrives, growing perhaps even more luxuriantly than in any other situation. The degree in which vitality is sometimes retained by Plants, under conditions apparently the most unfavourable, for a period to which it is difficult to assign a limit, is one of the most interesting and curious circumstances in their economy. In the greater part of those inhabiting temperate climates, an apparently complete cessation of activity takes place every year. The leaves wither and drop off; the stem and branches are reduced to a state of death-like bareness ; and all the changes in which life consists, appear to have entirely ceased. In some instances, the stems also die and decay, the roots only retaining their vitality; yet from these, with the return of the genial warmth and light of spring, a new stem shoots up, and new leaves and flowers are produced, in their turn to wither and decay. The torpor is not, however, so complete as it appears, in those durable and woody stems which defy the winter's blast ; for late experiments have shown that a slight movement of sap takes place even in a frosty atmosphere. In evergreen plants, on the other hand, this cessation of activity is less marked ; but the difference between their summer and winter condition is much greater than is ap- parent. In all these cases, however, the changes are periodical ; and are not altogether dependent on external conditions. For INTRODUCTION. nothing will prevent a plant from shedding its leaves nearly at its usual time ; and although by artificial heat, or by removal to a warmer climate, a new crop can be brought out within a short interval, this exhausts its powers, so that few kinds can survive the change of circumstances for any long period. Moreover, the period of inactivity cannot in these cases be prolonged beyond a certain fixed time ; for a plant, whose growth in spring is checked by the protracted influence of cold, loses its vitality altogether. But there are some instances in which this condition may be greatly prolonged. Bulbs, for example, of the onion, hyacinth, tulip, &c. have been kept for many years in this dormant state, capable of renewing the active processes of vegetation, of shooting up leaves and flower-stems into the air, and of trans- mitting their roots into the soil for many years; and there does not seem any particular limit to this power. Instances have been related of the growth of bulbs unrolled from among the bandages of Egyptian mummies ; but there is reason to believe that deception has been practised on this point upon the too- ready credulity of travellers, still there is nothing impossible in the asserted fact. Light, warmth, and moisture are the causes of the growth of these curious structures ; and when removed from the influence of these, there is no reason why a bulb should not remain unchanged for 100 years, if it can for 10; and for JOOO, if for 100. We shall hereafter see that the vitality of seeds under similar circumstances appears quite unlimited. (Chap, xii.) But there are some plants which, even whilst in a state of active vegetation, are capable of being reduced to a similar torpid condition, and of remaining in it for almost any length of time, without injury to life. There is a kind of Club-Moss inhabiting Peru, which is liable to be entirely dried up, when deprived of water for some time. It then folds in its leaves and contracts its roots, so as to form a ball, which, apparently quite devoid of animation, is driven about hither and thither by the wind ; as INTRODUCTION. soon, however, as it reaches a moist situation, it sends down its roots into the soil, and unfolds to the atmosphere its leaves, which, from a dingy brown, speedily change to the bright green of active vegetation. The Rose of Jericho is the subject of similar transformations; and the common Mosses exhibit the same in a less degree. These conditions are not the only ones admitting of great variation, and yet most important to the active operations of the vegetable structure. Light is as important as warmth and moisture to the processes of the economy; and yet we find plants adapted to thrive under the almost total deprivation of it. Sea- weeds possessing a bright green colour have been drawn up from the depth of more than 100 fathoms, to which the sun's rays do not penetrate in any appreciable proportion. Many of the Mushroom tribe have been found growing in caverns and mines, to which no rays from the sun, either direct or reflected, would seem to have access ; and even more perfect plants have been observed to vegetate, and to acquire a green colour (which is in general only produced under the influence of strong light), in such situations. On the other hand, we find some plants adapted only to exist, where they can be daily invigorated by the powerful rays of a tropical sun, with the complete daily change which results from their total absence, during a large part of the twenty- four hours; whilst there are others whose energies, after re- maining dormant during the tedious winter of the arctic regions, are aroused into a brief activity by the return of the luminary on whose cheering influence they depend, and whose rays are not withdrawn from them for weeks or even months together. Neither of these tribes could flourish, if transferred to the cir- cumstances of the other; and, opposite as these circumstances are, we observe that the Creator has adapted living beings to inhabit each, with equal suitableness. This adaptation of each species to particular circumstances, is often seen in an interesting manner on a small scale, on the ex- 10 INTRODUCTION. terior of large trunks of trees, old towers, &c. which are thickly clothed with Mosses and Lichens. Many of these avoid the light ; and their presence indicates the north side of the body to which they are attached. To others, again, the light in all its strength is genial ; and they frequent the southern aspect ; whilst other forms, intermediate in habits, frequent the eastern and western sides ; so that, on going round such a tower or large trunk, we observe a succession of different species which may be compared to that which is presented in the various latitudes, passing from the equator towards the pole. A similar succession, on a larger scale, is seen on ascending a high mountain between the tropics, such as the Peak of Teneriffe. The lower portion exhibits the vegetation of the surrounding country, in all the luxuriance and richness of an island in the torrid zone. Higher up, the traveller meets with productions similar to those found on the borders of temperate regions ; and to these succeed those of the medium temperate zone. Above these are perceived the alpine plants, which in northern Europe are found at a com- paratively trifling elevation ; and to these succeeds the dreariness of perpetual snow. These five distinct zones are well marked on the Peak of Teneriffe j each having a certain set of plants peculiar to it, as the plants of Northern and Southern Europe, and of Northern and Central Africa, are to those regions re- spectively. Thus we see that on no part of the earth's surface, under no peculiarities of soil or climate, is vegetation of some kind or other impossible. Every distinct tribe of Plants flourishes natu- rally under peculiar conditions, some preferring a warm atmo- sphere, others a cool one ; some only luxuriating in moisture, and others in the opposite condition of dryness ; some requiring the most intense light, and others only growing in darkness. There are some plants which are very deficient in the power of adapting themselves to slight changes in these conditions ; and these are accordingly restricted to certain localities favourable to INTRODUCTION. 11 their growth, and are hence considered rare plants. Thus, for example, there are certain species which require that the air sur- rounding them should contain a minute quantity of salt, dissolved in its moisture ; these only abound, therefore, near the sea- shore ; but they are seen to spring up in the neighbourhood of salt-works, or on lias soils which contain a good deal of saline matter, even many hundred miles inland, their seeds being con- veyed by the wind or by birds, which have spread them over the whole surface of the earth, but there only meeting with the conditions they require for their development. On the other hand, there are many which can grow in almost any situation, and which can adapt themselves to a great variety of circum- stances, often exhibiting evident changes of form and aspect, which are due to the influence of these. Such are common plants ; and many of them are among those most serviceable to man, on account of the improvement which can be effected in them by cultivation. , For example, the Potato, growing in its native climate the tropical portion of South America does not require for the growth of its young shoots that store of nourishment which, in temperate climates, is provided in its fleshy tubers ; and the edible portion is thus extremely small, since the warmth and moisture constantly supplied to it de- velop the growing parts without such assistance. But when transplanted to colder regions, and to a richer soil, that store is greatly increased in amount, and becomes one of the most im- portant of all articles of food to man. If it were not for this capability of adapting itself to new circumstances, the plant could not thrive in Northern Europe ; ' since its own powers of growth would be insufficient, when the external conditions are so much changed. But it is this very capability which renders it so useful to man. If the large Potatoes of European culti- vation be planted again in tropical climates, the produce is little superior to that of the original stock ; since, when circumstances no longer demand it, the acquired habit ceases. The Cabbage, 12 INTRODUCTION. Broccoli, Cauliflower, &c., are, in like manner, only varieties of one species, greatly altered by cultivation ; the plant which was the original stock of all, having been formed susceptible of more remarkable changes than most others, and thus rendered at the same time useful to man, and very easy of production. These instances, to which many more will be hereafter added, will suffice to show that it is not only in their original state, that the adaptation of each tribe of Plants to particular circumstances is exhibited ; since there are many which can thus spread them- selves, or may be spread by Man, over a large part of the globe. And in this capability, no less than in their original aspect, do we recognise the wisdom and power of the Almighty Designer, who willed that no portion of the globe should be unclothed by vegetation, and that from every part the herbage should spring forth for the supply of the Animal creation, which is entirely dependent on it, either directly or indirectly, for its sustenance. Such, then, being the universal diffusion of these beings, it is obvious that in no spot can he who seeks to make himself ac- quainted with then- structure and habits, be without some subjects for examination. And since the humblest and simplest Plants are found, when examined, to display an organisation as remark- ably and beautifully adapted to the functions they are to perform, and to the conditions in which they are to exist, as is that of the highest and most complicated, there is no reason why any should be neglected, however insignificant they may appear. The following Volume is intended to serve as a guide to those who are inclined to make the wonders of the Vegetable Kingdom an object of their regard, 'either as a source of recreation, or with those higher views to which the student of Natural History can scarcely avoid being led. For although no doubt can be enter- tained by the reflecting mind, that the Power, Wisdom, and Goodness of the Creator are everywhere operating with equal energy, whether in the simple but majestic arrangement of the heavenly bodies, or in those changes by which our own globe is INTRODUCTION. 1 3 rendered tit for the habitation of such innumerable multitudes of living beings, no one can help feeling that it is in the structure and actions of these beings themselves, that these attributes are more evidently manifested to the intelligent observer. And although the Animal kingdom has usually been regarded as affording more remarkable instances of their display than the Vegetable world, it may be doubted whether, when the latter is more closely examined, it will not appear equally or yet more wonderful ; the simplicity of the means being most strikingly contrasted with the vastness of the ends attained. CHAPTER I. OF THE GENERAL CHARACTERS OP LIVING BEINGS, AND THE DISTINCTION BETWEEN ANIMALS AND VEGETABLES. 1 . WHEN we examine any common Vegetable, we find that it is composed of a number of parts, differing in their form and structure, such, for example, as the stem, roots, leaves, and flowers. Each of these we might again subdivide into others ; the leaves, for example, into the footstalk on which they are sup- ported, and the expanded portion or blade. The blade of the leaf may be again distinguished into the midrib with the branching veins proceeding from it (which form as it were its skeleton), and the soft fleshy portion which clothes these ; and we might further convince ourselves, by a little examination, of the presence of a kind of skin or cuticle, which envelops the whole. Now these several parts of the structure of a plant, which have their respective uses in maintaining its life, the roots, for example, being to suck up moisture from the soil through which they spread them- selves, and to fix the whole structure in the ground, the stem to convey this to the leaves, which it elevates into the air, and ex- poses to light and warmth, the leaves to convert or elaborate this crude fluid into nutritious sap, and the flowers to produce seed by which the being propagates its race, these several parts are termed the organs of which the plant is composed ; and the uses of these parts the changes they perform are called their functions. 2. Now it is in the presence of these different organs, that one of the chief distinctions exists, between those structures which possess or have ever possessed life, and dead inert matter. In the stone or the mass of metal, we perceive that every part is similar to 16 GENERAL CHARACTERS OF LIVING BEINGS. every other part ; it lias the same structure, the same properties. If it possesses the crystalline form, it may be reduced into an almost indefinite number of smaller crystals similar to itself; and as to its properties, the chemist cares not (except as a matteu of convenience) whether he examines a single grain or a mass of a ton weight. Nay, of many substances the properties are so peculiar, that they can be recognised with certainty in quan- tities so minute as to be scarcely visible ; thus, arsenic, when administered as a poison, has been detected after death in a quantity probably less than the hundredth of a grain ; and yet the experienced chemist has no hesitation in asserting that this minute crystalline metallic substance is arsenic, because he recog- nises in it the same form and the same properties, which a larger mass of that substance would exhibit. 3. Far different is it with regard to a Plant or Animal. These also may be divided and subdivided; but they then entirely lose their original character ; for the parts or organs no longer bear any resemblance to the whole or to each other, either in form, structure, or properties. Thus, then, we see that the bodies which are formed to exhibit those actions to which we give the general term of Life, are peculiarly distinguished from dead matter, by the presence in them of a number of parts or organs > distinct alike in their form, structure, and properties ; hence such are called organised bodies. On the other hand, dead inert matter may be divided, with any degree of minute- ness, into parts similar to each other in form, structure, and properties ; hence it is termed inorganic, or destitute of organs. 4. There is another peculiarity possessed by living beings, in regard to their actions or functions. Some of these actions are governed by the same laws as those which operate on inorganic matter ; the blood is propelled by the heart of an animal, for example, through its system of branching vessels, just upon the same principle that a forcing-pump drives water through the pipes which convey it over a large city. But the nature of the force is quite different. In the latter case it is merely mechani- cal. In the former it results from a property peculiar to organised structure, and especially manifested in that form of it GENERAL CHARACTERS OP LIVING BEINGS. 17 which is called muscle ; the property, namely, of contracting, when a stimulus or irritation is applied to it. This and many other properties, therefore, which are exhibited by organised stfuctures, and to which we see nothing analogous in inorganic matter, are termed vital; and it is by the operation of these properties, that the series of changes is produced, which consti- tutes the Life of any organised being, whether Plant or Animal. Thus the heart has the property of contractility, which, when exercised, causes its contraction ; the eye has the property of receiving the impressions of light, which, when exercised, causes sensation ; and so on. 5. It may be asked, whence do these peculiar properties arise ? Are living bodies composed of different elements from those which exist around us in the form of dead matter ? Or are the elements the same, in a different state of combination ? And can we attribute the peculiar properties of organised tissues to the peculiar state in which their particles exist ? 6. To this it may be replied, that there is no element entering into the composition of organised bodies, which is not also found in the world around ; and further, that their chief elements are very few in number, compared with those which we find else- where. But the state of combination in which they exist is altogether peculiar, and such as the chemist cannot imitate ; any more than the mechanic can imitate the arrangement of their particles. In fact, every organised structure with which we are acquainted, had its origin in another, which produced a germ capable of living and growing, and of constructing its peculiar fabric out of the materials it derives from the inorganic world ; and this again was produced by a former one; and so on. 7. We perceive, therefore, that as the living organised beings which we now witness around us, are all the descendants of others, whose succession we might trace backwards to their first parentage, their actions are as much the results of the general laws which the Creator of all impressed on the frame of His first-formed creatures, as are the movements of the planets round the sun, of the laws which He impressed on them, when He first set those glorious spheres in motion. These laws are 18 GENERAL CHARACTERS OF LIVING BEINGS. continually maintained by His superintending agency, without which all would be anarchy and confusion. 8. It would seem to be a part of the exercise of those laws, that living beings should take from the inorganic world the mate- rials of their structure, should convert these into parts of their own fabric, should endow these with properties similar to those which their previous structures possessed, and should even pro- duce from them the germs of new structures, capable of perform- ing the same changes. Thus, the germ contained in the seed builds up the beautiful form and wondrous structure of the perfect tree, with scarce any other materials than water and air ; and of these it not only constructs its own stem, leaves, roots, and flowers, but (what seems yet more extraordinary) it imparts to its seeds, which, when separated from it and dried up, seem as it were dead, the power of repeating for themselves the same opera- tions. When once we understand it, however, as a general law, that it is a property of organised structures to produce the same, there is little difficulty in comprehending how they impart to the elements they employ, properties so different from those which they previously possessed. For we find in every case, that a change of combination in these elements is attended with a change in their properties. Thus an acid (such as oil of vitriol) and an alkali (such as soda) have properties peculiar to themselves, and in many respects contrary to those of each other ; but when they are brought together, they unite into a new compound, which possesses a form and properties differing from those of either of its elements. Again, sulphur, nitre, and charcoal, when simply mixed together in certain proportions, form a product, gun- powder, which possesses properties very different from those of either of its elements. Thus, then, we see that there is nothing improbable in the supposition, which all analogy supports, that the properties peculiar to organised structures depend upon the peculiarity of their constitution ; and this peculiarity, which the chemist and the mechanic alike fail to imitate, results, as we have seen, from the general law, that organised structures can only take their origin from beings already possessed of life. 9. One more preliminary consideration must be adverted to, GENERAL CHARACTERS OP LIVING BKINCJS. 19 before we quit these general views. The properties of organised bodies require certain conditions for their operation. Thus, a seed, which possesses vital properties in a dormant or inactive condition, and which may retain these for hundreds or even thousands of years, if placed in favourable circumstances so to do, begins to germinate or grow, as soon as it is submitted to the proper degree of warmth, moisture, and air. These, then, are the conditions requisite for those changes which WQ call its Life ; for the dry inactive seed can scarcely be said to be alive ; though, on the other hand, it certainly is not dead, since it possesses those properties or capabilities which enable it to live when placed in favourable circumstances. Again, suppose a Plant to be actively vegetating under the influence of light, warmth, and moisture, und to be suddenly deprived of all these$ by being carried, for example, into a cold dark cellar ; all its vital pro cesses receive a check, and it either dies, or, if sufficiently hard} to sustain the shock, it remains inactive until the necessary con ditions of its growth be renewed. These conditions are techni- cally called the stimuli to vital actions ; and thus we see that Life is the result of the operation of these stimuli upon organised structures possessed of peculiar properties. In attempting, therefore, to understand the history of Vegetation, we have three things to consider ; in the first place, the nature of the structure of plants; next, the properties which their several kinds of struc- ture respectively possess ; and lastly, the operation of various external stimuli upon these properties, so as to produce vital actions. 10. In considering the history of Animal Life, exactly the same course will be gone through ; but there will then be an additional subject to be treated of ; namely the internal stimuli, arising from the will of the being, which cause those actions that are termed spontaneous, since they have no direct dependence upon external stimuli, but originate in the animal itself. In the history of Man, these actions evidently form a large part ; but in the lowest animals they are very obscure, and can often scarcely be distinguished from the actions of plants. But even in man we have no difficulty in recognising a great number of actions c 2 20 DISTINCTION BETWEEN PLANTS AND ANIMALS. analogous to those which constitute the whole life of plants. Thus the absorption of food, its conversion into a nutritious fluid, the circulation of this through the system, its purification by exposure to the air, and the formation from it of new structures or the reparation of the old, are all actions over which the mind and will have no direct control, which go on quite inde- pendently of it, and which may be regarded as perfectly ana- logous to the same functions in plants. Hence they receive the name of functions of vegetative or organic life ; whilst those of sensibility and power of spontaneous movement are termed func- tions of animal life, as being peculiar to that division of organised Nature. In fact it is by their presence or absence, that the Animal or Vegetable character of a being must really be deter- mined. For though the external peculiarities of the higher kinds of Plants and Animals are quite sufficient to distinguish them from each other, yet there are many forms of the latter so low and simple, and so destitute of all that is regarded as pecu- liar to the Animal, that they cannot be readily distinguished from Plants. 11. It is in these lowest forms of both kingdoms, that we recognise the nearest approach to inorganic matter. For we gradually lose, in descending the scale, nearly all appearance of distinct organs ; so that the simplest plants that, for example, which constitutes the Red Snow of Alpine and Arctic Regions (. 48) instead of having stems, roots, leaves, and flowers, present us with apparently but a single organ, namely, a globular cell or little bag containing fluid. Even here, how- ever, we shall subsequently find that there is a distinction of parts ; and that, whilst the external surface is destined to imbibe nutriment from the moisture and air around, the internal forms the germs by which this simple little being is multiplied to a prodigious extent. CHAPTER II. GENERAL VIEW OF THE VEGETABLE KINGDOM. 1 2. WHEN we examine, however cursorily, the nature of the Plants around us, we at once perceive that their growth and suc- cession are regulated by certain laws. Thus we observe that all have a period of life to which they are more or less closely limited. Many of our commonest cultivated vegetables, the Corn, the Beans, the Turnips of our fields, and many of the plants which enrich our gardens with their flowers, live but for a single summer ; springing up from seed, uprearing a lofty stem, putting forth expanded and luxuriant foliage, unfolding gay and numerous blossoms, and finally withering away and under- going complete decay, in the course of a few months. In others, on the contrary, the duration of life is so great that it seems to be unlimited ; but there is good reason to believe, that the forest trees, which lift their massive stems to the light of day through a succession of many hundred years, have an appointed limit to their lives as regular as that of man, varying, like his, in indi- vidual cases, according to the circumstances of each. Every plant, then, has a period allotted by the great Creator of all, for its springing from seed, the unfolding of its leaves, the expansion of its blossoms, and its subsequent death and decay ; but while death is the lot of each generation that " cometh up and is withered," the perpetuation of the race is accomplished by another law, which provides for the production by each indi- vidual, before its own dissolution, of the germs of new individuals, from which plants may arise, that go through their allotted period of life, and in their turn decay, after producing the germs of a succeeding generation. 22 PERMANENCE OF VEGETABLE FOR .11 8. 13. Now besides these evident laws, another may be detected by a little observation, that the beings produced from these germs are in every essential respect similar to their parents: and that thus, after many thousands of generations, every plant or tree of the present day, may be regarded with certainty as having had a representative, at the period of the creation of the vegeta- tion which now clothes our globe. 14. The exceptions which may seem to exist in regard to this law are so in appearance only. The seeds of any particular kind of Apple, for instance, will not produce the same kind with any certainty, but are as likely to give origin to trees that shall bear very different and far inferior fruit. The same be said of the cultivated Dahlia, which presents so many beautiful varieties of colour ; the seed of a white flower is not much more likely to produce white Dahlias, than one with yellow or purple flowers. But in these and many more such instances, the different kinds are first produced by the influence of cultivation only, and had all originally but one stock ; and it is this stock, common to all kinds, which the seed has a tendency to perpetuate, rather than any one of the varieties which have been obtained from it by the art of man ; and we never find any tendency to produce a plant of an entirely different kind. Thus, the sour Crab is the stock of all the rich and delicate varieties of the Apple ; and if the seeds of any of these be sown in a poor soil, the plant will bear fruit resembling that of the original; but still it will be an Apple, and never a Pear or a Quince, or any other of the kinds most nearly allied. In the same manner, the original stock of the Dahlia is a plant having a very ordinary yellow flower, with but one circle of coloured florets ; but by the influence of cultivation the number of these circles is much increased, and the colours are deepened and enriched, as well as almost infinitely varied. The seeds of any of these, however, when sown in a poor soil, will produce a plant resembling the original parent ; and thus it is seen that there is no real exception in such cases to the general law, that the form of the species or distinct kind is propagated without any important alteration through successive generations; so that we may regard all the tribes of plants, really distinct CHARACTERS OF SPECIliS AND VARIETIES. 23 from one another, as having existed in nearly the same form since their iirst creation. 15. The Naturalist, then, regards as distinct species those races of Plants, the differences between which are evident, and are such as are not likely to have resulted from cultivation or any other external cause, and do not exhibit any tendency to alteration in progress of years. Such, for example, are those between the Apple and Pear among Plants, or the Dog and the Fox among animals. Among all the varieties of the Apple, dif- ferent as they are from one another, there is none which exhibits any close resemblance to the Pear ; and of all the kinds of Pear, there is none which so far loses its distinguishing characters, as to show any great similarity to the Apple. And yet among the varieties of the latter, there are kinds which are more different from each other in size, shape, colour, flavour, &c., than some of these are from the Pear ; but while all these show a marked tendency to change under different circumstances of growth, the internal differences between the Apple and Pear never exhibit any such tendency, but remain constant through all the varieties of each. The same may be said of the Dog and the Fox ; for, though some varieties or breeds of the former seem to differ from each other more than they do from the Fox, yet these differ- ences are liable to disappear altogether when the animals return to a wild state, all merging in a form most nearly resembling that of the Shepherd's dog; whilst the differences between the Fox, and the breeds of Dog most nearly allied to it, are con- stantly manifested. 1 6. On the other hand, the Naturalist regards as, varieties of the same species, those Plants and Animals, in the various speci- mens of which, however dissimilar they may be, the points of difference exhibit such a tendency to variation, that the one kind passes, as it were, into the other. Thus, the Grayhound and the Bull-Dog would be regarded as springing from originally different stocks, if we did not meet with intermediate forms of the Dog, which blend the peculiar characters of both. And the Primrose, Cowslip, and Polyanthus have been regarded as dis- tinct species, so considerable are their differences in form and 24 USES OF CLASSIFICATION. structure ; but the botanist is now aware, that many forms exi^t, which are intermediate between these, and that all may be raised from one stock. The same is the case with many other kinds of Plants. 17. This explanation, will, it is hoped, make the meaning of the term species understood ; and it is very desirable that clear notions on the subject should be a-cquired by the student of Natural History at the very commencement of his attention to the pursuit. It is computed that from 70,000 to 80,000 distinct species of Plants have been collected by Botanists from the surface of the globe ; and probably at least as many more remain to be discovered. It is obvious that an acquaintance with the structure and characters of such a vast number of different races, will be rendered much easier by classifying or arranging them, placing those together, which have a greater or less amount of general resemblance ; and separating others, according to their amount of difference. It is only in this manner, indeed, that any one, within the compass of a single life, can become master of the whole. In making such an arrangement, those species are first assembled into a group, termed a yenus, which resemble each other in all the more important particulars, and differ only in minor details. For example, the different kinds of Roses among plants, and the Lion, Tiger, Leopard, and other species of the Cat kind among animals, are considered as belonging to the same genus, their points of agreement being far more numerous than those of difference. Several genera may, in like manner, be united into a family; the various members of which have a common resemblance, though with many subordinate differences. By continuing to pursue the same plan, we form divisions of greater and greater extent ; until we are at last brought, by uniting subordinate ones, to the primary divisions, into which the whole kingdom may be at once distributed ; each of which divisions contains a large number of very dissimilar groups, united together by some common points of general resemblance. 1 8. Perhaps an illustration may make this subject better un- derstood. If we were to examine the people of any nation, in which there had been but little intermixture among its different GENERAL DIVISION OF VEGETABLES. 25 tribes (as was formerly the case in Scotland in regard to the clans), we might find a group of persons resembling each other so strongly in countenance, manners, form of speech, &c., and differing so much from all around them, that we should have little doubt of their belonging to one family; and, going further, we might meet with several such groups, each containing several individuals, and each differing in other characters from the rest. But if we were to bring these families together, we should pro- bably be able to trace more general and less marked resemblances among certain of these, which would lead us to associate them in clans, each of them including many families distinguished by certain points of similarity to one another, as, for example, a strongly-marked feature or a peculiar dialect, whilst differing in these same points from those of the remaining clans, and also differing from each other hi minor points. Again, among these clans we might find some resembling each other, and differing from the rest, in their complexion or language ; and thus forming tribes into which the whole nation might be subdivided. And, lastly, this nation would have certain points of conformity with those inhabiting the same quarter of the globe, whilst yet differing still more strongly from them, than its own tribes do amongst each other : and those inhabiting different quarters shall still more widely differ from each other, in general conformation, com- plexion, language, habits, &c. ; whilst still exhibiting those characters which are peculiar to Man, and which separate him from all other animals. 19. The primary division of the Vegetable Kingdom is into PHANEROGAMIA or Flowering-plants, and CBYPTOGAMIA or Flowerless-plants. Though these designations are not strictly correct, they serve to indicate sufficiently well the character of the tribes, to which they respectively apply. To the former division belong nearly all cultivated vegetables, the whole of the forest-trees both of our own and of other countries, and a very large proportion of the vegetation, that naturally covers the surface of the earth, in temperate and warm climates. Many of the tribes contained in it, however, produce no distinct blossom ; but these possess the essential parts of the flower (as will be 26 PIIANEllOGAMIA AND CRYPTOGAM I A. hereafter explained), and form that perfect seed, which is cha- racteristic of this division. In all the PHANEROGAM i A, (save in a few exceptions which stand, as it were, on the border of the division, and connect it with that of Cryptogamia, of which they exhibit some of the characters,) we find a certain number of distinct parts, such as the stem, roots, leaves, and flowers ; and the germs by which they propagate their race, come to an advanced state before quitting the parent, and are furnished with a store of nourishment, by which they are afterwards assisted in their growth. The seed of these plants has, therefore, a complex structure ; and the young plant shoots from it in a certain determinate manner (Chap. xn.). 20. In the CRYPTOGAMIA, on the other hand, the parts con- cerned in the reproductive process are much less evident, and the germs which they form, are much less matured when they quit the parent structure. In the Mosses, Ferns, Sea- Weeds, &c. no seeds are produced : but a number of small particles are liberated, which are termed spores ; and each of these contains within it several minute germs, which spring from it without any par- ticular regularity, and which are not assisted in their growth by any such store of nutriment, as that provided in the seed. The absence of this is a very important character; for it seems a universal law of Nature, that the higher the grade a living being is ultimately to attain, the longer is the period during which it is assisted, either directly or indirectly, by its parent, during the early stages of its growth. Thus Quadrupeds, which bring forth their young alive, and maintain them afterwards by suckling, are higher than Birds, which produce them, in the first instance, in a state far less mature. And Man, who in his adult age rises far above all other animals, is longer dependent upon his parent during the period of infancy. 21. The embryo of the Flowering-plant, contained in the mature seed, is so far advanced at the time of quitting its parent, that it possesses one or two distinct leafy bodies, termed cotyledons, which, when the seed begins to germinate (as it is called), a-.e pushed up to the surface of the ground, and there turn to a green colour, and perform all the functions of true leaves, until these CRYPTOGAM1A. FERNS. 27 make their appearance. Now of all trace of cotyledons, the embryo of the Flowerless-plant is entirely destitute ; and the whole group is hence spoken of as Acotyledonous. On the other hand, of the Flowering-plants, some possess one, and others two cotyledons ; and this difference in the structure of the seed is accompanied by so many other differences in the structure of the stems, the leaves, flowers, &c., that it serves to mark the two principal subdivisions of this portion of the Vegetable Kingdom. ACOTYLKDONE.E. MONOCOTYLEDON KJE. DICOTYLKDONK.*:. CONFERVA. Cocos. tiiNApis. FIG. ]. That in which one cotyledon exists is termed Monocotyledonous ; and that in which there are two, Dicotyledonous. The common Bean or Pea will serve as a characteristic illustration of the latter ; and the Wheat and other Grass-seeds, of the former. 22. The general aspect of the Flowering-plants is sufficiently well known, to render a more minute account of them here unnecessary ; since the object of this preliminary view of the Vegetable Kingdom, is to render the student, who may have been previously entirely ignorant of the subject, prepared to enter with advantage on that detailed description of the mode, in which the several tribes grow and reproduce themselves, which it is the object of the Physiological portion of this Volume to communicate. A fuller sketch of the principal divisions of the Cryptogamia will, however, now be given, as few ordinary observers bestow much attention on them. 23. Of all the CRYPTOGAMIA, the Ferns approach most nearly to Flowering Plants. The general aspect of those inhabiting this 28 GENERAL CHARACTERS OF FERNS. and other temperate countries, is well known. They present a small number of leaves, generally much divided into leaflets, and these again often minutely subdivided, each arising from the ground by a woody stalk, which is commonly regarded as the stem of the plant. The true stem, however, is buried beneath the ground, or sometimes creeps along its surface ; and the branches it sends upwards into the air, are really the leaf-stalks. (Fig. 2). In many Ferns of tropical climates, the true stem rises upright, like that of a tree, and bears at the top a beautiful crown of those peculiarly graceful leaves, for which th~ Ferns are remarkable. The height of these Tree Ferns, which are most luxuriant in the small islands, where they are furnished Fro. 2. POLYPOUIUM VUL- OARE, COMMON POLYPODY, OR WALL FERN. FIG. 3. TREE FKRV. with a more regular supply of atmospheric mo'sture than they can obtain at a greater distance from the sea, is sometimes as GENERAL CHARACTERS OP FERNS. 29 much as 40 or 45 feet ; so that we must not judge of the whole race, by the comparatively insignificant specimens, which our own climate produces. These stems do not, however, afford any wood sufficiently solid to be employed in the arts. (Fig. 3.) 24. The organs of reproduction in Ferns, have no evident analogy with the flowering system in higher plants. Nothing like a flower is ever seen in this group ; and the fructification is incorporated, as it were, with the leaves, being generally found, when mature, in brown spots or lines on their under surface or at their edges (Fig. 2) ; the nature of the organs composing these will be hereafter described (Chap. xu.). In most Ferns, all the leaves are concerned in producing the fructification ; but in some (of which the Osmunda regalis, or Flowering-Fern, as it is commonly but incorrectly termed, is an example) certain leaves are devoted to the production of the fructification, and are termed fertile : whilst others only perform the usual functions of leaves, and are called sterile leaves, from the absence of repro- ductive power in them. The term frond is generally applied to the leafy portions of the Cryptogamia, as distinguishing them from the true leaves of Flowering Plants, which have only one set of offices to perform. Sometimes the fertile frond of Ferns altogether loses its leafy aspect, its edges being completely rolled in, so as to inclose the fructification ; and this separation of the reproductive from the nutritive portion of the system, which makes the distinction in Flowering-plants between the flowers and the leaves, is as complete as any which the Cryptogamia exhibit. 25. One of the most interesting peculiarities of the Ferns, is the spiral mode in which its leaflets and leaves are rolled up, before their first appearance ; each leaflet being rolled up towards the rib which supports it, the ribs again towards the midrib, and the midrib towards the footstalk. The unfolding leaves, in a state closely resembling those represented at the top of Fig. 3, may constantly be seen during spring, in spots where this group abounds ; and, when examined, display the most provident and beautiful arrangement of the numerous minute parts, of which the whole leaf consists. Few common objects, indeed, are more 30 GENERAL CHARACTERS OP FERNS 'AND MOSSES. interesting than this, which requires neither skill, nor the assist- ance of instruments, for the detection of its beauties. 26. Although Ferns constitute but a comparatively small part of the present vegetation of this country, they must have been much more abundant in a former period of the eartlTs history, especially at the time when the beds of coal were being formed ; since their remains now constitute by far the largest part of those, which are preserved to us with tolerable perfection in a fossil state. This is partly due, however, to the remarkable power which these plants possess, of resisting the action of water ; by which other plants and trees were decomposed, their remains having contributed to form those immense masses of Coal, which are so important to Man, not only for his personal comfort, but for the arts of life. The Ferns are able to withstand the effects of even a very prolonged immersion in water, with scarcely any change ; whilst not only the soft tissue of plants, but the heart- wood of most trees, decays so completely under the same circum- stances, as to leave little or no traces of their character. In tro- pical islands, the Ferns constitute a most important part of the whole vegetation ; being equal in number, in the Sandwich Islands, to one-fourth, and in Jamaica to one-ninth, of all the Flowering-plants existing in each of these localities. 27. The next principal group of Cryptogamia,that of Mosses, is as interesting from the delicacy and minuteness of all the plants composing it, as other tribes of the Vegetable Kingdom are for the majesty of their forms, or the vast extension of their foliage. These are so generally and easily recognised as such, that a minute description of them is at present unnecessary ; but it should be stated that the term Moss is commonly applied, not only to the true Mosses, but also to many Lichens. The true Mosses, how- ever, are always to be known, by the green colour they possess, except when dried up ; while the Lichens are usually grayish in their aspect. Mosses usually possess a sort of stem, round which the minute leaves are arranged with great beauty and regu- larity ; but neither this stem, nor the leaf-stalks of the leaves, have any truly woody structure ; and they more, closely resemble the simple tissue of the lowest plants, than the complex fabric MOSSES. MUNGO PARK. 31 CASiRE.N'SIS, OR FKATHi-R- JVIoss. of those already noticed, to which they seem to bear a greater resemblance in external form. Mosses do not, like Ferns, bear their fructification upon the leaves or modifications of them ; it is inclosed in a little case or urn, which is furnished with a lid, and is borne on a long distinct stalk, so as to be very easily ob- served when full-grown. The interior of this minute organ usually contains a structure of great beauty, which will be hereafter de- FIG. 4.-iiYp.vuM scribed in detail ; but it is interesting to know, that it was by the contemplation of this, that the heart of Mungo Park, the African traveller, was revived, when the difficulties by which he was surrounded had almost extinguished hope within him. The passage has been often quoted ; but, it may be hoped, never without its use ; and it does not seem superfluous to introduce it here. 28. This enterprising traveller, during one of his journeys into the interior of Africa, was cruelly stripped and robbed of all that he possessed, by banditti. " In this forlorn and almost helpless condition," he says, " when the robbers had left me, I sat for some time looking around me with amazement and terror. Which- ever way I turned, nothing appeared but danger and difficulty. I found myself in the midst of a vast wilderness, in the depth of the rainy season, naked and alone, surrounded by savage ani- mals, and by men still more savage. I was five hundred miles from any European settlement. All these circumstances crowded at once upon my recollection, and I confess that my spirits began to fail me. 1 considered my fate as certain, and that I had no alternative but to lie down and perish. The influence of religion, however, aided and supported me. I reflected that no human prudence or foresight could possibly have averted my present suf- 32 GENERAL CHARACTERS OF MOSSES. ferings. I was indeed a stranger in a strange land, yet I was still under the protecting eye of that Providence, who has condescended to call himself the stranger's friend. At this moment, painful as my reflections were, the extraordinary beauty of a small Moss irresistibly caught my eye ; and though the whole plant was not larger than the top of one of my fingers, I could not contemplate the delicate conformation of its roots, leaves, and fruit, without admiration. Can that Being (thought I) who planted, watered, and brought to perfection, in this obscure part of the world, a thing which appears of so small importance, look with unconcern upon the situation and sufferings of creatures formed after his own image ? Surely not. Reflections like these would not allow me to despair. I started up ; and disregarding both hunger and fatigue, travelled forwards, assured that relief was at hand, and I was not disappointed." 29. Mosses are found in all parts of the world, in which the atmosphere is moist; but they are far more abundant in temper- ate climates, than in any between the tropics. They are among the first vegetables that clothe the soil with verdure, in newly- formed countries; and they are the last that disappear, when the atmosphere ceases to be capable of nourishing vegetation. The first green crust upon the cinders, with which the surface of Ascension Island was covered, consisted of minute Mosses. This tribe forms more than a fourth of the whole vegetation of Mel- ville Island, one of the most northerly spots in which any plants have been observed; and the black and lifeless soil of New South Shetland, one of the islands nearest to the South Pole, is covered with specks of Mosses struggling for existence. 30. Besides their power of resisting extremes of temperature, Mosses exhibit a remarkable tenacity of life, when their growth is checked by the absence of moisture ; so that they may often be restored to active life, even when they have been dried for many years. Hence they offer abundant sources of interest to the observer of Nature, at a season when vegetation of other kinds is almost entirely checked. For it is most curious to ob- serve, how gay these little Mosses are on every wall-top, during the winter months, and in the early spring, almost, or perhaps MOSSES. LIVERWORTS. 33 the oniy things, which seem to enjoy the clouds and storms of the season. They choose the most exposed situations, spread out their leaves, and push up their delicate urns, amidst rain, frost, and snow ; and yet there is nothing in their simple and tender structure, from which we could infer their capability of resisting influences so generally destructive to vegetation. But it is with Plants as with Animals. The more simple and lowly the being, the greater is usually its tenacity of life, under cir- cumstances which depress the vital powers of higher kinds; whilst the influences which they require are often too powerful for it. Thus, Mosses and Lichens, over-stimulated by heat and dryness, wither away in summer; but vegetate freely at a season when there is no other vegetation, and when their humble fabrics cannot be overshadowed by a ranker growth. 31. Mosses were fancifully termed by Linnasus, servi, serv- ants, or workmen ; for they seem to labour to produce vegeta- tion in newly-formed countries, where soil can scarcely yet be said to be. This is not their only use, however. They fill up and consolidate bogs, and form rich vegetable mould for the growth of larger plants, which they also protect from cold during the winter. They likewise clothe the sides of lofty hills and mountain-ranges ; and powerfully attract and condense the watery vapours floating in the atmosphere, and thus become the living fountains of many streams. They are sometimes so c6m- pletely dried up by drought, that they escape notice ; and then, when moistened by rain, they appear to have suddenly clothed a barren heath, or overspread a dry wall with verdure, on which, however, they really existed before. 32. Closely con- nected with the Mosses is the tribe of Hepaticce, or Liverworts, the lower forms of which are near- ly connected with the Lichens. Some of them differ but little in their general characters from F '- &-HWATIC*. OR LIVEKWOHTS. 34 LIVERWORTS. MARCH ANTIA. Mosses, being distinguished by certain peculiarities of fructifi- cation. Others, however, have no distinct stem or separate leaves; but extend horizontally into a flat leaf-like expansion; the fructification is sometimes elevated above this on a little stalk; but in the tribes most nearly allied to the Lichens, it is imbedded in it, as it is in that group. Their general habits closely resemble those of the Mosses. Their leafy expansions are soft and green ; differing much, therefore, from the dry scaly crusts of the Lichens. They are capable of reviving, like the Mosses, after being dried up; and, from the rapidity of their growth, and a peculiarity in their mode of propagation, they are often seen to spread over a damp surface with great rapidity. One of the most common species is the Marchantia poly- morpha, which will be often referred to in this treatise, on account of the many interesting facts which the attentive study of it has disclosed. It is usually found growing on moist surfaces, and often where there is little or no soil ; it is very com- mon in the chinks between paving-stones F.G. 6.-M A R,HANTTA POLY- in unfrequented places, and on the surface eof the commonest of the earth contained in garden-pots, as of the Liverworts. 6 also upon walls which from any cause are kept constantly damp. 33. Besides the regular fructification, this little plant has a very curious apparatus, for the production of small leafy bodies, which may be regarded as buds, and which spontaneously sepa- rate from the parent structure and develop themselves into new beings. As these, when mature, are liable to be washed out of their receptacle by rain, and to be carried to different parts of the neighbouring surface, and as they grow very rapidly whilst supplied with moisture, the rapid extension of the plant under such circumstances is easily accounted for. The little receptacles of a basket-form, in which these are produced, may be generally seen in some stage of their growth, on the upper side of the leafy expansion of which the plant consists ; and they constitute GENERAL CHARACTERS OF LICHENS. 35 beautiful objects for a low magnifying power of the microscope. The budlike bodies, having the form of flat disks, like coins, may often be seen to grow, whilst still contained in their re- ceptacle, and even to graft themselves, as it were, on the parent plant. 34. The group of Cryptogamic plants termed Lichens, mostly consists of dry, hard, scaly crusts, destitute of leaves and stems, and even of anything bearing a resemblance to them ; they grow upon bare walls, the trunks of old trees, and other such situa- tions, in which they are much exposed +o light, and not abundantly supplied with moisture. In their general structure they nearly approach to the Sea- weeds ; and differ from them chiefly, in being adapted to live in air, instead of in water. The dry hard crust is usually of a greyish colour ; its upper surface, being ex- posed to the light and warmth of the sun, performs the functions . 7. SCALY LICHEN. of leaves; whilst from beneath it there proceed a number of minute hair-like filament 4 *, which serve both to fix it by clinging to the substance on which it grows, and also, it may be believed, for the absorption of fluid the chief uses of the roots in the Flowering Plants. Lichens are among the slowest in growth of all plants, and the least subject to alteration from decay. Whilst alive, they scarcely exhibit any change through a long series of years; and when dead, their forms and colours are scarcely altered by being dried. 35. There can be no doubt, that the greater part of this tribe derive their nourishment from the atmosphere and its contained moisture alone ; flourishing as they do upon sterile rocks, with- out a particle of soil or mould in their neighbourhood. There o2 MODE OP GROWTH OP LICHENS. are many species, which ordinarily grow upon the trunks of trees; and these are commonly spoken of as Mosses, but incorrectly so. The shaggy appearance of the apple-trees of an old Orchard FIG. 8. LICHENS. is in general entirely due to Lichens, although a few Mosses may sometimes be found among these. Of such Lichens, by far the greater part vegetate indifferently on all kinds of trees, and they flourish equally well upon a damp wall ; so that there is no reason to suppose that they derive any more nutriment from the stems on which they grow, than is afforded by the moisture covering their surface. There is no doubt, however, that some trees are much more favourable to their growth than others. Thus, the Beech, Elm, Sycamore, and Lime, are comparatively seldom found infested with the common Beard-moss, which clothes so profusely the Fir, Ash, Oak, or Birch ; so that the poet's epithet of u rude and moss-grown beech" is by no means appropriate. 36. The fructification of the Lichens is not much raised above the general surface, but is usually im' edded in certain parts of it, somewhat differently formed from the rest, and termed shields. The early growth of these plants is favoured by darkness ; but for the ripening of the reproductive bodies, a considerable quantity of light is required. The development of the shields, which takes place under its FIG. 9. PARMEMA PERFORATA Lichen with projecting shields. SOIL PRODUCED BY SUCCESSIVE TRIBES. 37 influence, is frequently accompanied by so great a change in the general appearance of the plant, that the same species growing in dark and moist places, in which the fructification was not evolved, has been considered to belong to a distinct kind from the perfect specimen. No true Lichens are ever found in mines, caverns, or other places deprived of light ; nor are there any that grow entirely under water ; although some species, which con- nect this group with the Sea-weeds, grow on the sea-shore, where they are alternately submerged and left dry by the tide. 37. To the Lichens may well be applied the title of Vernaculi, or bond-slaves, which Linnzeus fancifully gave to the Sea-weeds, regarding them as fettered to the rocks on which they grow. For the Lichens seem as it were chained to the soil, which they labour to improve for the benefit of others, although they derive no nourishment from it themselves. The mode in which they prepare the sterile rock, for the reception of plants that require a higher kind of nourishment, is most remarkable. They may be said to dig for themselves graves, for the reception of their remains, when death and decay would otherwise speedily dissi- pate them. For whilst living, these Lichens form a considerable quantity of oxalic acid, (which is a peculiar compound of car- bon and oxygen, two ingredients supplied by the atmosphere, Chap, vi.) ; and this acts chemically upon the rock, (especially if of limestone,) forming a hollow which retains the particles of the structure, when their term of connected existence has expired. The moisture which is caught in these hollows, finds its way into the cracks and crevices of the rocks ; and, when frozen, rends them into minute fragments by its expansion, and thus adds more and more to the forming soil. Successive generations of these bond-slaves continuously and indefatigably perform their duties ; until at length, as the result of their accumulated toil, the barren and insulated rocks, or the pumice or lava of the volcano, become converted into fruitful fields. For when Flora's standard has once been planted on tracts thus claimed, they are soon colonised by plants of other tribes. The Mosses, Ferns, and other Cryptogamia follow them ; and at last, by the growth and rlecay of successive generations of plants, a sufficient thickness of 38 USES OF LICHENS. soil is produced, for the nourishment of the luxuriant herbage, and the support of the lofty forest-tree. And thus, by the labours of these apparently insignificant plants, Men are enabled to reap their harvest, and to supply themselves with timber from forests, and cattle increase and multiply, on what was formerly but a naked and desolate rock. 38. One of Nature's truest though least attractive delineators, has thus faithfully described such a process, as it occurs on ruined buildings. It should be remarked, however, that the terms seed, foliage, and flower, are not strictly correct as applied to the Lichens, which have none of these. " Seeds to our eyes invisible, will find On the rude rock the bed that fits their kind ; There in the rugged soil they safely dwell, Till showers and snows the subtle atoms swell, And spread th' enduring foliage ; then we trace The freckled flower upon the flinty base ; These all increase, till in unnoted years The stony tower as gray with age appears, With coats of vegetation thinly spread, Coat above coat, the living on the dead. These then dissolve to dust, and make a way For bolder foliage, nursed by their decay : The long-enduring ferns in time will all Die and depose their dust upon the wall : Where the wing'd seed may rest, till many a flower Shows Flora's triumph o'er the falling tower." CRABBE'S Borough. 39. Besides this important office in the economy of Nature, some of the Lichens are peculiarly useful to man, on account of the valuable dyes they afford him. The blue dye termed Archil, or Litmus, which is changed to a bright red by the action of acids, is obtained from several species of Lichen growing in the Canary Islands and elsewhere ; and many other species, not at present regarded, might probably be converted with advantage to the same use. To the Laplanders, the tribe of Lichens is of peculiar utility ; indeed on it they depend for their subsistence. For though it is not an article of their own diet, a humble Lichen, commonly known as the Reindeer Moss, supplies the animal, on which they depend for almost all their means of ex- ALGJ3, OR SEA-WEEDS. .39 istence, with food throughout their dreary winter; its vegetation not being checked by the snow beneath which it grows. A species of Lichen growing on the rocks of the Arctic regions of North America, has afforded subsistence for many days, to some of the adventurous explorers of that desolate country, when other pro- visions could not be obtained. 40. The group of Algae, or Sea-weeds, includes the very lowest forms of vegetable organization ; but it also comprehends some plants whose structure possesses great complexity. The Algae may be considered as Lichens formed to exist in water ; their general structure, and the arrangement of their parts, being: much alike. The hard scaly crust of the Lichens, formed under the influence of the sun and air, and never attaining any great extent, seems to bear a remarkable contrast with the immense leaf-like expansions, composed of soft, easily decomposed tissue, presented by the Algae ; yet wherever any of the former group inhabit damp shady places, their character much approaches to that of the latter ; and in regard to some plants, it is difficult to fix the group to which they belong. Although the term Sea- weed is that usually considered equivalent to Algee, it should be understood that the class includes many species, which are inhabitants of fresh water. Of this kind are the Confervas^ the long green hair-like filaments of which are almost con- stantly found attached to stones, at the sides or bottom of running streams. These are among the simplest forms of vegetation. Each fila- ment consists of a single row of minute cells or vesicles, attached to each other end to end. Every one of these vesicles is capable of growing by itself, and of reproducing its kind ; for at a certain period a minute orifice appears in its walls, from which issue forth some of the little green particles it contains ; and these become the germs of new plants of the same descrip- /f ^, v FlG. 10. CONKERV.K, tion (Chap. XII.). with separate filament 41 . The higher kinds of Alga inhabit Sea- ma & nified - 40 MODE OP GROWTH OF SEA- WEEDS. water only. They often assume the forms of more perfect plants, presenting an appearance as of roots, stems, and leaves. But these parts have not those differences of structure which are characteristic of them when truly formed, and which will be hereafter described ; on the contrary, they all consist of the same LAMINARIA BACCHARINA. FIG. 11. Fucus VESICUIXJSUS. kind of simple and similar texture as that of the Confervse ; the expanded leaf of a Sea- weed being composed, as it were, of a number of filaments of the Confervas, laid side by side. The structure of these apparently different parts being thus so nearly the same, their functions or uses have an equal conformity ; f < r the root-like fibres at the bottom of the stem, only serve to fix the plant to the rocks or stones, to which it is its habit to attach itself, instead of absorbing or sucking up nourishment as in the Flowering-plants. The cause of this difference is obvious. Where the whole plant is constantly immersed in the fluid, which affords it the materials of its growth, no one part of it need be \ specially endowed with the power : and it will be hereafter MODE OF GROWTH OF SEA- WEEDS. 41 shown (Chap, iv.) how strong the contrast is, between the func tions of the true roots of Flowering-plants, and the root-like organs of the Algse. 42. The higher Algae sometimes attain a prodigious extent of development, forming vast submarine forests of the most luxuriant vegetation. Thus the Chorda filum, a species common in the North Sea, is frequently found of the length of 30 or 40 feet ; and in the neighbourhood of the Orkneys, it forms meadows, through which a boat forces its way with difficulty. It grows in the form of a long and even cord (whence its name), about the size of a quill, attached at one end to the bottom or shore, and the rest supported by the water. This is nothing, however, to the prodigious extent of the Macrocystis pyrifera, which is reported to be from 500 to 1500 feet in length, the long and narrow fronds having an air-vesicle at the base of each, the stem not being thicker than the finger, and its upper branches as slender as common pack-thread. Another tropical species attains the length of 25 or 30 feet, with a trunk as thick as a man's thigh. Sometimes these stems are solid, and sometimes hollow ; the tubular stem of one species of Laminaria, found near the Cape of Good Hope, has been used by the natives as a trumpet, when dried. An- other species furnishes the natives of some parts of Australia, with a large proportion of their instruments, vessels, and even of their food. 43. The marine Algaa differ much in their habits. Some species grow altogether beneath the water, attaching themselves below the lowest tide-level. Others fix themselves where their fronds may float on the surface, and may be exposed in some degree to the direct influence of the air. Others again frequent a height, at which they are left dry at every retreating tide ; and some are found in situations, in which they are scarcely ever covered by water, thus approaching in habits, and in character also, to the Lichens. Although most attach themselves to rocks or other solid masses, frequenting the shores or shallows rather than the open sea, there are some exceptions, among which one of the most remarkable is the Sargasso or Gulf Weed, which floats on the surface of the ocean, in the Gulf of Mexico, and in the current which sets from this towards the north. Immense 42 HABITS OF SEA-WEEDS. fields of it are seen by the navigator, extending as far as the eye can reach, and conveying the idea of rocks and shallows. dangers far distant. It is sometimes so abundant, as seriously to interfere with the progress of the ship through the water ; and it was this which alarmed the crew of Columbus, in his first voyage of discovery. 44. The distribution of different species through the ocean, is influenced by latitude, by the depth of water, and by currents, nearly in the same manner as the higher plants are affected by temperature, elevation above the sea level, and the conditions of the atmosphere as to dryness and calmness. Some species can thrive well under considerable variation in these conditions ; whilst others are dependent upon certain states of them for their existence. The former, therefore, are extensively diffused, being found along many shores, whilst the latter are rarer, and only inhabit particular spots, in which these conditions are met with. Contrary to what might have been expected, considering that the Algae do not imbibe any nourishment by the spreading root- like fibres, which attach them to the solid masses of the shore, it has been ascertained that they do not grow indifferently on all kinds of rocks ; but that if, for example, along the same line of coast, there be an alternation of limestone and granite rocks, some species will attach themselves in preference to the former, and others to the latter. This curious fact can only be explained by the supposition, that small quantities of the mineral matter are dissolved by the water of the neighbourhood ; and that in this manner they act upon the plant. 45. Of all tribes of plants, the Algas are commonly reputed the least useful ; in fact their inutility was proverbial among the ancients. Yet neither in regard to the general economy of nature, nor as to the wants of man, are they to be so considered. They supply food to a large number of marine animals, which browse upon them as those inhabiting the land do upon its most luxuriant pastures. Cattle have been very profitably fed on some species abundant on the northern shores ; and even become so fond of this diet as greedily to seek for it. Many kinds, such as the Alaria esculenta, called in Scotland badder-locks or honev-ware, furnish a wholesome and palatable food for Man, USES OF SEA-WEEDS. 4*3 and are employed by the poorer classes along the shores of the north of Europe ; whilst others are reckoned a luxury by the rich. The Laver of this country, the Carrageen, or Irish Bog Moss (as it is erroneously called), and other edible substances, belong to this group ; and from other species of it, are formed the edible birds'-nests, which are considered so great a delicacy by the Chinese, the best being sold for nearly their weight in gold. These nests are constructed by a bird resembling the Swallow, ! ui. 12. ALAIUA KSCULKNTA. , . , , .. ~ , . which reduces the Sea-weed in its stomach to a sort of gelatinous mass, before employing it for this purpose. 46. But all these uses are comparatively trifling, when the other modes in which the Algse may be made beneficial to Man are considered. The kelp, from which until recently the glass-maker and soap-boiler derived most of the alkali which they required for their manufacture, is nothing but the ashes of Sea- weeds ; which contain a large proportion of this substance, derived from the water in which they grow. Those most employed for this purpose, have been the Fucus vesiculosus and other species of Fuci, the Chorda Jllmn, and several species of Laminaria. Other means of obtaining soda from sea- water have now partly superseded * " FIG. 13. Fucus VKSICULOSUS. this; but until recently, it was almost the only method. The account handed down by tradi- tion, of the mode in which glass was invented, whether it be itself true or false, serves to illustrate the properties of the Sea- weed. It is said that some sailors cast ashore by shipwreck, hav- 44 PECULIAR TRIBES OF ALGJE. RED SNOW. ing kindled a fire on the sand, supplied it with some dry sea- weed as fuel ; and that under the ashes, a mass of vitrified matter was afterwards found, resulting from the union at a high temperature, of the soda of the sea- weed, with the silex of the sand. Many Algae also constitute a very valuable manure; and might be much more used than they are. But one of their greatest bene- fits to Man, consists in the Iodine with which they supply him ; a substance which is of the most important use to the Phy- sician, in the treatment of many diseases, and which is a nearly certain cure for some, which were formerly considered almost irremediable. One species, moreover, which abounds on flie shores of China, furnishes a glue and varnish to the Chinese, even superior to that which is obtained from animal matter in this country. It seems, when once dried, to resist the action of water ; for it is employed to fill up the lozenge-shaped inter- stices in the network of Bamboo, of which windows are fre- quently constructed ; as well as to strengthen and varnish the paper of their lanterns. A species abounding on the southern and western coasts of Ireland furnishes a good size for house- painters ; and there are many others, which contain an amount of gelatinous matter, that might be rendered useful in various ways. 47. Besides the tribes of whose character a sketch has been thus given, there are others of a doubtful nature, which are generally referred to this group ; although some peculiar charac- ters which they exhibit, and their similarity to certain animal forms, render it doubtful whether they ought not to rank with that kingdom. They are mostly formed of cells jointed together, as the Confervas ; but some of them seem to possess a different interior structure ; and others exhibit very curious motions, which can scarcely be distinguished with certainty from those of animals. In one of these groups, a large quantity of flinty matter is con- tained in the walls of the cells ; so that they perfectly retain their form, after all the vegetable structure has been destroyed, by the action of heat and acids. The cavity of the cells, too, is some- times seen to be partly occupied by large angular crystals. All the plants (if such they be) of this group are very minute. 48. There is, however, a group yet simpler than these, of the vegetable nature of which there is no doubt- On the damp parts RED SNOW, FUNGI. 45 of some hard surfaces, is not unfrequently seen a greenish or red- dish slime, which, when examined with the microscope, is found to consist of a number of minute cells, having little connexion with each other, but imbedded in a sort of jelly, which surrounds and connects them. On some minute variations between these simple plants, various distinctions have been formed ; one is known under the name of gory dew, from its red colour ; and another, which appears on the surface of snow, tinging extensive tracts with a deep crimson, is known as red snow. This some- times appears so suddenly, and over so large a space, as to lead to the belief that it had fallen from the sky ; but its growth and multiplication are so rapid as to leave no difficulty in accounting for its appearance.* This plant, which may be regarded as one of the simplest forms of vegetation, if not the very simplest, con- sists of a little bag or membrane, forming what is called a cell. A large number of these are commonly found together; but each one is separate from the rest, and is to be regarded as a distinct individual. It obtains its own nou- FIG. u. PROTOCCOCIS rishment, by absorbing the fluid around ; and JJgJJJ 8 ' r magnified^ grows and comes to maturity, without any showing its separate J ' * cells or vesicles partly other support or assistance, than that afforded imbedded in a slimy by the air and moisture, with which its sur- jelly ' face is in contact. When come to maturity, a number of minute granules may be seen within it ; these are the germs of new plants ; and, when liberated by the rupture of the parent-cell, they go through precisely the same series of changes. This little plant will be often referred to, in illustration of the sim- plest conditions, in which the processes of the Vegetable eco- nomy can be performed. In its habits, flourishing as it does only in very damp situations, though partly exposed to the air, it must be regarded as belonging to the Algae ; but it bears a close correspondence with the lowest forms of a group that now remains to be considered ; whose conditions of existence, how- ever, are very different. * The Author is aware that recent discoveries have shown, that the Red Snow of some districts consists of Animalcules ; but he is satisfied, from hia own obser- vations, of the real existence of the Plant here described. 46 PROPAGATION OP FUNGI, 49. In their general simplicity of structure, the Fungi (the tribe including Mushrooms, Puff-balls, and many kinds of blight, mildew, and mould), correspond with the Algae and Lichens ; Fiu. 15 VARIOUS FORMS OF THE HIGHER FUNGI. but they differ remarkably in habits, and in the character of their fabrics. Fungi will not grow with the simple nourishment which serves for their support ; but require to be fed with decay- ing animal or vegetable matter of some kind ; and they chiefly frequent situations, in which decomposition is going on with rapidity, and which are at the same time dark and warm. It is very remarkable to observe the constancy with which particular species make their appearance on particular substances. Thus, no fungus but the common edible Mushroom ever grows upon the mushroom- spawn (as it is called) ; though this does not neces- sarily contain its germs, being merely a kind of manure com- posed of various decaying substances, which prepares the soil to receive them from the atmosphere. Again, there is a species of mould which is only found on the surface of the dung of cats deposited in moist and obscure places. Almost every tribe of plants has its peculiar species of blight or rust, to the attacks of MILDEW, &C. 47 which it is liable, and which differ from the kinds infesting nearly similar vegetables. 50. The universality of the appearance of the simpler kinds of Fungi, such as mould, mildew, &c. upon all spots favourable to their development, has given rise to the belief that they were spontaneously produced by the decomposing substances. But there is no occasion for this mode of accounting for it ; since the extraordinary means adopted by Nature, for the production and diffusion of their germs, suffices to explain it. The duration of the lives of individuals among the Fungi is very brief; their tis- sue is soft and succulent, sometimes containing so little solid matter, as almost to melt away when broken down ; and never possessing any considerable amount of firmness. Now in the Algae, where we have seen the development of the individual taking place to such an enormous extent, the fructification is generally obscure, and sometimes even scarcely perceptible. But in the Fungi, all the energies of the plant seem directed to the production of the germs of new ones ; its own size seldom attains any great extent ; but the number of these germs is often almost incalculable. Thus, the fine dust which issues from the common Puff-ball when mature, consists entirely of these little bodies, which are diffused through the air, and seem to float about in it, ready to develop themselves when they meet with the fitting conditions. In a single Fungus, above ten millions have been counted ; and these were probably by no means the whole num- ber contained in it. When these minute germs are once spread through the air, there are so many means provided for their dif- fusion, that it is difficult to conceive of a place from which they should be excluded. 51. However improbable, then, it may at first sight appear, that every portion of the air we breathe should contain the germs of a large number of species of Fungi, ready to develop them- selves whenever the peculiar conditions adapted to each kind are presented, there seems good reason to believe, that such is the case ; and in this manner we may account for several facts, of some practical importance, relative to the production of those very troublesome forma of vegetation, known by the names of mould, mildew, &c. It is well known that fruit-preserves are very 48 DEVELOPMENT OF MOULD, MILDEW, &C. liable to be attacked by the common bead-mould: which no care employed in completely closing the mouths of the jars can prevent. It has been remarked, however, that they are much less liable to suffer in this way, if not left open for a night before they are tied down ; and it is therefore probable, that the germs of the mould sow themselves, as it were, in this luxuriant soil, before the jar is covered. Again, there is a particular kind of cheese, much valued by some epi- cures, which derives its peculiar flavour from the quantity of fungous vegetation it contains. It is prepared simply by breaking up the curd, and ex- magnified: its posing it for a day or two, in small lumps laid stems consist- , , , . . , ing of single upon a cloth, to the sun and air ; it there seems Jointed 10 toge^ to rece i ye tne g erm s of Fungi, which afterwards ther. vegetate in it, and spread their growth through the mass whilst it is yet soft. 52. In all these instances, the Fungi derive their nutriment from organic matter, which is either already in a state of decay, or will readily decompose. There can be little doubt, that their development hastens decay when it is slow, or even causes decomposition in substances which previously exhibited none. Thus, a fruit-preserve, into which no mould finds its way, may remain sweet for many years ; but the growth of the mould produces chemical changes in it, which are of a kind to supply the plant with the materials it requires. There is another very remarkable group of Fungi, which develops itself in the midst of the tissues of living plants and animals. To it belong, amongst others, the mildew, rust, smut, &c. of corn and other vegetables ; these are distinct plants, having all the characters of true Fungi, but growing from the ears, stems, &c. of those they infest, so as to appear like a part of themselves. In fact the question has been raised, whether they are really produced from separate germs, or whether they are not diseased parts of the structure on which they appear. But there seems little doubt, that distinct germs are introduced from without. They can be communicated from one plant to another ; and they may perhaps enter through the stomata or breathing - pores hereafter to be described FUNGOUS VEGETATION IN PLANTS AND ANIMALS. 49 . 91 ) ; though experiment shows it to be more likely, that they are conveyed in the water which drains through the soil, and FIG. 17. JECIDIVM CANCELLATUM ; , a leaf upon which it is seen growing of the natural size ; b, peridia, magnified. that they are introduced into the system with the fluid which is absorbed. In that case they must be almost immeasurably small ; since it is known, that the minutest particles of any sub- stance which can be artificially obtained, are usually rejected by the roots, as too large, when diffused through water which is being absorbed through their pores. 53. Animals are liable, as well as plants, to the growth of Fungi within their bodies. There is a species of Wasp in the West Indies, of which individuals are often seen flying about with plants of their own length, projecting from some part of their surface ; the germs of these having been originally intro- duced, probably through the breathing pores at their sides, (ANIM. PHYSIOL. . 320), and taking root, as it were, in their substance, so as to develope a luxuriant vegetation. In time, however, the fungous growth spreads through the body, and destroys the life of the insect ; and it then seems to grow more rapidly, the decomposing tissue of the dead body being still more adapted than the living structure, to afford it nutriment. 50 MUSCARDINE OF SILK-WORMS. 54. A very curious example of the growth of Fungi within the living animal body has lately been detected ; and the know- ledge of it has proved of great importance. The Silk-worm breeders of Italy and the South of France, especially in particular districts, have been subject to a considerable loss, by a disease termed Muscardine, which sometimes attacks the worms in large numbers, just when about to enter the chrysalis state. This disease has been ascertained to be due to the growth of a minute vegetable of the Fungus tribe, nearly resembling the common mould, within their bodies. It is capable of being communicated to any individual from one already affected, by the introduction beneath the skin of the former, of some particles from the diseased portion of the latter; and it then spreads in the fatty mass beneath the skin, occasioning the destruction of this tissue, which is very important as a reservoir of nourishment to the animal, when about to pass into a state of complete inactivity. The plant spreads by the extension of its own structure; and also by the production of minute germs, which are taken up by the circulating blood, and carried to distant parts of the body. The disease invariably occasions the death of the Silk- worm ; but it does not show itself externally until afterwards, when it rapidly shoots forth from beneath the skin. The Caterpillar, Chrysalis, and Moth are all susceptible of having the disease communicated to them, by the kind of inoculation just described; but it is only the first which usually receives it spontaneously. The importance of this disease to the breeders of silk- worms, led, as soon as its true nature was understood, to careful inquiry into the circumstances which favour the production of the fungus ; and it has been shown that, if the bodies of the caterpillars, which (from various causes) have died during breeding, be thrown together in heaps, and exposed to the influence of a warm and moist atmosphere for a few days (as has been very commonly the case), this fungus almost invariably appears upon them, just as other kinds of mould appear on other decaying substances ; and that it is then propagated to the living worms, by the diffusion of its germs through the atmosphere. The knowledge of this fact, and the precautions taken in consequence, have greatly diminished the mortality. VEGETATION OP YEAST. 51 55. Another very curious example of vegetation of a fungous character, in a situation where its existence was not until recently suspected, is presented in the process of fermentation. It ap- pears from microscopic examination of a mass of yeast, that it consists of a number of minute disconnected vesicles, which closely resemble those of the Red Snow, and appear to consti- tute one of the simplest possible forms of vegetation. These, like seeds, may remain for almost any length of time in an inactive condition, without losing their vitality ; and their power of growing, when placed in proper circumstances, is not destroyed by their being entirely dried up, nor by their being exposed to such extremes of temperature, as the boiling point of water and seventy-six degrees below zero. When these bodies are placed in a fluid, in which any kind of sugary matter is contained, they commence vegetating actively, provided the temperature be sufficiently high ; and the decomposition which they effect in the fluid, the nature of which will be presently explained, is that which constitutes its fermentation. 56. If a small portion of a fluid in this state be examined at intervals, with a powerful microscope, it is observed that each of the little vesicles contained in it puts forth one or more pro- longations or buds, which in time become new vesicles like their parents ; these again perform the same process ; so that, within a <%t - **<&- c^ ^cP FIG. 18. DIFFERENT STAGES OF THE VEGETATION OF YEAST ; a, single cells of which it at first consists ; 6, cells with buds ; c, the same more advanced ; d, rows of cells corresponding to those of Fig. 9. few hours, the single vesicles have developed themselves into rows of four, five, or six. This is not the only way, however, in which they multiply ; for sometimes the vesicles are observed to burst, and to emit a number of minute granules, which are the germs of new plants, and which soon develop themselves into E2 52 VEGETATION OF YEAST. additional cells. By the time that five or six vesicles are found in each group, the fermentation is sufficiently far advanced for the purposes of the brewer ; and he then takes measures to check it, by which the vegetation of the yeast is suspended. The groups of vesicles then separate into individuals, resembling those which first constituted the yeast ; and thus a greatly-increased amount of this substance is the result of the process. 57. The process of fermentation consists, as regards the fluid, in the conversion of the solution of sugar, into alcohol or spirit of wine ; and this is effected by the action of the vegetating fungus, which withdraws from the fluid, for the supply of its own growth, that portion of its elements which constitutes the dif- ference between sugar and alcohol. A process very similar to this takes place when the common Mould, growing upon the surface of a sweet preserve, causes its fermentation. The little plant bears considerable resemblance to the Red Snow ; but differs from it in the two following important particulars. The Red Snow can flourish, when supplied with air and moisture alone, the conditions which have been mentioned as favourable to the growth of the Algse ; whilst this Yeast-plant can only grow in the solution of vegetable matter, which is ready to undergo decomposition, and which yields it a kind of nutriment that the Red Snow does not require, but which is necessary for the growth of all the Fungi. This is an instance, then, of what was formerly stated, respecting the close resemblance between the lowest forms of these simple tribes, which differ from one another more in the conditions necessary for their respective growth, than in their own structure. The other point of difference con- sists in the extension of the Yeast-plant by buds, that is, by the formation of new cells as continuations from the old ones, as well as by the formation of separate germs ; whilst the Red Snow is propagated by the latter only. It is interesting to trace, in a being so extremely low in the scale, the two kinds of Reproduc- tion, which are performed in a manner so much more complex, and apparently so different, in the higher plants. 58. The growth and reproduction of the more complex kinds of Fungi, differs in no essential particulars, from the correspond- HIGHER FORMS OF FUNGI. ing processes in the lowest and simplest. In the Bead-mould (Fig. 16), every cell of which the little stems are composed, lives for itself alone ; and, like that of the Yeast-Plant, it may either develop new cells from its extremities, by a process re- sembling budding, or it may burst and set free a multitude of contained germs, each of which may become a new cell. This process very much resembles that which takes place in the Con- fervas (. 40). But in the higher Fungi, as in the higher Algae, we find a certain set of cells set apart for reproduction, and con- tained in a distinct portion of the plant. This is the case, for example, in the common Puff-ball, in which the reproductive cells or spores are enveloped by a distinct membrane, which sets them free, in the form of fine dust or smoke, by bursting when they are mature. Nearly the same conformation exists in the JEcidium (Fig. 17), and in other plants resembling it ; in these, the membranous envelope, which encloses the spores, and dis- charges them by an orifice in its side or summit, is termed the peridium. A still higher form is seen in the Agaric or Mushroom tribe ; of which a specimen is repre- sented in Fig. 19. Here we have a stem, 0, with rootlets at the base, by which the plant imbibes its nutriment ; at its up- per extremity, it bears the pileus or cap, b ; and on the under side of this are seen the gills, c, which radiate from the centre towards the circumfer- ence. These are composed of a membrane in which the reproductive cells are imbedded. At an early period of its development, the pileus is folded down upon the stem, and is inclosed in a membrane termed the voha or wrapper, the remains FIG. 19. AMANITA MUSCARIA. a, the hollow stripes or stem ; 6, the pileus or cap; c, the lamella or gills; d, the volva or wrapper ; e, the velum or veil. 54 FUNGI. DRY ROT. of which, after it has burst, are seen at d. Agarics in the various stages of their development, are represented in the upper part of Fig. 15. 59. Of all the Cryptogamia, the Fungi are the most import- ant to Man ; and their influence seems at first sight exerted rather to his injury, than to his benefit. Those minute species which constitute mildew, blight, rust, &c., often destroy, to an immense amount, the fruits of the earth, upon which he relies for his chief support. An instance has been just recorded, in which the lives of animals that administer to his luxury, are also destroyed in large numbers. The decay of timber in the mode commonly termed dry-rot, is caused by the growth of Fungi ; of which several species are frequently concerned in effecting this most injurious process. The ravages which they commit in ships, and in every kind of wooden structure, as soon as a settlement is made, can only be conceived by those who have witnessed and examined them. The devastations they have committed in our navy and merchant vessels, excited attention to the subject ; and led to the invention of the process, now known by the name of Kyanising* (from the name of its inventor) ; but their destruc- tion of house timbers is quite as rapid and complete, though less common. " I knew a house," says Mr. Burnett, "into which the rot gained admittance, and which, during the four years we rented it, had the parlours twice wainscotted, and a new flight of stairs ; the dry-rot having rendered it unsafe to go from the ground-floor to the bed-rooms. Every precaution was taken to remove the decaying timbers when the new work was done ; yet the dry-rot so rapidly gained strength, that the house was ulti- mately pulled down. Some of my books which suffered least, and which I still retain, bear mournful impressions of its ruth- less hand ; others were so much affected, that the leaves resem- bled tinder, and, when the volumes were opened, fell out in dust or fragments." The decay of the wood seems partly due to the * This process consists in soaking the wood or other material in water, in which corrosive sublimate has been dissolved ; and in this manner, a change is effected, which seems to deprive the germs of Fungi of the power of obtaining nutriment. The substance termed Krcosote has been lately employed for the same purpose, with very successful results. USES OF FUNGI. 55 growth of the Fungi in its suhstance, which is decomposed by it, as are the fluid and half-solid matters already spoken of ; and partly to the moisture, which they are the means of introducing into its interior. The germs of these plants fall into the chinks of the timber, where they take root ; and in their growth, they greatly widen these chinks, and thus give admission to moisture from without, as well as to a new set of these minute germ 8, which may prove even more destructive ; and by a continuance and repetition of these processes, the whole strength of the timber is at last destroyed. 60. The power of expansion which these plants possess, soft as their tissues seem, is truly wonderful. Some years ago the town of Basingstoke was paved; and not many months after- wards, the pavement was observed to exhibit an unevenness, which could not be easily accounted for. In a short time after the mystery was explained; for some of the heaviest stones were completely lifted out of their beds by the growth of large toad- stools beneath them. One of these stones measured twenty-two inches by twenty-one, and weighed 83 Ibs. ; and the resistance offered by the mortar which held it in its place would probably be even a greater obstacle than the weight. It became necessary to re-pave the whole town, in consequence of this remarkable disturbance. 61. But although in these and many other ways, Fungi are injurious to Man, the benefits they confer upon him far outweigh their occasional devastations; and it is only through the constancy of the former that they are overlooked and unappreciated. It is not only to Man that they are of the most essential service, but to the whole Animal kingdom. To Fungi may be justly applied the designation, which has been conferred upon Insects, that of the "scavengers of nature;" for, like insects, they labour with the most astonishing effect, in the removal of refuse and decaying substances, which, were they left upon the surface of the earth, would prove not merely useless tenants, but injurious incuni- brances. Their vapour-like germs float about in the atmosphere, in countless myriads, only waiting for the presence of a fitter soil, on which to alight and grow. As long as there is no refuse decomposing matter to be removed, these spores remain inactive 56 IMPORTANT USES OP FUNGI. and undeveloped, ("the scavengers are unemployed"); but as soon as any quantity, large or small, of decaying animal or vege- table matter, is left exposed, it is soon covered with a depo- sition of spores, which rapidly develop themselves into Fungi of various kinds. 62. Their astonishing fertility, and the rapidity with which they arrive at maturity, are among the most remarkable characters of this tribe of plants. Of the former, some account has already been given. Of the latter many instances are recorded. Thus one species has been known to attain the weight of 341bs, in six weeks ; and on the continent, Fungi of the same tribe have grown to upwards of lOOlbs., having begun from a point not perceptible to the naked eye. A large fungus of the Puff-ball tribe has been seen to grow in one night, from a minute speck, to the size of a large gourd. No other living beings have powers of growth at all to be compared to this. The more rapid the decomposition, and the greater the quantity of noxious exhalations which would thus be spread through the atmosphere, the greater is the tendency to multiplication and luxuriant growth, in these humble plants, to which such exhalations serve as the most appropriate food. 63. Hence what has been said by Naturalists of Insects, applies with equal truth and force to these humbler tribes ; and we may adopt, with slight modification, an interesting state- ment, which has been given of the agency of Insects, as a striking delineation of the operations of the Fungi. 64. " The peculiarity of their agency consists in their power of suddenly multiplying their numbers, to a degree which could only be accomplished in a considerable lapse of time, by any larger beings ; and then as instantaneously relapsing, without the intervention of any violent disturbing cause, to their former insig- nificance. If, for the sake of employing on different but rare occasions, a power of many hundreds or thousands of horses, we were under the necessity of feeding all these animals at a great cost in the intervals, when their services were not required, we should greatly admire the invention of a machine, such as the steam-engine, which should be capable at any moment of exert- ing the same degree of strength, without any consumption of food during the periods of inaction ; and the same kind of admi- USES OF FUNGI. 57 ration is strongly excited, when we contemplate the powers of Insect and Fungous life, in the creation of which Nature has been so prodigal. A scanty number of minute individuals, only to be detected by careful research, and often not detectable at all, are ready, .in a few days or weeks, to give birth to myriads, which may repress or remove the nuisances referred to. But no sooner has the commission been executed, than the gigantic power becomes dormant ; each of the mighty host soon reaches the term of its transient existence ; and when the fitting food lessens in quantity, when the offal to be removed diminishes, then fewer of the spores find soil on which to germinate ; and when the whole has been consumed, the legions before so active all return to their latent unnoticed state, ready, however, at a moment's warning again to be developed, and, when labour is to be done again, again to commence their work, either in the same districts, or to migrate in clouds like locusts to other lands. In almost every season there are some species, but especially in autumn there are many, which in this manner put forth their strength ; and then, like the spirits of the poet, which thronged the spacious hall, 'reduce to smallest forms their shapes im- mense.' " 65. Among the uses of Fungi to Man, their service as food must not be forgotten. In chemical composition they closely resemble animal flesh ; and, accordingly, those of them which are free from injurious properties, furnish a highly nutritious article of diet ; and some of the rarer species are greatly valued as dainties by the epicure. There is much difficulty, however, in distinguishing the innocent from the noxious species of Mush- room ; and many fatal accidents have occurred from the employ- ment of the poisonous kinds. Amongst the Fungi remarkable for their peculiar properties, may be mentioned one which is of great service, from its astringent properties, as a styptic, to check the flow of blood ; and another which has the power even when dry, of producing a curious kind of intoxication, and which is used for that purpose by the Tartars. This is the species repre- sented in Fig. 19. It is occasionally found in great abundance in this country ; and is distinguished by the bright red hue of its upper surface, which is studded with white spots. CHAPTER III. OF THE ELEMENTARY STRUCTURE OF PLANTS 66. When we examine yet more closely, into the conforma- tion of the different parts, of which an organised structure is composed, we find that, though the several organs are variously constructed, and are adapted for different offices or functions, they are built up, as it were, of the same materials. With the same bricks, stones, mortar, and timbers, a church, a palace, or a prison may be reared. Just so is it in organised structures. We do not find that each organ is entirely different from the rest, though it has usually something peculiar to it ; but we are enabled to separate it into many distinct portions, something similar to which, if not exactly correspondent, may be recognised in other parts, Thus, for example, it was formerly stated, that the leaf consists of a midrib and veins proceeding from it, a fleshy substance filling up the interstices, and a cuticle or skin covering the whole. Now the midrib and veins, as well as the footstalk of which these are a prolongation, consist of three kinds of struc- ture ; woody fibre, to which they owe their toughness, and by which they are adapted to give support to the softer structures ; ducts or canals, for the transmission of fluid ; and spiral vessels, which are designed to convey air. On tracing these to fhe stem, it will be found that they all exist in it under the same form, and that these portions of the leaves are in reality but con- tinuations of it. Again, if we examine the fleshy substance which lies amongst them, we shall find that it corresponds very closely in character with the pulp of soft fruits, or the pith of the stem. And if we strip off the cuticle and investigate its struc- ture, we shall perceive that it is but another form of the same kind of substance, and that it corresponds with the skin which PRIMARY TISSUES OF PLANTS. 59 covers all the newly-formed parts of the stem and branches, as well as the various parts of the flower, and even the roots. 67. These several kinds of structure are termed the primary tissues, being the elements, as it were, of which the edifice is built up ; and they are to the vegetable fabric what the bones, muscles, fat, blood-vessels, nerves, skin, &c. are to the animal. 68. Even these primary tissues may be regarded as consist- ing of other parts still more simple, namely, membrane and fibre. The fleshy portion of the leaf, for example, or the pulp of fruits, consists of a number of little bags adhering together : each bag or vesicle consisting of a delicate membrane, without any perceptible orifice, and containing fluid. The membrane which incloses an egg after the shell is removed, will afford a good illustration, on a large scale, of the nature of these vesicles; they may, however, be readily distinguished and separated in an over-ripe orange, where they are of considerable size. The mem- brane which composes their walls may be regarded as one of the very simplest forms of vegetable tissue. Again, if the stalk of a strawberry or geranium leaf be carefully cut round but not through, and the two parts be then pulled asunder for a short space, a number of glistening fibres, of extreme delicacy, will be seen running from one portion to the other. If these be put under the microscope, it will be evident that they had lain in spiral coils, which are partially straightened when they are thus drawn out, just as when a spiral spring is strained. These were coiled within the membranous tubes, that constitute the external sheath of the spiral vessels, which have been mentioned as existing in the leaf- stalk ; and thus we are able to separate these vessels into the two other elements, membrane FIG. 20. SPIRAL and film. These very minute delicate spiral FIBREsm * AWN OUT - fibres must not be confounded with the woody fibre, of which mention has been made, and the nature of which will be pre- sently explained. 69. The delicate Membrane, of which, in combination with 60 ELEMENTARY MEMBRANE AND FIBRE. fibre, all the tissues of plants may be regarded as consisting, when they are newly formed, is of variable thickness and trans- parency In general, however, it is quite sufficiently trans- parent, to allow the colour of fluids in contact with it to be dis- tinguished on the other side ; and accordingly, though itself colourless or nearly so, it often appears tinged, in consequence of the cells or vessels which it forms, being filled with coloured fluid. Thus the cells of leaves appear green, those of the parts of flowers yellow, blue, red, &c. ; not because that colour exists in the membrane of which they are composed (which, if they could be emptied, would appear almost colourless), but on account of the minute colouring particles diffused through their contained fluids. One of the most remarkable properties of vegetable membrane, is its power of allowing fluids to pass slowly through it, even though no visible pores or apertures can be detected in it. Occasionally the appearance of such apertures exists, when membrane is highly magnified ; but this appear- ance is sometimes produced by grains of semi-transparent matter sticking to it ; and is sometimes due to that portion of the mem- brane being thinner than the rest, through the deposition of new matter upon certain points, subsequent to the first formation, of which several examples will be presently given.' 70. Elementary Fibre may be compared to hair of extreme delicacy ; its diameter often not exceeding the 1-12,000 of an inch. It is generally transparent and colourless, and is usually disposed in a spiral direction. Its peculiar property is elasticity, combined with a degree of firmness, which, for its diameter, is very considerable. Accordingly we find its chief use to be, the keeping open, like an interior spring, the delicate membranous tubes through which air is to pass, and the preventing these from being pressed together by the growth of neighbouring parts. Not unfrequently, however, it seems less elastic than usual, and is broken during the processes of growth, into several smaller fragments ; which then exhibit a peculiar tendency to grow together, in various irregular forms. In this way, several pecu - liar kinds of tissue are produced, which will shortly be noticed. 7J. The one most universally present, no kind of plant being CELLULAR TISSUE. Ol without it in some form or other, and many being entirely com- posed of it, is that called cellular tissue, from its being made up of a number of separate cells, or minute bags, adherent together. These, when first formed, are usually nearly globular, or of a figure resembling an egg; so that, if cut across, their walls would exhibit a series of cir- cles touching each other rninf (V\cr points {I Ig. FIG. 21. VARIOUS FORMS OF CELLULAR TISSUE ; a, geparate yesicles Qf ^ egg . shape d form ; b, section of Afterwards, cubical cellular tissue of pith; c, section of muriform cellular tissue. OOOoor at 21, ). , , , however, they are gra- dually pressed against each other, and their sides become flat- tened. Their form will then depend upon the amount of the pressure on the respective sides. If it have been equal in all directions, the cell will sometimes be cubical, as it is often found in pith (Fig. 21, &) ; or it will have the form termed the dode- cahedron, which is a solid having twelve equal sides (Fig. 22). But if it be pressed more on one side than another, it will be narrowed in that direction, and elongated in the other. Thus the original form of the cell may become greatly modified, during the growth of the plant. In gene- ral, the greatest elongation take,s place in the direction of most rapid increase ; FIG. 22. SECTION OF IRREGU- , , . . , , , - . . , LARLY COMPRESSED CELLULAR but this is not always the case ; for in the TISSUE ; the honey-comb ap- gtems of most trees in this climate, there pearance of the greater part . 7 is due to the 12-sided form of is a peculiar set of cells extending from SSXZSSZSSi tte .P ith towards th f b^.^ich have tion, present hexagons or their greatest length in a horizontal direc- tion ; and the cells being of an oblong flattened form, and arranged like bricks in a wall, this kind of structure has been called muriform (wall-like) cellular tissue (Fig. 21, c). 72. From what has been said of the permeability, or power of giving passage to fluids, which vegetable membrane possesses, 62 PROPERTIES OP CELLULAR TISSUE. it may be inferred that this power is also possessed, by the simple modification of it just described. Accordingly we find this to be the case, fluids being conducted through cellular tissue very readily from one part to another : but still it affords a sufficient degree of resistance, to cause the transmission of fluids most readily in the direction of the greatest length of the cells, where, of course, there will be the fewest partitions in a given space. Thus, therefore, fluids absorbed at the bottom of a stem, will pass upwards through its cellular tissue more readily than in any other direction, except in the case of the muriform cellular tissue, which conducts fluids horizontally with the greatest readi- ness. The object of these peculiar adaptations will be more fully described in Chap, vi., where the structure and offices of the different parts of the stem will be severally detailed. 73. In the fabric of the lowest tribes of Plants, such as Sea- weeds, Lichens, the Fungi (or Mushroom tribe), Liverworts, and Mosses, little besides cellular tissue and its simple modifications can be found ; and it forms a large proportion of the structure of even the highest tribes. Thus in every Plant, the leaves, flowers, bark, pith, and fruit, consist almost entirely of cellular tissue ; and it is even found in the woody part of the stem and roots, besides forming the largest proportion of those soft succu- lent stems, which are only of short duration, dying as soon as the fruit they bear has ripened. The whole of the young plant, too, even of the highest tribes, consists, like the permanent forms of the lower, of this kind of structure. It is only when the true leaves have been unfolded, and are actively performing their functions, that the other kinds of tissue show themselves. In all newly-forming parts, also, the foundation, as it were, is laid with this tissue, in which the others subsequently appear. So uni- versally is it present, even in the adult fabric, that, if it were possible to abstract all the others from it, the original form would still be retained, except where it would give way with its own weight. 74. But, although cellular tissue is, in its regular state (of which the pith of young twigs, or the pulp of fruits are charac- teristic examples), soft and spongy in its character, it does not MODIFICATIONS OF CELLULAR TISSUE. 63 FIG. 23. ROUND LARLY IN CIRCLES. always remain so, but often acquires considerable hardness. This is the case, for example, in the prickles of .the Rose and other plants, which are merely connected with the cuticle, and are not prolonged from the wood beneath. It is the case also in the stones of the Plum, Peach, Cherry, c. ; and in the gritty matter in tjie centre of the Pear. In all these parts, the processes of vegetation are no longer going on ; but the power of firm resistance is re- quired in their place. This is effected, by the deposition of solid matter within the cells. Sometimes the new product lies in regular layers, one within another, covering the whole membrane ; sometimes it is deposited in what ARRANGED , , .... appears a less regular manner, certain points of the membrane being left uncovered by it. In this last case, however, an additional object is attained; for the cells, though the greatest part of their walls is so much thickened, are still in a degree permeable to fluid, through the spots of the membrane on which no deposit has taken place. These spots in the walls of con- tiguous cells generally correspond with each other ; so that fluids can find their way from one cell into the cavities of the neighbour- ing ones, though so large a pro- portion of their contents has be- J COHie SOHd. When tllC Walls Of 11 u v j.i_ J.L j cells have *>* thus strengthened j n particular parts, the membrane has a dotted appearance ; the thin- nest portions seeming almost like perforations. 75. The size of the cellules of this tissue is extremely variable ; they are usually from 1-300 to 1-500 of an inch in diameter; but may be found of all sizes, from 1-30 to 1-3000 of an inch. One Fio. 24. SECTIONS OF CELLS STRENGTH- ENED BY INTERNAL MATTER IRREGULARLY DEPOSITED ; the shaded portion indi- rates the remaining cavifies : a, cells from the gritty centre of the pear ; &, cells from the stone of the plum. 64 WOODY FIBRE. of the most interesting modifications of it, is found in the Sphag- num or Bog-Moss ; and in the coverings of some seeds. This consists in the presence, within the membranous wall of the cell, of a spiral fibre, coiling from one end to the other. In some of the seed-coats in which these spiral cells exist, the membrane of the cells is so delicate as to be easily dissolved away ; so that, if a portion be put into water, the fibres spring out very beautifully by their own elasticity. 76. The next form of elementary tissue to be described, is that called Woody Fibre. It has received the name of fibre, because it always exists in an elongated form, and several of the tubes of which it consists, adhere together conti- nuously, so as to form cords. This is seen in the common flax thread, for example. If the finest thread that could be separated with the naked eye, were submitted to a microscope, it would be seen to consist of several other fibres adhering together ; none of these have any great length ; but by the manner in which they adhere, side by side, and end to end, a continuous cord is produced. Each of these minute fibres, when more closely examined, is seen to consist of a slender transparent tube, tapering to a point at each end. It thus resembles a greatly elongated cell. It differs from cellular tissue of similar BUNDLE form, in the much greater strength of the membrane K FiI DY forming the walls of the tubes >* though it is at the same time thinner. There are many intermediate forms, however, between one and the other. Woody fibre is evidently destined to convey fluid in the direction of its length, and is easily permeated by it. Minute openings have sometimes been detected, in the points of the tubes, so as to connect one cavity with another, and thus to render the passage of fluid more easy. It is, however, especially destined to give firmness and elasticity to the parts of the structure which require sup- port ; and we almost constantly find vessels protected by it, wherever they exist. 77. In all plants with permanently- elevated stems, this tissue is very abundant in the adult state. It forms a large proportion MODIFICATIONS OF WOODY FIBRE. 65 of the wood of the stem and roots; it partly composes the leaf- stalk, midrib, and veins of the leaves, and may even be traced in flowers ; to many fruits, also, it imparts firmness and consist- ence. When no longer required for the conveyance of fluid, additional firmness and toughness are given to it, as to cellular tissue, by the deposition of various secretions within its tubes ; and it is in the presence or absence of these, that the difference exists between the heart-wood and sap-wood of a trunk (. 131). The woody tubes of the former are entirely choked up with the hard matter deposited in their cavities ; and the sap rises through the latter only. This hardened tissue may be in some degree compared to the cartilage or gristle of animal bodies. 78. A peculiar form of woody fibre is found in the stems of resinous woods, especially the Pine and Fir tribe. The diameter of its tubes is much greater than that of any other woody tissue ; and they alone perform the office of transmitting the sap upwards through the stem ; the wood of these trees being destitute of the ducts or canals (presently to be described), which in other kinds of trees assist in this function. But it is by a peculiar set of dots seen along their course, that these woody tubes may be readily distinguished from all others. These dots appear to be produced, by the formation of certain little bodies between the adjacent tubes ; and as the tubes are closely pressed toge- ther, these bodies (the nature of which FlG - 2 & GLANDULAR WOODY is not certainly ascertained) project into * A DKAL SHAVINS * the cavities of the tubes between which they lie. "Whatever be their character, they are of great interest, as aiding to establish the true nature of Coal. 79. That this substance had a vegetable origin, has long been generally admitted ; but from the comparative frequency and per- fection with which the remains of Ferns occur in it, it has been supposed to have been produced by the decay of vast forests of this tribe of plants. As Ferns do not form resins, however, this hypothesis would not account for the large quantity of bituminous matter which coal contains ; and hence it was supposed that coal 66 ORIGIN OF COAL. SPIRAL VESSELS. must have been formed from resinous woods, even though the remains of such were very scanty and imperfect. Now on apply- ing the microscope to transparent sections of such fragments of coal, as most distinctly exhibit the fibrous structure, it is seen that they present the character which has been .described, as peculiar to the resinous woods, the glandular form of woody fibre, as it is technically termed ; and hence it is established beyond doubt, that the immense masses of coal which now contribute so much, in every way, to the comfort and the social improvement of the human race, are but the remains of vast forests, probably the growth of many successive centuries, which chiefly, if not en- tirely, consisted of trees of the Pine and Fir kind. It is even possible, by the peculiarities of the arrangement of the dots, to say which of the subdivisions of that tribe at present existing, those primeval trees most nearly resembled. The reason why the remains of Ferns have been so well preserved, whilst those of other plants and trees should have lost all definite structure, has been already explained (. 26). 80. The third kind of primary tissue, is that denominated the Vascular. Its typical form is the Spiral Vessel, which is only found in Flowering-Plants ; but modifications of this exist in the lower tribes. The essential character of the Vascular tissue is the possession of a spiral fibre, coiling more or less regularly within its thin membranous tubes, from one extremity to the other. The true spiral vessel much . resembles the woody fibre in form, being a long narrow tube drawn to a point at both ends. But the membranous wall is much thinner, and is easily torn asunder. The spiral filament is usually single ; it is a b sometimes, however, double, or even triple : FIG. 27- PORTIONS / OF SPIRAL VKSSELS: and in the very large spiral vessels 01 the Chinese ^rS S Pitcher-Plant (Nepenthes, . 242) it is quad- partly drawn out ; ru pl e . These tubes in their perfect state contain 6, from Nepenthes, . * . with the quadruple air only, which finds its way from one to an- fibre - other, like fluid through the woody tubes. They SPIRAL VESSELS. AIR-TUBES OF INSECTS. 67 are found in the leaf-stalks, from which their spiral fibres can be uncoiled in the manner already described. They are found also in a delicate membrane, surrounding the pith of stem which possess one (. 135) ; and in the midst of the woody bundles which form the strings of such stems as the As- paragus. From this plant, indeed, they may be obtained more readily, perhaps, than from any other. If a stem be boiled, or softened by soaking in water for some time, and these bundles be separated from the soft tissue which surrounds them, the parts of each may be further separated from each other, by rubbing them, with a little water, between two plates of glass. On look- ing at them with a magnifying-glass, some portions of these bundles will be seen to present a dark appearance, if still under water. This is caused by the air they contain ; since bubbles of air in fluids viewed with the microscope, will appear dark to the observer, for reasons which will be mentioned in the Treatise on Light. If one of these threads be then carefully torn, with a pair of small needles fixed in handles, into finer ones, whilst under a powerful single magnifier, it may be separated into the individual spiral vessels which compose it, just as the thread of flax may be resolved into its woody tubes. 81. It is an interesting circumstance, that the air-tubes of Insects are formed upon nearly the same plan with these spiral vessels of Plants. The former consists, like the latter, of an external membrane, which is main- tained in its tubular form, in spite of pressure from without, by the elasticity of a fibre, spirally coiled in its interior. The principal difference between the two structures is, that the air-tubes of Plants are closed vessels, and that their con- tents find their way gradually from one to another, BRANCH^ 1 AIR- permeating the delicate membrane of their walls; VESSEL OF INSECT. and that they give off, therefore, no branches : whilst the air- vessels of Insects, whose office it is to convey air with great rapidity into all parts of the structure, form a set of continuous tubes, which branch and ramify with the most wonderful minute - F2 68 SPIRAL AND ANNULAR DUCTS. ness, even in the smallest organs of the smallest Insect (ANIM. PHYTSIOL. . 320). 82. There are other kinds of tissue which must be classed under the same head, but which do not serve the same purposes, or possess the same structure. Instead of tubes drawn to a point at each end, we not unfrequently meet with long continuous cylindrical canals, which serve for the conveyance of fluid, in- stead of for the passage of air ; these are called Ducts. There are several varieties of them ; of which those will be first de- scribed, which evidently belong to the type of Vascular tissue. In Ferns (which have no true spiral vessels), we find Ducts, which very closely approach the spiral vessel in character ; having an unbroken coil of spiral fibre throughout their whole extent ; but, besides the important difference that these Ducts, are long continuous tubes, they are further distinguished by the brittleness of the spire, which snaps if we attempt to unrol it. Such ducts are found in many other plants, and may be easily distinguished in the leaf-stalk of the Rhubarb. Another interesting modification of the spiral, is what is termed the scalariform or ladder- like duct ; this also consists of a spiral fibre inclosed in a membrane, but has a space intervening be- tween each turn of the spiral, so that the inner wall of the membranous tube is not entirely covered by it, but seems crossed by a series of bars. There are other ducts, again, in which the spiral is irregular, the coil sometimes terminating in a ring, and then commencing again, with perhaps the inter- vention of two or three rings (Fig. 29, b). Here it would seem, as if the membrane had grown faster than the spire could follow it ; so that the fibre, not being elastic, had been occasionally broken. In other ducts, again, we find no traces of a spiral fibre; but the membranous walls are distended by rings ft, spiral, with a t intervals sometimes tolerably regular. These are vRia" a, annu- called annular or ringed vessels (Fig. 29, a). The lar throughout. transition from the spiral to the annular vessels is FIG. 2D. STRUCTURE OF DOTTED DUCTS. 69 well seen, in the bundles of Vascular tissue in the petiole of the leaf of Ground-Ivy and other plants. 83. These two forms are especially interesting, from the analogies which can be found to them in the Animal structure. The close correspondence between the spiral vessels, and the trachea or air-tubes of Insects, has been already pointed out. On the other hand, the annular duct corresponds with the wind- pipe of higher animals ; the membranous walls of which are pre- vented from falling together, by means of rings of cartilage dis- posed at regular intervals. And the half-spiral half-annular duct, which is the intermediate form in plants, precisely corresponds with the structure of the wind-pipe of the Dugong (one of the Whale tribe), in which we find a spiral cartilage^ terminating at intervals in rings. 84. There are other forms of ducts, again, in some parts of which the traces of the spiral structure are very obscure ; whilst in other portions of the same tube, they can be easily distin- guished. In these it appears as if the spiral fibre had been broken up into small fragments, and that these had served as centres round which new deposites had accumulated; so that they had grown irregularly together, leaving interspaces in which the membrane is uncovered (as in the dotted duct) by this secondary wall. In fact it often happens that a duct, which exhibits in one part distinct remains of the spiral structure, approaches the character of the dotted duct so closely in another part, that they can scarcely be distinguished ; and it is probable that the interior deposite which gives to the latter its peculiar cha- racter, may have originally taken place around the fragments of a spiral fibre. 85. In other instances, however, it seems clear that the ducts have originated in cells, which have FIG. 30. lain end to end, and have been made to commu- JJJJ," D OWED nicate with each other, by the breaking- down of DUCT, showing -''.., r that the dots are the partitions between them ; for the remains ol thinner spaces these partitions may be not unfrequently detected. of its wall& Sometimes these ducts remain, like the cells from which they 70 SPIRAL DUCTS. BRANCHING SAP-VESSELS. originated, of a simply membranous character ; but more com- monly, their walls are fortified by an interior deposite, which does not, however, entirely line them, but leaves the membrane bare at certain points, giving that dotted appearance already described in treating of the cells (. 74). Hence these vessels are commonly termed dotted ducts. It is through such as these, that the sap principally rises in the stem and branches, and is conveyed to the leaves. They are by far the largest vessels contained in the vegetable fabric ; and their open mouths are visible in almost any stem, when cut across. They are of par- ticularly great diameter, when the stem itself is small and long, but bears a considerable amount of leaves, as is the case in the Vine and the common Cane ; in these, their orifices at once strike the eye ; and, if the stem of a growing plant be cut across, the oozing of the sap from their mouths will be easily distinguished. 86. The office of all these ducts is the same, that of con- veying fluid. It is only in the true spiral vessel, that we find air. These varieties have been described with somewhat greater minuteness than may appear necessary; because the young ob- server who examines the vegetable structure for himself, as it is hoped that many will be led by these pages to do, will be liable to be perplexed by meeting with them, if not previously ac- quainted with their characters. 87. One other form of ele- mentary tissue now remains ; and this differs from all the rest. It is a system of branching vessels, con- fined to the under side of leaves, and to the bark, and serving only for the conveyance of the nutritious sap ; which is carried by it from the leaves, where it is produced, down the bark, and thence to all parts of the structure. The walls ^r*S: f these' branching vessels are ex- LATEX OR NUTRITIOUS juics. trcmely delicate, so that they can STRUCTURE OF THE CUTICLE. 71 be scarcely separated from the tissue around; hence it was. long supposed that the nutritious sap, or proper juice as it is gene- rally termed, flowed in mere spaces amongst other tissues, and not in distinct tubes. T.he existence of these, however, is now well established ; and there can be little doubt that, like the straight ducts, they take their origin from cells, the partitions between which are broken down, so as to form a complete net- work of canals. 88. In future chapters, the combinations of these tissues in the several organs, such as the Stem, the Leaves, the Flowers, &c. will be described ; but it may be well here to speak of one peculiar modification of cellular tissue which is seen in all these parts, that, namely, which forms the cuticle or skin in which they are enveloped. The existence of this is easily shown in many leaves without preparation. From the leaf of the common garden Iris, for example, it may be easily stripped, or from the under side of that of the London Pride ; and from every leaf it may be easily removed, after being soaked for a few days in water. This cuticle is found to be usually transparent and nearly colourless. If when separated it should appear coloured, this is due to the adhesion to it of some of the cellules of the fleshy portion (or parenchyma) of the leaf ; these will afford an oppor- tunity of examining the form and structure of these cellules ; and they may then be wiped away, leaving the membrane perfectly smooth and colourless on both sides. Now when this is examined with a sufficient magnifying power, it is seen to consist of a number of flattened cells in close contact with each other ; and these cells contain either air, or a colourless fluid. Their form is very different according to the kind of plant examined. Some- times they are of a regular oblong and their sides straight ; whilst in other instances they are of very irregular form, and lock into one another like the pieces of a dissected map. 89. Though the cuticle usually consists but of one layer of cells, it sometimes contains two or even three, especially in plants naturally growing in warm climates ; and in the Oleander four may sometimes be distinguished. Its office appears to be, to prevent the moisture of the soft succulent tissues beneath from 72 CUTICLE. STRUCTURE OF THE STOMATA. evaporating ; since, if they were to dry up, their vital properties would be lost. Accordingly we find it absent in plants which habitually live beneath the surface of the water, and from those parts of others which are usually submerged ; whilst it is present on those parts of the same plants, which are lifted into the air ; as well as on all the soft parts of those, which are habitually and entirely exposed to it. Its use is at once seen, when a portion of a plant destitute of it is exposed to the air ; it then speedily dries up and withers. On the other hand, the Oleander, exposed to the intense sunshine of tropical Africa, maintains its verdure, even in arid situations, by the great resistance to evaporation, which its thick and almost leathery cuticle interposes. The best mode of separating this cuticle, so as to become acquainted with its remarkable firmness, is to soak a leaf for a few days, in water rendered sour to the taste by a few drops of nitric acid ; and it may then be easily stripped off. But its different layers can only be seen by magnifying a very thin slice of the leaf cut across ; so that its thickness, not its surface, is exposed to view. 90. The whole of the softer portions of all plants growing in air is covered by cuticle ; and in the young plant the entire surface. It is only when the stem increases in diameter, and the bark becomes hard and rugged, and occasionally scales off, that the cuticle can no longer be distinguished. It is evident on young shoots as on the leaves, and may be traced downwards to the point of the root ; but this it does not cover. It also protects all the organs of which the flower is composed ; but it is absent at one point, for reasons hereafter to be stated (Chap, xii.) The walls of the cells of the cuticle are often of considerable thickness, giving firmness to the organ it covers: such is evident in the leaves of the Holly, the hardened edges of which are com- posed of cells continuous with those of the cuticle. 91. The tissues protected by the cuticle are not entirely cut off by it, however, from the external air ; for it has certain aper- tures of a very peculiar character, which open or close under the influence of light. These apertures are called Stomata (mouths). They are usually of an oval form, and bounded by two kidney- shaped cells containing green matter ; and it is by the expansion STRUCTURE AND SITUATION OF THE STOMATA. 73 or contraction of these, that the orifice is diminished or increased. Sometimes, however, the opening is round, and is bounded by a ring of four or five such cells; and in the very curious stomata of the Marckantia potymorpha^ one of the commonest of the Liver- wort tribe (. 32), there are five such rings, one beneath the other, the aperture resembling a funnel, and the lowest ring being the one, which regulates the amount of communication, between the chamber into which it opens, and the external air. Fro. 32. VIEWS OF STOMATA. A, vertical section of stoma of Iris ; a, a, green cells bounding the orifice ; b, b, cells of the parenchyma ; c, air chamber. B, view of the same from above ; a, a, green cells of the stoma, lying between long cells of the cuticle ; c, opening between them. C, similar view of a stoma of apple leaf ; a, cells of the stoma ; 6, 6, cells of the cuticle ; c, opening of stoma. 92. Stomata are always placed over interspaces in the tissue, which are called intercellular passages ; they are never found on the midrib or veins of a leaf, nor in fact over any hard woody portion of the structure. They are chiefly disposed over the soft green tissue of leaves and young shoots ; but they are found also on the parts of the flower. "When the leaves are absent, and the stem performs their functions, as in the Cactus or Prickly-pear tribe, stomata are found on its surface. They are generally most abundant on the under surface of leaves, and are sometimes altogether absent from the upper. This is partly due to the fact, that the tissue lying beneath the upper surface of leaves is so closely packed together, that there are scarcely any intercellular passages, into which the stomata might open ; whilst the tissue in contact with the lower cuticle is extremely loose in comparison, and abounds with such passages ; hence it is, that the colour of the upper surface of the leaf is usually so much deeper, than that of the lower. But in leaves of which the two sides are equally ex- posed to the air and light, such as those of the Iris, and of the common Flags growing by the sides of brooks, the general struc- 74 OFFICE AND FORMATION OF 8TOMATA. ture is nearly the same on the two sides, and the stomata are equal in number. Again in Plants, the circumstances of whose growth are such, that the atmosphere commonly comes in contact with the upper side only of the leaf, as in the case of the Water Lily, the leaves of which float on the surface of the water, the stomata are disposed on that side alone. 93. As there is no cuticle to protect the tissues of plants grow- ing altogether beneath the surface, so there is no occasion for stomata to admit the passage of air to these ; and accordingly in the whole tribe of Sea- weeds we find no vestige of them. Neither can they be distinctly traced in the Mushroom tribe, nor in Lichens ; but in the Liverworts they present themselves, in the most remarkably complex form which we anywhere witness ; in the Mosses they have only been detected on the stalk which bears the fructification ; whilst in most Ferns, as well as in Flowering Plants, they abound. 94. Of the very minute size of these curious organs, some idea may be formed from the fact, that in some leaves it is esti- mated that 70,000 occur in a square inch of cuticle. The largest known are about the 1-500 of an inch in length ; whilst the smallest are not 1-3000. Their function is evidently to allow of that limited evaporation of water from the soft tissues of the plant, which will hereafter be shown to be one of the most im- portant of the processes, by which the crude fluid absorbed by the roots is converted into the nutritious sap or proper juice. The influence of light upon the stomata causes them to open, whilst they contract and even close in darkness. 95. It has also been shown, that light has a most important influence on their first production. In the young plant of the Marchantia (. 33), when first separated as a kind of bud from its parent, no stomata or roots exist. It lias been ascertained by repeated experiments, that stomata and roots may be caused to develop themselves in either of the two sides ; the stomata being always formed on the upper surface, under the influence of light, and the root-fibres proceeding from the lower towards darkness. But if the surfaces be reversed after the respective organs have been developed to a certain point, so that the stomatu APPENDAGES TO THE CUTICLE. HAIRS. 75 be directed towards the ground, and the roots be made to rise into the air, the little plant will right itself, by twisting itself round, so as to bring its surfaces to their former position. Fur- ther, when plants of a higher description are grown in darkness, the stomata are developed very imperfectly, or not at all. Thus we have an example of the very important effects of the stimulus of light upon the vegetable structure, not only in governing its actions, but in influencing its development. 96. With the cuticle may be advantageously considered those appendages, which are developed from it, as hairs, prickles, stings, &c. The leaves and stems of many plants are covered with hairs, which is sometimes bristly, sometimes soft and downy, and some- times scattered very thinly. The structure of these hairs is various. Sometimes each forms but one long cell ; whilst in many other instances, every hair consists of a row of cells placed end to end, and sometimes these send off minute side branches. The analogy of these cells with those of the cuticle, is shown by the curious fact, that many plants are hairy, or not, according to the circum- stances in which they grow. Thus, when they are found in dry exposed situations, their stems stunted in growth, and their leaves FIG. 33. HAIRS AND GLANDS OP VARIOUS KINES,- a, gland surmounted by a hair; b, small gland at the top of a hair ; c and e, simple hairs ; d, branching hair. small, their surface is covered with hairs, as if the cells which 76 STINGS, PRICKLES. AIR-CHAMBERS. would have otherwise formed a larger cuticle had taken the shape of hairs : whilst in damp shady places, which favour the extension of the leaves and stems, their surface is quite smooth, all the material being then required to form cuticle. It will be shown hereafter (. 278) that the development of hairs on the surface of the leaves of plants growing in dry situations, favours the absorption of moisture. 97. Sometimes the hairs are tubular and pointed, and are fixed upon minute glands in the cuticle, which secrete an acrid fluid ; and if but very slightly touched, the reservoir at the base is compressed, and the fluid forced up through the tube, into the wound made by its pointed extremity. Such hairs are termed stings ; and the Nettle affords a familiar example of them. The prickles of the Rose and other shrubs are also appendages of the cuticle, with which they are stripped off, and from which it is easy to detach them. They are thus distinguished from thorns, which proceed from the wood of the branch, and which, as will be here- after stated, may be regarded as stunted leaf-buds. Prickles, after being once formed, and hardened by the process already described (. 74), undergo no subsequent enlargement ; and, accordingly, if the cuticle on which they are fixed should be extended, their base is not able to expand in the same propor- tion, and they drop off, leaving scars on the surface of the stalk. 98. Another interesting modification of cellular tissue, is that which surrounds the spaces or cavities, formed in certain plants for special purposes. Thus in the Duckweed, the leaves are pro- vided with a set of air-chambers, which give them great buoy- ancy ; and nothing can be more beautiful than the manner in which the walls of these cham- bers are built up of muriform cellular tissue. In other cases, t!lese -vifeappear to be formed CELLULAR TISSUE as receptacles for certain secreted IGO. 247 in seven years, and two crops are obtained in each year. The indigo, which seems to be nothing else than the chromule of the plant, is usually extracted by fermentation. The plants are laid in a vat, and covered with water ; and in about 18 hours they begin to swell, and to give off a large quantity of gas, the water at the same time acquiring a green tinge. This process is allowed to go on, until the colouring-matter of the vegetable tissue has been entirely yielded to the water ; but if it continue too long, so that any putrefaction take place, the dye is destroyed The fluid is then drawn off into another vat, where it is violently agitated, for the purpose of separating the pulp from the water. The former consists of little grains, which, during the process, turn from green to blue by attracting oxygen from the air ; and, by further processes, it is dried into a solid mass, constituting the indigo of commerce. Nearly all the indigo imported into Britain, is produced in the East Indies ; its amount averages about seven millions of pounds every year, of which, however, more than half is exported again, chiefly to the North of Europe and Italy. Owing to the great variation in the productiveness of the crops, the price of Indigo is almost constantly changing. In the season 1824-5, it was nearly 11s. 6d. a pound; whilst in the season 1829-30, owing to an over-abundant supply, it was only 4s. 4d. At the former rate, the value of the average quan- tity annually imported would be about four millions sterling ; and at the latter, scarcely above one and a half. 389. This valuable dye has so strong an attraction for almost every kind of fibrous texture, whether animal (as woollen or silk) or vegetable (as linen or cotton), that it will impart to it a permanent colour, without the assistance of a mordant*. In order to apply it, however, it must be dissolved in water ; and this can only be accomplished by a change in its chemical nature, which restores it to its original yellow-green colour ; the stuffs, after being dyed, change again to blue, by exposure to the * Mordants are substances used in dyeing and calico-printing, to hold together the particles of the texture dyed, and those of the dyeing material, when these have iiot a sufficient attraction for each other. If not so united, many colours would be washed off, as readily as they are laid ou. 248 , INDIGO, \VOAD. air. This process appears to injure in some degree the durability of the colour ; and it is preferable to apply the dye, when first separated from the plant. The brilliant blue cloths of Africa and China, which are superior in hue to those of any other part of the globe, are produced in this manner. 390. The juices of several plants, growing in the different countries of the East, are used by the natives of those countries, in the same manner as Indigo ; and might probably furnish a good substitute for it, if prepared with sufficient care. The use of Indigo as a dye, on a large scale, is comparatively recent. It was not until long after the discovery of America, that it was commonly employed in England ; and the use of it was forbidden by the governments of some European countries, from the fear that it would supersede the use of Wood, which was then very extensively cultivated. This dye was known to the Ancient Britons, who stained their bodies with it ; and it was the prin- cipal blue dye; until the introduction of Indigo. Its colour is much less lively than that of Indigo, but it is more durable ; hence it is commonly employed in union with that and other dyes, but seldom now by itself. Woad (I satis sativa) is culti- vated in many parts of Europe ; and is grown in considerable amount in Lancashire. Its stem is about three or four feet high, and about half an inch in diameter ; it divides into many branches, which are loaded with leaves. It is cut down with a scythe, when the flowers are about to appear ; and afterwards at intervals of about six weeks; three or four crops being usually obtained in one year. The plants are first washed, and then dried in the sun, without which they will begin to putrify, their green colour turning black. They are then conveyed to a mill, where they are ground into a paste. This paste is after- wards subjected to several processes, for the purpose of drying it. It is finally used nearly in the same manner as indigo ; with which, indeed, its colouring matter, if extracted in the same manner, is found to be nearly identical. 391. A Violet hue is easily given to cloth, by mixing blue and red dyes in any required proportion ; but there are some plants, which yield a violet or purple dye, without any admix- LOGWOOD. MADDER. 249 ture. The chief of these is Logwood, the produce of a tree grow- ing in the bays of Campeachy and Honduras, the native country of the Mahogany. When Logwood was first introduced into this country as a dye, the use of it was forbidden by Government, on account of its " deceitful" character ; the colour it communi- cated being fair to the eye, but speedily departing. The art of fixing it by mordants, however, being afterwards discovered, this substance came into general use ; and it is now imported largely from Jamaica, as well as from its original country. The part which yields this dye is the heart-wood ; this is hard and heavy, in consequence of the amount of secreted matter con- tained in it ; and it yields its colour readily to water, when this is boiled upon its chips. The deep violet or purple hue of the fluid, first changes to a yellowish tint, and finally becomes black ; but this change may be prevented by the use of proper mordants. The chief use of this substance, however, is in dyeing black, and in producing all shades of grey. The quantity imported into Britain in 1839 was 23,000 tons, the value of which was above 180,OOOZ. 392. The principal Red dye obtained from the vegetable kingdom, is Madder, the produce of the Rubia tinctoria, a plant which grows naturally in the Levant, and which is cultivated with success in the South of Europe ; its cultivation does not answer in England. The colouring-matter is obtained from the roots, and is not sufficiently formed until the third year ; the roots are taken up in the autumn, after the leaves have fallen off. They are then carefully cleaned, dried, and reduced to powder. A great variety of colours, varying from lilac to black, and from pink to deep red, may be produced by the application of different mordants to the stuff, before it is placed in the madder. These are partly due to the intermixture in this substance of two distinct colouring principles, a fawn and a red. The latter, if separated from the other, is much more brilliant ; and various processes have been devised for the purpose. The best of these requires that undried roots should be employed ; and they are largely imported into this country with this object. The quan- tity of madder employed in Britain in 1838, was upwards of five 250 BRAZIL-WOOD, ARCHIL. thousand tons ; and of the roots, more than four thousand. The value of these would be together about 600,000^. 393. Another valuable Red dye, is obtained from the wood of the Ccesalpinia crista,* commonly known as Brazil wood. Though abundant in that part of South America, the tree is a native of other parts of the world ; and it was known under its present common name, before the discovery of that country. And, in fact, the portion of that continent which bears the name of Brazil, was so named in consequence of the numbers of these trees, which were found growing there. As in the case of Log- wood, it is only the duramen (. 131 ) of this tree, which is of any service ; the remainder being colourless. The colour ob- tained from this wood is brilliant ; but it is not so permanent as that of many other substances. It is generally used to heighten the effect of other dyes. Red ink is commonly made, by boiling this wood in beer, wine, or vinegar, to which alum has been added. Of late years the consumption of this wood in Britain has much diminished ; whilst that of another kind, termed Peach-wood, or Nicaragua- wood (so named from the Gulf of Nicaragua, whence it was first imported into England), has greatly increased, so as to be now nearly double the first. The colour obtained from it is brighter, and more delicate, than that yielded by Brazil-wood. 394. Another red dye, now largely employed in England, is obtained from a Lichen, commonly termed Orchilla., which abounds in the Canary and Cape de Verd Islands, and which is sometimes found (though of inferior quality) on the rocks of Guernsey and the Isle of Portland. The plant is usually im- ported without any preparation ; it is afterwards dried and reduced to powder, and then submitted to some chemical pro- cesses, which produce from it the beautiful liquid dye, known as Archil. It is seldom used by itself, as its colour is not perma- nent ; but it is chiefly employed to give a brightness to the * An allied species of this tree, the C. pluviosa, also a native of Brazil, is re- markable for a constant flow of water from the points of its leaves, which falls ijo\vn in drops, like a shower of rain. ' ALKANET. WELD. 251 hues of stuflfe, dyed with other substances. Another species of Lichen yields the dye termed Cudbear. Several other red dyes might be enumerated, which are used in small quantities for particular purposes. Among the most important of these is Alkanet, which is obtained from the roots of the Anchusa tihctoria, a native of the Levant and the warmer parts of Europe, but grown also in England. This colouring principle is not soluble in water; but it gives a deep red colour to oils, wax, and unctuous substances. It is consequently used chiefly to colour oils, ointments, lip-salves, &c. ; and it is sometimes applied to the staining of wood, when dissolved in oil. Notwithstanding the apparent insignificance of these purposes, above 50,000 Ibs. of it are annually imported into this country for home use, besides what is raised in Britain. 395. Many good Yellow dyes may be obtained from plants ; and the most important of all those used in Britain, is procured from a plant of native growth, Weld, or Wold, or (as it is sometimes called) Dyer's-weed. This grows spontaneously in many parts of the country, on uncultivated wastes ; and it is a very hardy plant, preserving its verdure through frost and drought. It is nearly allied to the Mignionette ; but is a much taller plant, attaining the height of three feet before blooming. It takes two years to come to maturity, and is gathered whilst the seed is ripening. The plants are dried, and then transferred to the dyer, who at once extracts the colour by boiling ; there is reason to believe, however, that the seeds contain the really important part; and that, if they be saved, the trouble which arises from the bulk of the whole plant, may be avoided. The colour is also separated, in the form of a yellow powder, for the use of the paper-stainers, who employ much of it. A much larger quantity of weld is used in England, than fs supplied by cultivation ; and it is consequently imported from abroad. This is much to be regretted ; as there is good reason to believe, that it will thrive and yield a handsome profit, on lands so poor as not to be profitably cultivated in any other way. 396. Another very excellent yellow dye is obtained from the bark of the Quercw tinctoria, or Quercitron, a species of 252 FUSTIC, ARNATTO, SAFFRON. Oak common in America, the timber of which is employed largely in building. This bark is employed in the United States for tanning ; and its colour being considered a defect, this is removed by a chemical process. More than a thousand tons of it, however, are annually imported into Britain : and it is here much valued, on account of the number of different shades of colour, which it may be made to produce, as well as on account of its superior durability. A much greater demand exists, how- ever, for the dye termed Fustic ; which is extracted from the wood of a species of Mulberry tree, that grows spontaneously in Brazil and the West Indies. It does not yield above one- fourth the amount of colouring matter obtained from Quercitron, and its colour is not so lively ; but it is more efficient in combi- nation with some other dyes, and is used with indigo to dye Saxon green, and with salts of iron for drab. 397. Arnatto is another dye of a reddish yellow, employed for particular purposes ; it is obtained from the crimson pulp lying between the husk and the seeds of the Arnatto tree, which is a native of both the East and West Indies. It is brought to this country in cakes, which are made by boiling down the pulp ; and these are of a brownish red, giving a bright orange, when dissolved in water with the addition of an alkali. Its hue is not permanent, however ; and it is seldom employed by itself, except for giving colour to cheese ; for which it is valued, on account of the ready communication of its colour, without im- parting any unpleasant flavour or unwholesome quality. One of the most beautiful yellow colouring substances, is that known as Saffron ; but it is too expensive to be much employed by dyers. Its chief use is in medicinal and culinary preparations, to which it imparts its brilliant hue and agreeable flavour. Saffron is the produce of a kind of Crocus, which is cultivated in England, as well as in France and Spain. This plant flowers in October ; and the flowers are gathered, even before they are full-blown. The stigmata^ or points of the pistils (. 434), of these flowers, are then picked off; and the rest of the flower is thrown by as use- less. These little bodies, constituting the Saffron, are next very carefully dried, and pressed between paper. Its high price re- TURMERIC J SUMACH. 253 suits from the very small amount of it produced, even on good land ; even when the roots are planted thickly, the average quan- tity for the whole three years (beyond which they should not be allowed to remain in the ground,) is not above 26 Ibs. per acre. Turmericis sometimes used as a substitute for Saffron, the colour it produces being very bright, though deficient in durability. This dye is procured from the roots of an East Indian plant named Curcuma longa, which has also been cultivated in the West Indian Islands with success. These roots are not unlike ginger, either in figure or size ; and the dye brought to this country consists simply of the roots, either whole or reduced to powder. It is sometimes used to give brilliancy to other hues ; and is employed as an ingredient in yellow varnishes. Several other plants affording yellow dyes might be enumerated ; but the fore- going are the chief. It may be mentioned, however, that the clothiers of some parts of Lancashire and Yorkshire, make use of common Heath for their yellow and orange dyes ; this, with a proper mordant, is said to produce on woollen cloth a more beau- tiful colour, than either weld or quercitron ; but it is not so permanent. 398. Almost all Vegetables contain more or less colouring matter, capable of affording/awm colours, or brownish hues inclin- ing to yellow, red, or green. The dye chiefly employed for this purpose, however, is obtained from the Sumach, a native of the south of Europe and of Syria. The shoots of this plant are cut down every year, close to the root ; and after being dried, they are reduced to powder by means of a mill. An infusion of this powder yields a greenish fawn colour, which may be altered by mordants. The principal use of Sumach, however, is in dyeing black, in the manner presently to be described. The colouring matter of the husks of walnuts forms an excellent dye for wool ; and it is much esteemed among the French dyers, for the agree- able and durable hues it affords without the assistance of mor- dants. In order to obtain this colouring matter, the husks are kept in water for a year or two ; after which they give out much more of it than when fresh. The Henna-juice, which is em- ployed by the ladies of the East for the purpose of staining their 254 BLACK DYES. OAK GALLS. nails, is a very permanent brown dye ; the colour not disappear- ing, until the substance of the nails is changed by growth. It is also employed for dyeing ordinary stuffs ; but it has not been introduced into this country. 399. The Vegetable kingdom affords several substances, which are capable of themselves producing a permanent black dye ; but a much larger amount of such materials is required, than could thus be obtained ; and the black colour of our cloths and stuffs is procured by a chemical process, of which one im- portant ingredient is furnished by Plants. This process consists in adding gallic acid to a solution of iron ; by which an insoluble bluish black substance, the gallate of iron, is immediately formed. If a cloth, therefore, previously steeped in a solution of iron, be jmmersed in an infusion of any vegetable matter containing gallic acid, a black dye will be communicated to it. Almost all vegetable substances having an astringent taste, contain gallic acid ; but especially the Oak tribe. It is from the abundance of this acid in the Gall-nut (which is an excrescence resulting from a kind of inflammation, excited by a wound of the soft tissue of the leaves or young shoots by the gall-fly), that it takes its name. Gall-nuts are not, however, formed upon the Oak of this country;* but upon a smaller species, which grows wild in the countries bordering on the Mediterranean. They are usually pounded and then boiled in water, in which the eloth is steeped ; and this is afterwards placed in the solution of iron (commonly termed cop- peras). The colour thus communicated is not a deep black, but rather a dark blue. It is improved by logwood, which is boiled with the copperas ; and the stuff should have been previously dyed of a deep blue, with indigo. A similar process is employed in the manufacture of common black writing-ink, which essen- tially consists of gallate of iron suspended in water by means of a small quantity of gum ; and logwood is here also added to improve the colour. Galls are imported from the East Indies, as well as from Turkey ; but of late years they have been in less * The Oak Apples, however, are similar formations ; as are also various other excrescences, formed upon different parts of the Oak, which is infested by several species of Gall-fly BLACK DYES. VEGETABLE ACIDS. 255 demand, in consequence of the introduction of another source, from which gallic acid may be obtained at a much cheaper rate. This is in the cups of the acorns of the Yelani Oak, a species which grows abundantly in Greece, and in the maritime parts of Asia Minor. These cups, which do not contain gallic acid in the same proportion as gall-nuts, are known in commerce by the name of Yalonia ; but in consequence of their cheapness (being only about one-fifth the price of galls) the consumption of them is very great. During the year 1830, the quantity of gall-nuts employed in England was 2,297 cwt. ; whilst that of Yalonia was 86,538 cwt. Many other astringent substances may be used as black dyes with iron ; and a good deal of the Sumach imported into Britain is used for this purpose, as are also walnut husks in France ; the shells of chestnuts, too, have been employed, although not profitably. In India, the juice of the fruit of the Myro- balans, which is not unlike a plum, is used for dyeing black with iron ; and when the pulpy portion is freed from the stone, which is useless, it contains more gallic acid than an equal weight of galls, and might be made a profitable article of commerce. 400. From gallic acid, we may naturally proceed to speak of the other acids, which are produced by Yegetables. These are all, like the foregoing substances, formed by the plant itself, from the elementary bodies it receives as food ; and thus they may be regarded as true products of vegetable secretion, and not as merely separated by the plant from the surrounding soil. In this last light we must regard the earths and alkalies obtained from plants, and not as products of their secreting processes. The acid which is employed in largest quantity, is the Tartaric. This is obtained from the crust that is deposited by wine, when kept a long time ; the amount of which depends, chiefly, upon the degree of acidity in the wine. The crust which goes by the name of Argol, chiefly consists of tartaric acid in combination with potash, forming what is commonly known as Cream of Tartar ; and this requires to be purified from its colouring- matter and other impurities, before it can be employed in the arts. The acid is easily obtained in a separate form by chemical processes ; and it is employed for many purposes, which cannot be 256 OXALIC ACID ; CITRIC ACID. answered by the cream of tartar. Its chief use is in many processes of dyeing and calico-printing. 401. Another vegetable acid much used in the arts is the Oxalic, which is well known as a violent poison. From the resemblance of its crystals, in size and general form, to those of Epsom salts, it has not unfrequently been administered by mistake, with the most dreadful consequences. This acid is found united with potash, in the leaves of the "Wood-sorrel and common Sorrel ; and the oxalate of potash is prepared from their leaves in large quantities, in Switzerland and the neighbouring countries, where these plants grow abundantly. Its long needle- like crystals may be seen lying amongst their tissues, if a thin section of the stem or leaf-stalks be placed under the microscope. This salt is known as Salt of Sorrel ; but it is sometimes sold under the name of Salt of Lemons, to which title it has no right whatever. The acid may be separated from it, as in the former instance ; and it is employed for many purposes by the dyer and calico-printer ; as well as for removing the stains of ink, iron- moulds, &c., which it does without injuring the texture of the stuff. 402. The acid which gives sharpness to the juices of lemons, oranges, limes, and a variety of other fruits, and is known under the name of Citric acid, is likewise one which has many im- portant uses, besides that of imparting a peculiarly refreshing character to these juices. It is largely employed by calico- printers, who now usually import their own lemon-juice, and concentrate it for themselves. At one time, the citric acid, which is not combined in the juice with any earth or alkali, was obtained by chemical processes in separate crystals ; but it is now found, that the impurities of the juice do not interfere with its use in calico-printing ; and it is employed for this purpose, almost in its original state. For other purposes, however, pure citric acid is required ; and this is partly made in Sicily, where Lemons are abundantly produced, and from which island, with the neighbouring continent of Italy, the greater part of the juice consumed in Britain is imported. Pure citric acid is used in the preparation of the best morocco Leather ; for improving a beau- CITRIC ACID; PYROLIGNEOUS ACID. 257 tiful scarlet dye, produced by a preparation of tin ; and for altering the hue of some colours, which are exclusively used in the dyeing of silk. Besides its use in the arts, Lemon-juice is very largely used in the navy, for the purpose of preventing the complaint termed Scurvy ; which is very apt to be brought on by the continued use of salt meat by confinement, but parti- cularly by the want of fresh vegetables. During long voyages, a regular allowance is made to each man, which he is required to use as a medicine. This, however, has been now rendered less necessary than formerly, since the art of preserving meats and vegetables in a fresh state has been brought into general use. Citric acid exists in many of our commonest fruits^ such as the cranberry, cherry, red whortleberry, and the hip of the wild- briar ; whilst in the red gooseberry, the currant, the bilberry, the black cherry, the wood strawberry, and the raspberry, it is mixed with an equal proportion of malic acid, which exists alone in apples, pears, and other fruits. It is interesting to notice the uses of the acids in these situations. It has been formerly stated, that gum or starch, when acted on by a vegetable acid with a moderate degree of heat, is converted into sugar ; and this is exactly what takes place in fruits during ripening, which pro- cess consists in the conversion of the starch of the hard unripe fruit into sugar, without any diminution in the amount of acid, which is sometimes indeed really increased, whilst its taste is concealed by the sugar. 403. One more vegetable acid may be mentioned; though it probably does not exist as such, in the substance from which it is obtained, but is formed by the heat employed to set it free. This is pyroligneous acid, formerly called acid spirit of wood, which is procured by subjecting wood in closed iron retorts to a strong red-heat ; the vapour that is given off, partly consists of this acid, mixed with tarry matter, which is separated by a second distillation. This acid, which in some degree resembles very strong vinegar, is used by the dyer and calico-printer ; and it is also employed for making pickles and other culinary pre- parations, in which an acid of great strength is required. The impure acid has been found to possess, in a remarkable degree, 258 EVIDENCES OF A DESIGNING PROVIDENCE. the power of checking the putrefaction of animal substances, even when applied in very small quantity ; this is due, however, not to the acid, but to a certain ingredient in the tarry matter, which is mixed up with it, and which, when separated under the name of creosote, is now well known as a valuable medicine, especially for the relief of tooth-ache. The discovery of the influence of this substance in controlling putrefaction, would be of great value, if it were not, that, by no subsequent process of cooking, can the tarry flavour communicated by it to the meat, be got rid of. 404. Having thus passed in review some of the most im- portant products, afforded by the secreting processes of Plants, for Man's use and benefit, and having been obliged to confess our almost entire ignorance of the processes they serve in the Vege- table economy, we might proceed to the next division of our subject ; but it would be wrong not to pause here for a moment, to contemplate the important inferences which may be drawn from the foregoing details, in regard to the Power, Wisdom, and Goodness of the Almighty Designer. His Power is scarcely anywhere more remarkably displayed, than in the immense variety of products, which are elaborated out of the three simple elements oxygen, hydrogen, and carbon, by processes, which, as far as we can understand them, appear to be of the most simple description. His Wisdom is strikingly evinced in the diffusion of these products over the whole globe ; so that there is scarcely a country, which does not naturally contain those, which may be most useful to its inhabitants. And his Goodness is peculiarly manifested in the adaptation of these pro- ducts the formation of which (we can scarcely doubt, although we cannot understand) must have an object as regards the plants themselves to the use of Man, in ministering to those various wants, which have sprung out of his condition as a rational being, endowed with higher faculties and more varied powers of enjoyment, than those of the beasts which perish, and yet de- pendent for the most favourable use of these, upon the judicious EVIDENCES OF A DESIGNING PROVIDENCE. 259 employment of the means, with which a bountiful Providence has abundantly supplied him. The nourishment of Man's body in health, his restoration in disease, the clothing that covers him, the varied hues which he can communicate to this, the colours which delight his eye in the ve-rdant landscape, or in the skilfully painted picture, the odours which refresh his senses, the timber of which his habitations, his manufactories, his ships, are partly or wholly constructed, these are but a few of the provisions, which the benevolence of the Creator has made for his comfort, in the organisation of the Vegetable World. Who, then, shall say, that it is less fertile in the evidences of a Designing Provi- dence, than the Animal Creation ? CHAPTER XI. OF THE PRODUCTION OF LIGHT, HEAT, AND ELECTRICITY BY PLANTS. MOTIONS OF PLANTS. 405. IT has been already stated that, by the operation of these agents upon the Vegetable system, are chiefly maintained those changes which make up the life of each being. (. 9.) If Light be withdrawn, several of the most important of these are speedily checked. If Heat be suspended, all of them directly cease. With regard to the influence of Electricity, less is known, and nothing can be positively stated. But Light, Heat, and Electricity are not only required by Plants as conditions of their growth ; but are sometimes produced by them. 406. There are few instances in which Light is evolved from Itving Plants ; but these few are very curious. Many flowers, especially those of an orange colour, such as the Sun-flower, Marigold, Nasturtium, Sec. have been said to disengage light in serene and warm summer evenings, sometimes in the form of sparks, sometimes with a steadier but more feeble glow. Light is also emitted by certain species of Fungi, especially those which grow in moist and warm places, where light is entirely excluded, as in the depths of mines. The light is perceived in all parts of the plant ; but chiefly in the young white shoots. It ceases if the plant be deprived of oxygen, either by being placed in a vessel from which the air has been exhausted, or in some other gas ; and it re-appears, when the plant is restored to air. No iuminousness is perceived after the death of the plant. It would seem probable, therefore, that this extrication of light is in part connected with that conversion of oxygen into carbonic acid, which, as already mentioned, takes place very rapidly in flowers, HEAT OF ANIMALS AND PLANTS. 261 and in the whole substance of the Fungi (. 290.), and which may be regarded as a sort of slow combustion. An evolution of light has also been observed to take place, from dead and decaying wood of various kinds, particularly that of roots ; and also from Fungi whilst decomposing. This corresponds with the luminousness of certain Animal bodies after death. 407. It is well known that the higher Animals alone possess the power, of keeping the temperature of their bodies up to a certain fixed standard ; and that in the lower tribes, the heat of the body varies with that of the atmosphere, being frequently but a very little above it ; so that these, giving to the touch a sensation of cold, are termed cold-blooded animals. Still, they have some power of generating or producing heat, which is shown by their power of resisting the influence of extreme cold for a long time. In regard to Plants, much doubt has been enter- tained at different times, whether they could be said to have a proper heat or not ; or whether their temperature is not entirely dependent upon that of the atmosphere. But this doubt has resulted from a very limited view of the processes of the Vegetable Economy, against which it is desirable to guard the young reader. 408. The production of heat in Animals is principally dependent upon the conversion of Oxygen into Carbonic acid, by its union with the carbon thrown off in respiration ; and just as the rapid combustion of charcoal in oxygen gives out a great degree of heat, so does the slower process of union in which the respiration of human beings really consists, disengage heat more gently. (ANIM. PHYSIOL. CHAP, vi.) Now in Plants this process of respiration takes place so slowly (in comparison with Animals), and from a surface so openly exposed to the atmo- sphere, that it could scarcely be expected that there should be any sensible elevation of the temperature of the part from th'S source ; especially when it is considered that a constant loss of heat is taking place by evaporation.* * See TREATISE ON HEAT. This fact is readily understood, by pouring a little water, a little spirit of wine, and a little ether, one after another, upon the back of the hand. Although they may have been all of the same temperature, the 262 PROPER HEAT OF PLANTS. 409. Some recent experiments, however, made with an apparatus that would indicate extremely slight changes of tem- perature, have proved that the process of Respiration in Plants is accompanied by a disengagement of heat; but in order to establish this, it was necessary to compare the temperature of a living plant with that of a dead one, having the same proportion of moisture at its surface; since in this way only, could the true effect of respiration in producing heat be known, whilst the evaporation was continually preventing the manifestation of it, by cooling the surface. In this manner it was found, that the heat of the surfaces of plants is raised by their respiration, from 1 to 2| degrees above what it would otherwise be. 410. It has long been observed, that the interior of large trunks possesses 'a temperature more uniform than that of the surrounding air ; being cooler than the atmosphere in summer, and warmer in the winter. There are at least two causes of this occurrence. Wood is a slow conductor of heat ; thus, if a piece of stick and a tod of iron of equal sizes have one end heated in the fire, the farther end of the stick will be nearly cold, whilst that of the iron is too hot to be handled. Further, the conducting power of wood is still less across the grain (or through the stem), than with the grain (or along the stem) ; so that changes in the external air will not readily affect the centre of a large trunk ; and, accordingly, it is found that, the larger the trunk on which the observation is made, the greater is the difference between its state and that of the air. The other reason is, that some motion of the sap takes place even in winter ; and the fluid taken up by the roots principally comes from a depth in the ground, at which, from the bad-conducting power of the soil, the temperature is nearly uniform throughout the year. 41 1. The evolution of heat by Plants is most evident, at those periods of their existence, in which an extraordinary quantity of carbonic acid is formed and given off. This is the case during the germination or shooting-forth of seeds ; and though the heat hand is cooled least by the water, more by the spirit, and most by the ether, in proportion, in fact, to the rapidity with which these fluids respectively pass off in vapour. HEAT OF SEEDS AND FLOWERS. 263 produced by a single seed is too soon carried off by surrounding bodies, to be perceptible, it accumulates to a high degree, when a number are brought together, as in the process of malting (. 283,4), in which the thermometer has been seen to rise to 110. The same may be said of that other period of vegetation, in which an extraordinary amount of carbonic acid is evolved, that of flowering (. 285). It is evident that, from the little substance of the parts thus heated, and the large amount of sur- face they expose to the air, the heat will be carried off by the atmosphere, almost as rapidly as it is produced. Still in some flowers, a considerable amount of heat can be proved by the thermometer to be disengaged ; thus, a Geranium has been found to possess a heat of 87, when the air around was at 81. 412. As in the case of seeds, however, the production of heat is most sensible, when a number of flowers are crowded together ; and this is still more the case, when they are inclosed in any general covering, as are those of the Arum family. In these the flowers are small, and are very closely set upon a stalk, which is called a spadix ; and the whole cluster is sur- rounded by a large leafy sheath called a spathe. It is in these flowers, that the size of the fleshy disk is the most considerable, and the quantity of carbon to be united with oxygen is therefore the greatest ; and the combination of this cause with the other occasions the temperature of the clusters to be raised very high. A thermometer placed in the centre of five spadixes has been seen to rise to 111, and one in the centre of twelve to 121, while the temperature of the external air was only 66. The increase of temperature commences with the opening of the flower ; and it is greatest at the time of the shedding of the pollen (. 433). 413. That the development of heat in these cases is owing to the conversion of carbon into carbonic acid, is proved by two kinds of experiments. In one, the cluster of flowers was placed in pure oxygen, by which this change was performed much more rapidly than in common air ; and the heat given out was much greater, than that evolved by a flower-stem at the same stage, in common air. On the other hand, a spadix being put into 264 DEVELOPMENT OF ELECTRICITY BY PLANTS. nitrogen (the gas which forms the greatest part of common air, seeming to have for its object to dilute the oxygen, which by itself would be too powerful for the support of animal and vegetable life), the formation of carbonic acid was altogether checked, and no heat was given off ; although the opening of the flower, and the shedding of the pollen, took place to all appear- ance as usual. 414. So little has been satisfactorily ascertained, regarding the connection of Electricity with the processes of Vegetable growth, that it seems undesirable here to dwell upon the mani- festations of this agent which sometimes occur. It may be stated, however, that, whilst on the one hand, the condition of the atmosphere in regard to Electricity has evidently a striking in- fluence on the rapidity of their growth (some plants having been known to increase in the most extraordinary manner during thundery weather), the electricity developed by the changes which take place in the economy of plants, has probably a very powerful influence on the condition of the atmosphere. It is well known that by all chemical changes, such as occur in every process of vegetation, from the absorption of the crude sap, to its final conversion into the substances which are to remain fixed or permanent through a long series of years, electricity is pro- duced. Further, the mere evaporation of water from the sur- face of the leaves will do the same ; and thus a constant series of changes in the electric state of plants will occur, which will communicate themselves to the atmosphere. 415. The general electric state of plants is found to be that termed negative ;* and if any circumstances cause the atmosphere to be positively electrified through a considerable space, some great commotion of the elements is not unlikely to take place. Hence, the dreadful hurricanes, which occasionally devastate the West Indian islands, may be in some degree accounted for. The evaporation of the water from the surface of the surrounding ocean, tends to make the air above it positively electrical ; and this, too, at the very time when the brilliant light and genial * Sec TREATISE ON ELECTRICITY. ATMOSPHERIC ELECTRICITY. MOTIONS OF PLANTS. 265 warmth of the sun, are causing the vegetation of the land to possess an opposite condition. " How wonderful," it has been remarked, " are the operations of nature ! The silent and peace- ful growth of a vegetation, whose splendour fascinates the eye, develops an agency, which, opposed to that produced by the rapid but unobserved evaporation from the surface of the sur- rounding ocean, tends to load the atmosphere with conflicting elements, from the depth of whose strife issues thunder proclaim- ing the approach of the hurricane and tornado." Of the Motions of Plants. 416. The gradual movements of the parts of plants, which occur as a part of the natural changes involved in their growth, such as the extension of their roots beneath the ground, and the elevation of their leaves and flowers by the upward growth of their stems and branches, have been already noticed; and the causes which influence th|m have been assigned, as far as our knowledge of them extends (. 107, 309). A curious experi- ment has been recently performed, which proves in a remarkable manner the influence of light, on the direction of the growth of these parts. Some seeds of Cabbages, Mustard, and Kidney- beans, were placed in Moss ; and were so arranged, that the only light they could receive was from a mirror, which threw the solar rays upon them from below, upwards ; the natural direction of their growth was in this manner completely changed, the stem being sent downwards, and the roots upwards. 417. We have here to notice, however, another set of move- ments displayed by Plants ; in which an evident change of place occurs, whilst they are being observed for a short time. One of these is known as the sleep of plants, from the circumstance of its generally occurring in the evening. This consists sometimes in the folding-together of the leaves, in other cases in their drooping, and occasionally in their clasping the stem ; it is most displayed in Leguminous plants having pinnate leaves (. 238.) ; and in them the lateral leaflets commonly fold together, whilst the leaf-stalks are bent downwards on the stem. Many flowers, also, exhibit a regular movement of the same description; 266 MOTIONS CAUSED BY LIGHT AND MOISTURE. closing together at night, and unfolding in the morning. There are a few species, however, which unfold at night and close during the day. There are some, too, which close during the day, when the sky is overcast and a storm is threatened. These changes seem almost entirely dependent upon the degree of light, to which the plant is exposed ; for they may be made to take place at the contrary periods, by keeping the plants in a dark- ened room during the day, and placing them at night in strong lamplight. It is usually some little time, however, before they become accustomed to the change ; and their movements are at first irregular. The mode in which light produces these move- ments has not yet been ascertained ; but it can scarcely be doubted, that it is by its influence on the exhalation of fluid from the soft tissues, on one side of the bending part more than on the other. Supposing that the part were otherwise bent, the influence of light upon the cells of the convex side would cause them to contract, and thus straighten it, a change which we shall presently see to be elsewhere effected by another cause acting in like manner. "Whilst, if the part were straight in the dark, so that the leaves were erect, and the flowers expanded, the influence of light, acting more on one side than on the other, would cause it to bend towards that side, by causing the tissue to contract. 418. The influence of water, or of varying degrees of mois- ture in the atmosphere, seems often to produce movements in the living plant, as well as in dead portions of its tissues. It is in this way that the closure and unclosure of the Rose of Jericho, and the Lycopodium of Peru, are occasioned, the one by drought, the other by the contact of fluid. This is easily ac- counted for, by supposing that the cells on one side are larger, and have thinner walls than those on the other ; and these will, therefore, be most easily distended when placed in water, and will soonest lose their fluid in drying. The beards of the Gera- nium and Wild Oat curl up in dry weather and straighten in damp ; those of some other plants perform the contrary move- ment. Such parts of plants are often used in the construction of hygrometers, to indicate the amount of dryness in the atmosphere, to detect dampness in beds, &c MOTIONS OF SEED-VESSELS. 267 419. Some of the most interesting among the vegetable movements are those concerned in the deposition of the seed. The Balsam termed Impatlens noli-me-tangere has a seed-vessel or capsule, formed of five divisions or valves ; which, when the seed is ripe, suddenly separate from one another and curl in- wards, scattering the seed to some distance. Now an examina- tion of the tissue of these valves shows, that their outer part consists of much larger cells than the inner, and that the fluid contained in it is the densest. By the laws of Endosmose (. 118), therefore, the fluids contained in the tissue of the interior will have a tendency to pass towards the outside, and will distend its vesicles still more. This distension of the out- side layer will manifestly give the valves a tendency to curl inwards ; just as when two thin plates of metal, which expand unequally by heat, are soldered together, and, heat being applied, the compound plate bends towards the side which expands least. This tendency continues to increase up to the time when the seed is ripe ; and it is then so powerful as to cause the separa- tion of the valves from each other, and to occasion the rolling inwards of each. Now it has been found that, if the valves be placed in a fluid more dense than that which the valves contain, such as syrup or gum-water, the fluid will be drawn off from their cells, according to the same law of Endosmose ; and the cells on the exterior will be emptied soonest, on account of 'their being larger and fuller than the others ; so that the valves be- come straight, and even curl outwards. But if they be put into water, the Endosmose, still taking place towards the side on which the fluid is densest, namely the interior of the cells, will distend them still more, and will cause the valves to curl inwards more powerfully than at first. Another instance of movement with the same object, which may be explained in a similar manner, is that of the seed-vessel of the common Squirt- ing- Cucumber (Momordica Elaterium). This, when ripe, very readily separates from its stalk ; and its pulpy contents are violently forced out from the aperture thus left. The pulpy matter surrounding the seeds occupies the centre of the fruit, and, by its own increase in amount, distends the cavity ; the 268 CONTRACTILITY OP VEGETABLE TISSUES. elasticity of the walls, therefore, occasions their violent con- traction, when an aperture is formed in any way, by which the distension is relieved. 420. Such explanations, however, will by no means account for all the evident movements of Plants ; and it is necessary to suppose their living tissues to be endowed with a property termed contractility, by which they are enabled to contract upon the application of a stimulus, just as do the muscular fibres of animals. The Vegetable kingdom affords many examples of this kind of contraction. Thus, if the leaves of the common Wild Lettuce be touched, when the plant is in flower, the part will be covered with milky juice, which is forced out through the stomata, by the contraction of the cells or vessels beneath. Again, in the flower of the Berberry, if the base of the stamen be touched with the point of a pin, the filament or stalk will bend over, so as to strike its top against the style or central pillar of the flower. This movement will hereafter be seen (. 437) to be connected with the process of fertilisation ; and it must be frequently caused by the contact of insects, which thus assist in that function. There is a curious New Holland plant, named Stylidium, sometimes cultivated in green-houses in this country, which has a tall column rising from the centre of its flower, and consisting of the stamens and style united ; this usually hangs down over one side of the flower ; but if it be touched ever so lightly, it starts up with a jerk, and rapidly swings over to the opposite side. 421. One of the most interesting of all the Vegetable move- ments, however, is that displayed by the Sensitive plant (Mimosa pudica). This is a Leguminous plant of the Acacia kind, which has its leaves very much subdivided into leaflets. When spread out in sunshine, they present no peculiarity of appearance ; but at night they fold together as in sleep, more completely perhaps than the leaves of any other plants. If, when expanded, one of the leaflets be slightly touched, it will close towards its fellow; the neighbouring leaflets will presently do the same ; the vein upon which these are set will bend downwards, and meet the one on the opposite side of the midrib ; the midrib itself will afterwards MOVEMENTS OP SENSITIVE PLANT. 269 bend down upon the stem ; and, if the plant he in a very irri- table condition (from its functions being in a state of great acti- vity), the other leaves are sometimes affected in a similar man- ner. The explanation of this very curious phenomenon requires, that the structure of the parts concerned in it should be explained. It is evident that the cause of the movement must be in some way propagated from the part touched, to the parts where the change actually takes place, namely the points where the leaflets join the veins, the veins come from the midrib, and the midrib from the stem. At every one of these points, there is a little swelling or intumescence, formed of very spongy cellular tissue, and con- taining a great deal of fluid in its cells. If the under side of the intumescence at the foot of the leaf-stalk be touched, its vesicles, being very irritable, contract and force out the fluid they contain; and this necessarily pulls down or depresses the leaf-stalk and all that it carries. If. on the other hand, anything distend the cells on the upper side of the intumescence, the leaf-stalk is pushed down, as it were, in a similar manner. The intumescence at the origin of each vein, and at the base of each leaflet, seems to possess the same properties, in a degree proportional to its size ; and they are all connected together, by the vessels and woody tubes of the midrib and veins. Now, when the tissue of any of the leaflets be touched, it appears to contract in the same manner as does that of the Wild Lettuce ; but instead of squeez- ing out its fluid upon the surface, it forces it through the vessels into the upper side of the intumescences at the base of itself and its fellow ; and these leaflets are thus caused to fold down and meet each other. The fluid forced out from the under side of their intumescences is probably carried to the upper side of those at a little distance ; and thus the neighbouring leaflets also are depressed. The depression of the veins upon the midrib, and of the midrib or footstalk itself upon the stem, will follow in like manner ; the extent to which the movement is propagated, being dependent on the amount of fluid expelled from the lower side of the intumescence, in the parts where it has already taken place. 422. Various other stimulants, besides the touch of a hard 270 SENSIBLE MOVEMENTS OF PLANTS. body, will produce similar effects. Thus, if electric sparks be communicated to the lower side of the intumescence, or the rays of the sun be concentrated on it with a burning-glass, a similar contraction of its vesicles, and depression of the leaf, will follow. In this, as in the foregoing instance, the leaves return after a time to their usual condition. Several species of the Acacia tribe, growing in warm climates, exhibit corresponding changes in a less degree. The closure of the fly-trap of the Dionaea (. 246.) may be probably explained on similar principles; the part here irritated, is the tissue at the base of the three thorns, on each side of the leaf; one of which must be touched, in order to excite the movement. CHAPTER XII. OF THE REPRODUCTION OF PLANTS. 423. THE limits which have been. set by the Creator, to the duration of the life of each being, that exists at any one time on the surface of the globe, would cause the earth to be speedily unpeopled, were not a compensation provided in the faculty of Reproduction, or the formation of a new being similar to itself, possessed by every kind of Plant and Animal. This power of creating (as it were) a living structure, with all its wondrous mechanism, possessed, too, in Animals of the faculties of sen- sation and thought, and in Man the residence of an immortal spirit, seems at first sight more extraordinary and mysterious, than any which we elsewhere witness. Yet it is not perhaps so in reality. The processes which are constantly taking place during the life of each being, and which are necessary to the maintenance of its own existence, are no less wonderful, and no less removed from anything which we witness in the world of dead matter. When the tree unfolds its leaves with the return- ing warmth of spring, there is as much to interest and astonish, in the beautiful structure and important uses of these parts, as there is in the expansion of its more gay and variegated blos- soms ; and when it puts forth new buds, which by their exten- sion prolong its branches over a part of the ground previously unshaded by its foliage, the process is in itself as wonderful, as the formation of the seed that is to propagate its race in some distant spot. Thus it is that scientific knowledge heightens our interest in Nature, by showing that, in those things which seem most common, there are as many sources of interest and instruc- tion, as in that which, from its apparently mysterious character, is usually regarded with more curiosity. 272 SIMPLEST MODES OF REPRODUCTION. 424. In the lowest plants, the process of reproduction is as simple as that of their growth. Each single cell of the Red Snow (. 48, Fig. 14) for example, produces within itself a num- ber of little particles ; which, at a certain period, are set free by the bursting of the parent-cell which incloses them. These granules then gradually enlarge, deriving their nourishment from the air and moisture around ; and in time they acquire the size of the parent plant, and in their turn produce a new family within themselves, which at the proper time they set free. A similar process takes place in the Yeast-Plant (. 56, Fig. 18). In the Confervas (. 41, Fig. 11), in which a number of cells are united together, end to end, in each filament, the several cells in like manner set free from their interior the little green particles, which serve to propagate their kind ; but the parent cells do not lose their own lives, in thus sending a new generation into the world ; for, instead of bursting, they allow the granules to pass out by a small aperture which forms in their walls. The growth of these particles within the parent cell may be distinctly traced : at first they are seen adhering to its inner wall ; then they separate themselves from it, and float in the fluid it con- tains ; then they are seen to move, while yet within the cell ; and after they have passed out, they continue their motion, even in an increased degree, for some time. At last they attach them- selves to some fixed object, and their development into new plants then begins. The particle gradually enlarges, and forms a cell containing fluid ; this cell takes an oval form, and a parti- tion then appears across it, dividing it into two ; one of these is elongated in the same manner, and is again subdivided ; so that at last, a complete filament, consisting of many cells, is produced ; this, in its turn, sends out reproductive particles from its cells, which go through the same processes. The curious movement of these granules (which any one possessing an ordinary micro- scope may observe for himself, by watching the reproductive processes in the common Confervas of our streams,) has given rise to the notion, that they were to be regarded as animalcules, at this stage of their existence ; a notion which is only mentioned here, to point out its absurdity ; since, whatever may be the cause of REPRODUCTION IN THE LOWEST PLANTS. 273 these movements (which is still obscure), they do not afford any evidence of being guided by Sensation and "Will, of which no real Animal can be entirely destitute. 425. In all these cases, the process of Reproduction is per- formed in a manner as simple as that, which any of the functions of Vegetable Life present to us. There is nothing more won- derful in the fact, that a cell should produce the rudiments or germs of new cells, in its interior, than that it should develope additional cells which are to form parts of its own structure, (as in the Yeast-plant, . 56, and higher plants in general,) from its outside. Each may be regarded as a Law of Nature ; which is only saying, that it is the mode in which the Creator operates. Now we shall find that, in higher plants, the essential part of the reproductive process is really the same following the same general laws ; and it is one of the most interesting results of scientific research, to see that things which appear widely dif- ferent, may often prove to be closely connected. We may hence learn a lesson, too, which is very useful in the ordinary concerns of life, not to judge too hastily by appearances. Nothing could seem more unlike, than the production of the seed of some noble tree, from the elegant flower, with all its complex apparatus of parts, and the propagation of the humble kinds of vegeta- tion we have been considering, by the simple contrivances just described. And yet it will be seen that, although in the former there is much of an additional character, subservient to particular purposes, yet the mode in which the germ is at first produced, is essentially the same. 426. The first stage of this increasing complexity, is seen in the higher Sea- weeds; in which, of the large number of cells that the whole plant contains, only a small part are appropriated to this function. Sometimes these reproductive cells are spread over the whole surface of their leaf-like expansion ; but some- times they are restricted to the extremities of the plant. In the common Bladder- wrack (Fucus vesiculosus, Fig. ]3), which abounds on most of the shores of Britain, a swelling may be seen at the end of each of its divisions, which is distinguished from the rest by its yellow colour, when the fructification which it 274 REPRODUCTION IN ALG.E, LICHENS, AND FUNGI. contains is mature. In this swelling, a number of pores or minute apertures may be distinguished ; and if the substance be cut across, it will be found that, beneath each of these pores, there lies a cell larger than the rest, and partly separated from it. This cell, when the fructification is ripe, passes out through the pore, and soon after bursts, setting free the minute particles it contains ; and these, like the granules of the Red Snow or of the Confervse, develope themselves into new cells ; by the multi- plication of which, a new plant similar to the parent is gradually reproduced. Now this cell, thrown off from the rest of the structure, and containing reproductive particles, which it after- wards sets free, corresponds with what in the higher Cryptogamia are called spores. These spores take the place of seeds, in this division of the Vegetable kingdom. "We shall hereafter (. 431, 440, &c.) trace the differences in their structure. 427. The processes of Reproduction in the Lichens and Fungi, appear to be as simple as those just described. Cells are seen in certain parts of the structure, which differ from those composing its own tissue, and which are destined to be cast forth from it, when the reproductive particles it contains are mature. The immense number of these reproductive cells or spores, which are contained in the different plants of the Fungus tribe, has been already noticed (. 50) ; and the various organs which con- tain them, will be hereafter described. One of the highest forms of this group, is the common Mushroom ; in which there is a very distinct separation of the fructifying, from the nutritive system. The spores are contained in a number of little tubes, which are arranged side by side in the membrane forming the cap of the Mushroom, and in the thin plates (commonly known as the gills), which spread from the centre on the under side of this ; whilst between this part and the roots, is a distinct stem. The whole energy of the Fungi seems directed towards the pro- pagation of their race ; and the duration of life in individuals is usually very transient. In Lichens, on the other hand, each indi- vidual frequently exists for many years, and its powers of pro- pagation are much inferior. Indeed some Lichens do not form any distinct spores ; but multiply themselves by little bud- like REPRODUCTION IN LIVERWORTS AND MOSSES. 275 bodies, which they form in hollows of their surface. In the common Cup-Moss, for example, (which is really a Lichen), these little bodies may be seen in the form of a fine greenish powder, in the hollows of the cups; and from these, when they are removed from the parent plant, new individuals will spring. 428. In the Liverworts we find a similar provision, as already noticed (. 32); but here there is a distinct set of organs of fructification raised above the general level of the plant, as shown in Fig. 5. The little bodies, forming as it were the spokes of the wheel, are cases containing spores or reproductive cells; and these are scattered, when mature, by a set of elastic spiral fila- ments which lie among them. When it begins to develope itself, the spore does not altogether burst and emit the granules it contains, as in the Algae ; but its outer coat only ruptures, and a long tube projects from its interior, within which new cells are seen to grow, taking their origin from the granules or minute germs, which the spore contained. These cells gradually increase into a leafy expansion, from the lower part of which root-fibres proceed ; and this in time acquires the appearance of the original plant, and forms its own organs of fructification. 429. The Drgans of fructification in the Mosses (. 27) are extremely beautiful and delicately formed ; the provision for the development and dispersion of spores, which in themselves resemble those of the Marchantia, being more complex than in the Liverworts. The little urns, mounted upon long stalks, which are peculiar to this group (. 27), are furnished with lids, that drop off when the spores within them are mature ; these spores having been developed around a central pillar termed the columella. Around the mouth of the urn is a very beautiful fringe, termed the peristome; the various forms of which aid the Botanist in distinguishing the genera and species of Mosses. This fringe is much influenced by moisture ; and its movements pro- bably aid in the dispersion of the spores. The subsequent changes which take place in the spore nearly correspond with those described in the last section ; the principal difference being, that a number of tubes are put forth instead of a single one. Each of these tubes can be perceived to contain some of the little T 2 276 REPRODUCTION IN FERNS. granules, which the cell produces within it ; and every one of these is capable of itself forming a perfect plant ; as has been ascertained, by cutting the tubes into several pieces. In general, however, all these go to form one young Moss, the cells which they produce uniting together at an early period ; and thus the process is rendered much shorter, than if the whole plant had to be developed from a single cell. 430. In the Ferns, again, we meet with another form of the same process. The spore- cases are here developed on the backs, or at the edges of the leaves, and differ in form from those of the Mosses ; but the spores which they contain, could not be distinguished from theirs. The thecee or spore-cases are usually nearly globular bodies, attached to the leaf by short stalks, as seen at >, Fig. 79. Although they are singly almost too minute to be distinguished by the unassisted eye, a number of them clustered together form the spots or ridges on the under side of the leaves, which are termed sori; these are shown at a. Each theca is sur- rounded by an elastic ring, which has a tendency to straighten itself; and when the spores are mature, the theca splits across, and the two halves are separated by the straightening of this ring (as seen at c), so as to allow the spores to escape. If a Fern-leaf, whose fructification has come to maturity (as may be known by the brownish tinge of the yellow or orange spots or ridges on its leaves), be placed with its under- side upon a piece of white paper, this will be found in a day or two covered with a very fine brown dust. These are the spores which are scattered by the bursting of their cases. The process of development of these spores presents several points of interest. In its first stages it closely resembles that of the Marchantia. The outer coat of the spore ruptures, and the inner one projects into a long tube; within which, as well as within the original cavity, new cells are formed from the germs included within it. The first tendency of these newly-formed cells is to grow together, TRANSITORY CONDITIONS OF LIVING BEINGS. 277 and to increase into a leaf-like expansion, very much resembling that of the Marchantia. In the middle of this (which has received the name of primary frond), a knot or protuberance gradually makes its appearance; and this is afterwards pro- longed above into a sort of stem, and below into a root. From this stem, the true leaves or fronds are afterwards developed, unrolling themselves after the manner formerly described (. 25); and, when these make their appearance, the primary frond decays away, leaving no traces of its existence. In this very curious process, we see that the Fern passes, as it were, through the stage which is permanent in the Marchantia ; but that when it attains a higher form, the organ, which was only for a time subservient to its existence, decays away. 431. Many instances of a similar kind present themselves in the Animal kingdom. Thus the Frog comes forth from the egg in a state resembling that of a Fish, breathing by gills instead of by lungs, possessing a long tail by which it moves itself in the water, and destitute of legs. Subsequently legs are produced, which render its tail unnecessary ; and lungs are developed, which perform its respiration more effectually than gills ; and the first two sets of organs, though they permanently exist in Fishes, disappear in the Frogs, as soon as they have served their temporary purpose. Corresponding changes, hardly less striking than this, take place during the development of every one of the higher Animals ; and in every instance we see that, when a higher form is attained, the parts which had their uses in an inferior condition of existence, are cast off as cumbrous and unnecessary. How beautifully does this principle apply to the history of the development of the Human soul ! At first it is entirely dependent for its activity, on the impressions which it receives through the bodily frame, with which it is connected. The calls of hunger, the presence of unaccustomed objects, strong impressions upon its senses, first excite its attention ; and all its subsequent acquisition of knowledge, depends upon similar in- fluences. Perfect in their kind as are the organs of sensation, by which these impressions are communicated, there are still bounds to their operation. All that their highest exercise, with the aids derived from the most refined ingenuity, can effect in this life, 278 REPRODUCTION IN FLOWERING PLANTS. serves but to give to the philosophic mind a glimpse of the won- ders of Creation ; and there can scarcely be to such a mind a more powerful natural* argument in favour of a future state, than that which rests upon the vast amount of knowledge, of which the sources are presented to Man, and the insatiable desire for it which he possesses, compared with his very limited power of satisfying that desire, within the short duration of an ordinary life. All analogy, then, leads to the conclusion, that with the mortal body, the soul shall cast away those instruments, which are adapted only to the present material finite state of existence, and shall be endowed with more direct means of becoming acquainted with those glorious truths, which here it only sees " as through a glass, darkly." 432. To return from this digression. In reviewing the pro- cesses of Reproduction in Cryptogamia, we perceive that they are everywhere essentially the same. The spore, or reproduc- ti re cell, contains a number of granules, each of which is capable of producing a new cell, at the expense of the fluid which its parent contains ; and these new cells are able, either together or separately, to develope themselves into plants similar to their parents, without any other influences, than those which they receive from the light, air, and moisture, which surround them. In the lowest cryptogamia, we have seen that these granules are thrown at once, as it were, upon their own resources ; being set free by the parent-cell before their development into new cells has commenced. But in the higher, we have observed that they remain within the parent cell, which seems to elaborate or pre- pare their nourishment. Now we shall find that the real essen- tial difference between the Phanerogamic and the Cryptogamic (the flowering and the flowerless) plant, consists in this, that the former possesses a series of organs fitted to receive and che- rish the germ, and to assist in its early development, of which the latter is destitute ; and that the presence or absence of those parts, which are ordinarily known as constituting the flower, is of no primary importance. These parts are often absent, with- out the process of Reproduction being thereby affected ; and, on * By this is meant an argument drawn from the Natural World, as distinct ftom the Revealed Word of God. ANTHERS AND POLLEN-GRAINS. 279 the other hand, there are many flowers, which appear perfect to the uninstructed eye, but which are totally destitute of fertility. 433. The parts of a flower essentially concerned in the repro- ductive process are the stamens and pistil. The stamens are little bodies, having yellow heads mounted on long stalks, which are seen around but not in the centre of the flower. These stalks are called filaments ; whilst the heads are called the anthers. Each head is usually seen to be more or less com- pletely divided into two parts, which are termed anther-lobes. These are commonly united together; as in Fig. 80, a, duced a number of minute yellow bodies, usually of a globular form, which together constitute the fine dust, known as the pollen or farina of the flower. Each grain of pollen, when exa- mined with the microscope, is seen to consist of a cell, exactly analogous to that which constitutes a spore. It has two or more coats, which enclose a fluid; and in this, a large number of extremely minute granules may be seen with a good microscope. These granules are probably the germs of new cells ; being ana- logous to those which are sent forth from the Red Snow, the Confervas, and the Yeast Fungi. They may be seen to move within the parent cell, or pollen-grain, previously to the time when its walls become too thick to allow of their being observed through them ; and, when the contents of the pollen-grain are mixed with water, they are seen to be constantly performing a sort of vibratory motion. The anthers, or receptacles of pollen, which evidently correspond with the capsules or spore-cases of the Cryptogamia, burst when their contents are mature, and scatter the grains forth. They have various ways of opening ; sometimes they split along their length as at a, Fig. 80 ; some- times transversely, as at b ; sometimes by little openings at their 280 STRUCTURE OP OVARIUM, PISTIL, ETC. extremity, termed pores, as at c ; and sometimes by valves, as at d. These different methods are characteristic of different tribes of Flowering plants. 434. Now the portion of the reproductive system in the Phanerogamia, to which nothing analogous exists in the lower tribes, is that which is denominated the ovarium or seed-vessel ; this occupies the centre of the flower, being sometimes situated above, and sometimes apparently below, the point at which the leafy parts of the flower arise from the axis which bears them. This ovarium is the part, in which are formed the ovules or young seeds ; and these, after being fertilised in the manner presently to be described, ripen into the perfect seeds. Some- times it consists of several evident divisions ; in other instances, these are united together, more or less closely ; and all mark of a division may even disappear. The ad- joining figure represents the centre of a flower, in which the several parts of the ovarium remain separated ; three only are seen, the others being con- cealed by them. These separate parts are termed carpels. Each carpel is surmounted by a sort of pillar, termed the style; which usually expands at its summit, into a fleshy surface called the stigma. When the carpels adhere closely together, their styles also fre- quently unite, so as to form a single pillar ; which sometimes, however, di- vides again into several branches at the top. The ovarium, with its style and stigma, is then called the pistil; and sometimes each separate carpel, with its own style and stigma, receives the same appel- lation. An excellent illustration of an ovarium consisting of many carpels, appearing externally single, but each really sepa- rate from the rest, is the Orange ; the juicy part of which fruit is the ovarium, composed of a number of carpels adhering to- gether, but not so closely united as to prevent their being torn FIG. 81. PISTIL OF CORIARIA MYRTIFOLIA, showing distinct carpels and styles. STRUCTURE OP OVARIUM AND FLOWER. 281 apart. The position of the pips or seeds of the Orange, will give a good idea of the manner in which they are usually situated within the carpels, especially when they are few in number. Sometimes, ho we ver, they are attached to the whole length of the carpel, from one end to the other, as is seen in the common Pea, of which each pod is a separate carpel. The portion of the carpel from which the ovules arise, is usually thick and fleshy, and is termed the placenta. The section of the pistil of the Whortleberry -, (Fig. 82) will give an idea of the arrangement of the parts in an ovarium, whose carpels and styles have united. The ovarium , of this flower is wrapped over by the leafy portion of the flower itself; which is seen to rise beyond it at b. The centre of the ovarium is occupied by a thick fleshy placenta, formed by the union of that of the several carpels ; and on this the ovules are clustered. Above is seen the signal style PIG. 82. PISTIL OF VAC- with its stigma. Another variety of the M j same kind of structure, is shown in Fig. 83 ; centa ; e, ovules;'/, pistil; i i 7 1*1 &n of which that of the Pansy Or Heartsease, Fig. 84, may be taken as an example : in this, the partitions have disappeared ; but the placenta? of the several carpels, instead of remaining clustered PIG. 83.-OVARIUM OP THAMNKA UNI- FLORA; a, calyx; b, ovarium ; c, disk; d, 282 FERTILIZATION OF THE OVULES. together, are attached separately to the walls of the ovarium as at a. 435. These two sets of organs are by no means constantly united, how- ever, in the same flower. The stand- * ., . niferous or stamen-bearing flowers, are frequently distinct from those which are pistilliferous or bear pistils. When they occur on some other part of the same Fl - 84 OVARIUM OK VIOLA TRICOLOR ; a, placenta. plant, it is said to be monoecious (single- housed); if on a different plant, it is dioecious (or double-housed). Sometimes the same collection of flowers contains some perfect ones, with others staminiferous, and others pistilliferous only. There is reason to believe that, when either set of organs is not developed, the rudiments of it really exist ; for these parts are frequently made to appear by cultivation. 436. If the ovarium be cut into, previously to the opening of the flower, it will usually be found to contain a great number of the ovules or young seeds. These are at that period quite soft ; and their interior is filled up with a kind of pulp, which is enclosed in two or more envelopes. These seed-coats do not entirely cover the central envelope, but leave a small opening, which is called the foramen. This opening may be easily detected in the perfect seed (although it has there nearly closed up), by soaking it in water, and then pressing out the fluid that has been absorbed, which will be seen to issue from this little orifice. The foramen, as will presently appear, has a very important purpose in the fertilization of the seed; which, at the period now described, contains no trace of the germ of the new plant. 437. This germ appears to be conveyed into it from the pollen, in the following curious manner. The little grains or cells, when set free from the anthers, fall upon the stigma of the pistil. In general the anthers are situated above the stigma, the stamens being longer than the pistil in flowers that are erect or upright, and shorter in those which hang down ; but some- times a special provision is necessary, for the conveyance of the pollen to the stigma, especially in monoecious or dioecious plants. FERTILIZATION OF THE OVULES. 283 This function is often accomplished by Insects ; which, in going from flower to flower in search of honey, cover over their bodies with pollen-dust, and rub them accidentally against the pistils of other flowers. When the pollen falls on the stigma, it is caused to adhere to it by a honey-like secretion from its surface ; and after a short time, it undergoes a remarkable change, which closely resembles that already described in the spore of the Cryptogamia. 438. The outer coat of the pollen-cell appears to burst at one or two points, and to allow the inner coat to pass out through it in the form of a tube. This tube insinuates itself between the cells of the stigma, and passes down between the long and loosely-arranged cells of the style. It gradually extends, until FIG. 86. POLLEN-GRAIN, OF (ENO- THERA BIKNNIS, sending its tubes a, a, between the cells, 6, of the stigma. it reaches the ovarium itself, even when the style is several inches long. The pollen-grains are not always globular, but are some- times triangular, and emit a pol- len-tube at each corner, as in Fig. 86 ; such are analogous to the spores of Mosses, which put forth several tubes. The tubes, when they arrive at the ovarium, direct themselves towards its different chambers, and have been seen to enter the apertures in the several ovules ; which are at that time directed towards the part of the base of the style, from FIG. 85. SUCTION OF THB TOP OF THE STYLE OF SNAP- DRAGON ; showing the pas- sage of the pollen-tubes between its cells. 284 EARLY DEVELOPMENT OF THE EMBRYO. which the pollen-tubes project themselves. Sometimes a consi derable change in the position of the ovule is necessary, in order that the foramen should be applied to the right portion of the wall of the ovary ; but this change always takes place, just as the pollen-tubes are passing down the style. The granules which the pollen-grain originally contained, are seen to pass down the tube ; and some of them are conveyed by it, into each ovule. Whilst yet within the tube, they are seen to develope themselves into new cells ; and these cells form the rudiment of the future plant. 439. The germs are thus conveyed into a sort of receptacle, where they are supplied with nourishment, that has been pre- viously prepared and stored up for their use by the parent structure; and they are thus greatly assisted in their early development. The pulpy matter contained in the ovules, con- sists of starch and sugar; and these nutritious substances are absorbed by the cells of the embryo, which increase at their expense. The first increase of these cells does not so much tend, however, to form those parts which are afterwards to be developed into the stem, root, and leaves ; as to produce those temporary structures, termed cotyledons or seed-leaves (. 21), which are destined, like the primary frond of the Ferns, to assist for a time in the development of the permanent structure, and then to wither and decay. Hence, at the time of the ripening of the seed, the cotyledon (which is sometimes double, sometimes single see . 440 2) forms the greatest part of the embryo or young plant. Besides this, the seed contains a considerable quantity of starch, destined for the nourishment of the young plant, when it is beginning to sprout, and whilst yet unable to take in food for itself. This starch is sometimes absorbed into the tissue of the cotyledons, rendering them thick and fleshy, as in the Pea or Bean ; and then these, with the small germ to which they belong, form the entire contents of the seed. In other instances, how- ever, the cotyledons are thin leafy organs, and occupy, with the germ, but a small part of the seed ; the remainder then consists of a separate store, which closely resembles the yolk-bag of the eo-or, and is termed the albumen. This is the case in the seeds eo' DICOTYLEDONOUS SEED.- GERMINATION. 285 FIG. 87. SEED OF THE BEAN, of all Monocotyledonous plants ; and also in some Dicotyledons, as the Ash and Horse-chesnut. 440. The structure of the seed . of the two principal divisions of the Phanerogamia, is shown in the adjoining figures. In Fig. 87, is seen that of the Bean, a Dicotyledon, after the seed- coats have been stripped off, and the cotyledons separated. The two large fleshy lobes, a, #, are the cotyledons, into which the whole of the starch, originally contained in the ovule, has with "* cotyledons ; a, a, sepa- * ' rated ; b, germ. been absorbed. Between these is the real germ ; the upper extremity of which, termed the plumula, subsequently developes itself into the stem, and puts forth leaves ; whilst the lower part, which is always c directed towards the foramen, becomes the root. The plumula sometimes presents the appearance of the plant in miniature; its leaves and buds being quite discernible, though on a very small scale. The subsequent development of the germ contained in the seed into the perfect plant, is that which in its early stage is known as germination. Of the causes which excite it, we shall presently speak. When a seed like that of the Bean begins to germinate, it first swells and bursts its seed-coats ; the plumula then extends upwards, bringing the cotyledons just above the surface of the ground ; whilst the radicle penetrates it in the opposite direc- tion. In some plants, however, the cotyledons FIG. 88. remain underground, as in the Oak ; and GERMINATION OF DICO- there are a few, in which they are entirely TYLEBONOUS SEED \ Cl, ' piumuia; 6, radicle; absent. The cotyledons, when exposed to c,c, cotyledons, the light, become green, and perform for a time (though imperfectly) the functions of leaves ; at the same 286 STRUCTURE OF THE SEED. time, yielding to the young plant the nourishment they contain. By the time this is exhausted, the true leaves and roots are suffi- ciently developed, for the support of the structure; and the coty- ledons, being then no longer required, decay away. Thus it is seen that, in all the essential points, the history of the young Phanero- gamic plant corresponds exactly with that of the young Fern ; the chief difference consisting in this ; that the development of the former, up to the time when its cotyledon or primary frond ceased to support it, is assisted by the nourishment prepared for it by the parent ; whilst the latter has no such assistance, but obtains its nourishment from the surrounding air and moisture. 441. The adjoining repre- sentation of the seed of the Marvel of Peru, affords an example of a dicotyledonous seed, possessing leafy cotyle- dons, and a separate albumen ; in these, the process of germi- nation is the same, except that the cotyledons only perform the functions of temporary leaves, the nutritious part of the seed being retained withm its coats, until it is exhausted by the young plant. 442. In the seeds of the Monocotyledons, the structure of which is illustrated by the accompanying figure of that of the Onion or Lily, the albumen is always separate ; and the embryo, which occu- pies but a small proportion of the whole mass, cannot always be readily distinguished in the midst of it, until germination commences. The cotyledon at first completely sheathes the plumula, which afterwards pierces it, and unrolls its first true leaf. 443. Now it is an interesting fact, that the division of the FIG. 89.-SKED OK THE MARVEL OF PERU. FIG. 90. SECTIONS OF SEED OF ONION. a, a, albumen ; b, b, embryo. CONDITIONS OF GERMINATION. 287 Phanerogamia founded upon the structure of the seed, exactly corresponds with that formed according to the structure of the stem ; that is, all Exogens are Dicotyledonous (with only a few apparent exceptions) ; and all Endogens are Monocotyledonous. Moreover, all the Acrogens, which have no regular method of adding to the diameter of their stem, are destitute of the power of forming true seeds ; the germs being, as it were, at once cast upon the world, instead of being reared and cherished by parental care. It has formerly been pointed out, that Exogens, Endo- gens, and Acrogens, differ also in the distribution of the veins in their leaves (. 229 32) ; and it may here be mentioned, that they differ also in the number of parts of which the flower is usually composed. Thus, in Exogens, the regular number of stamens is either four or five, or a multiple of one of these num- bers ; and that of the carpels is similar : whilst in Endogens, the number of the same parts is three, or a multiple of it. The number of the external or leafy parts of the flower follows the same laws, as will be hereafter explained. 444. The conditions requisite for the germination of the seed, are warmth, moisture, and the presence of oxygen. The process is also favoured by darkness. The influence of each of these agents will be readily understood. No vital action can go on without a certain amount of heat ; and, where this is not produced within the being, it must be derived from without. The germination of the seed is as much dependent upon warmth, therefore, as the hatching of the egg of a bird ; though the amount it requires is not nearly so great. Moisture is also evi- dently required, for the conversion, into a fluid state, of the dry nutriment, which has been previously stored up in the seed ; and no change can commence, until this be supplied. The pre- sence of oxygen is necessary, because the conversion of starch into sugar requires (as formerly stated, . 283) that some of the carbon of the former should be set free ; and this can only be accomplished, by the union of it with oxygen, so as to form car- bonic acid. This process is favoured by darkness, because light has a tendency to produce the contrary change i\\e fixation of the carbon within the structure (. 286). 288 CONDITIONS OF GERMINATION. 445. It is interesting to observe how all these conditions are supplied, in the ordinary course of Nature, by the soil in which the seed is dropped. If it be sown during the spring or summer, it speedily begins to germinate ; but if it is deposited in the autumn, it remains almost unchanged, until the winter has passed, and the returning warmth of the air and earth arouses it into activity. It is seldom that the soil is so completely destitute of moisture, for any long time together, as not to be able to excite seeds to germinate ; but their sprouting is well known to be favoured by damp weather ; and if seeds, through being put into the ground during a drought, remain undeveloped, they are brought forwards very rapidly by a genial shower. A porous soil is to be preferred, on account of the free admission of air, which it gives to a germinating seed ; as well as for the other processes of vegetation (. 178, 9). A stiff clay soil pre- vents this necessary contact ; and thus impedes germination. So complete a check, indeed, may be thus produced, that it has been proposed to bury seeds in clay rammed hard, when it is desired to convey them from one part of the world to another, through very hot climates ; the high temperature of which might destroy their vitality, if its influence were not partly pre- vented, by the bad-conducting power of the mass, in which they are thus enclosed. If seeds be buried very deep, even in a light soil, the contact of oxygen will be sufficiently impeded to pre- vent their germination ; and the bringing such seeds nearer to the surface, will then have as much influence in causing them to sprout, as the supply of either of the agents just mentioned, which might have been previously deficient. 446. The seeds of most Plants are endowed with a remark- able power of preserving their vitality, for an almost unlimited time ; if they are placed in circumstances, which neither call their properties into active exercise, nor occasion the decay of their structure. The conditions most favourable for this preser- vation, will evidently be, a low or moderate temperature, dry- ness of the surrounding medium, and the absence of oxygen. If all these be supplied in the most favourable manner, there seems no limit to the period, during which seeds may retain their vita- PROLONGED VITALITY OF SEEDS. 289 lity, that is, their power of performing their vital operations, when placed in the proper circumstances. And even if moisture or oxygen be not entirely excluded, the same effect may result, provided that the temperature be low and uniform. Thus the seeds of most plants may be kept for several years, freely ex- posed to the air ; provided they are not exposed to dampness, which will cause them either to germinate, or to decay. Some of those, which had been kept in seed-vessels of plants preserved in the herbarium of Tournefort, a French botanist, were found to retain their fertility, after the lapse of nearly a century. 447. Instances are of no unfrequent occurrence, in which ground, that has been turned up, spontaneously produces plants different from any in their neighbourhood. There is no doubt that, in some of these cases, the seed is conveyed by the wind, and becomes developed only in spots, which afford it congenial soil ; as was formerly mentioned in regard to the spores of the Fungi (. 50). Thus, it is commonly observed, that clover is ready to spring up on soils, which have been rendered alkaline by the strewing of wood-ashes, or the burning of weeds, or which have had the surface broken and mixed with lime. But there are many authentic facts, which can only be explained upon the supposition, that the seeds of the newly-appearing plants have lain for a long period imbedded in the soil, at such a dis- tance from the surface, as to prevent the access of air and mois- ture ; and that, retaining their vitality under these conditions, they have been excited to germination by exposure to the atmo- sphere. The following possesses considerable interest. 448. To the westward of Stirling, there is a large peat-bog, a great part of which has been flooded away, by raising water from the river Teith, and discharging it into the Forth ; the object of this process being, to lay bare the under-soil of clay, which is then cultivated. The clergyman of the parish was on one occasion standing by, while the workmen were forming a ditch in this clay, in a part which had been covered with four- teen feet of peat earth ; observing some seeds in the clay, which was thrown out of this ditch, he took them up and sowed them ; they germinated, and produced a species of Chrysanthemum. 290 PROLONGED VITALITY OF SEEDS. A very long period of years must have probably elapsed, whilst the seeds were getting their covering of clay ; and of the time necessary to produce 14 feet of peat-earth above this, it is scarcely possible to form an idea ; but it must have been (in the natural course of things) extremely great. 449. The following circumstance, which occurred about 30 years ago in the State of Maine, in North America, is, perhaps, still more remarkable. Some well-diggers, when sinking a well, at the distance of about 40 miles from the sea, struck, at the depth of about 20 feet, a layer of sand ; this strongly excited curiosity and interest, from the circumstance that no similar sand was to be found anywhere in the neighbourhood, or anywhere nearer than the sea-beach. As it was drawn up from the well, it was placed in a pile by itself ; an unwillingness having been felt to mix it with the stones and gravel, which were also drawn up. But when the work was about to be finished, and the pile of stones and gravel to be removed, it was found necessary to remove also the sand-heap. This, therefore, was scattered about the spot, on which it had been formed ; and was for some time scarcely remembered. In a year or two, however, it was perceived that a great number of small trees had sprung from the ground, over which the sand had been strewn. These trees became, in their turn, objects of strong interest ; and care was taken that no injury should come to them. At length it was ascertained that they were Beach-Plumb trees ; and they actu- ally bore the Beach-Plumb, which had never before been seen, except immediately upon the sea-shore. These trees must, therefore, have sprung up from seeds, which had existed in the stratum of sea-sand pierced by the well-diggers ; and, until this was dispersed, in such a manner as to expose them to the air, they remained inactive. " By what convulsion of the elements," adds the narrator, " they had been thrown there, or how long they and quietly slept beneath the surface of the earth, must be determined by those who know very much more than I do." 450. The following is an example of the same general fact, which is interesting from its connexion with historical events. In the year 1 71 5, during the rebellion in Scotland, a camp was PROLONGED VITALITY OF SEEDS. 291 formed in the King's Park (a piece of ground belonging to the castle) at Stirling. Wherever the ground was broken, broom sprang up, although none had ever been known to grow there. The plant was subsequently destroyed ; but in 1 745, a similar growth appeared, after the ground had been again broken up for a like purpose. Some time afterwards, the Park was ploughed up, and the broom became generally spread over it. The same thing happened in a field in the neighbourhood, from the whole surface of which about nine inches of soil "had been removed, The broom-seeds could not have been conveyed by the wind, although the plant is a common one in the neighbourhood, because they are heavy and without wings (. 471) ; and the form of the ground is such, that no stream of water could have transported them, or have covered them afterwards with soil. Such an effect must have resulted from the operation of causes, continued through a long period of time. 451. Perhaps the most remarkable instance on record, as presenting satisfactory proof of the lapse of at least 1600 or 1700 years, is one related by Dr. Lindley. "I have now before me," he says, " three plants of Raspberries, which have been raised in the gardens of the Horticultural Society, from seeds taken from the stomach of a man, whose skeleton was found 30 feet below the surface of the earth, at the bottom of a barrow,* which was opened near Dorchester. He had been buried with some coins of the Emperor Hadrian." Corn-grains enclosed in the bandages which envelope the mummies, are said to have occasionally germinated, though most of them seem to have lost their vitality. There is nothing improbable in the fact ; but as the Arabs, from whom the mummies are commonly obtained, are in the habit of previously unrolling them in search of coins, &c., it is not always certain that the seeds which have sprouted were really at first enclosed with the mummies. * These barrows, as they are termed, are large mounds of earth, which are very common on the downs along the south coast of England. They are evidently artificial, not natural ; and, when dug into, are usually found to contain human remains, with pottery ; weapons, &c. Hence they are evidently burial-places ; and as a large number of them are generally found together, they seem to have been erected on fields of battle, to contain the bodies of the slain. u 2 292 HYBRID PLANTS. 452. When a plant is raised from seed, it will always bear a strong likeness to its parent ; and if the species be one which lias little tendency to variation, it will resemble it very closely. But there are many species, which have a great disposition to present deviations, from what may be considered their original form (. 13 16); and thus, from the seeds of the same parent, it is often possible to produce, by a difference of treatment, a number of plants differing considerably from one another. What- ever such differences may be, however, these plants are all re- garded as belonging to the same species, since they are descended from a common stock ; and by such experiments, it may be often shown that plants, which have been considered as distinct species, have no real title to be so classed (. 16). 453. It is often possible, however, to produce seeds capable of giving origin to plants, that shall combine the characters of two different races. This is done, by placing the pollen of one species upon the stigma of another ; so that the germ, furnished by one, shall be nursed (as it were) by the other. It is not difficult to understand, how the germ thus influenced, should be subsequently developed into a form, differing from that of its own parent ; for the germs of Cryptogamia, which are not re- ceived into any ovule, but are dependent upon the elements alone for their support, are often developed (especially among the lower tribes) into forms very different from that which they would naturally present. Thus a Mucor, a sort of Fungus con- cerned in the production of mouldiness, has been seen growing in water, in a form so like that of a Conferva, that it was only recognised as a Fungus, when it lifted up its fructification above the fluid. 454. The plant developed from a seed produced by the agency of two races, is termed a hybrid. It is necessary, in order that the seeds thus formed should be fertile, that the parent species should be nearly allied to each other ; and it is very seldom that a hybrid can be produced, when they do not belong to the same genus. Now, if the hybrid bear flowers, and its stigma be fer- tilised with its own pollen, it may produce seeds that can be raised into plants like itself; and these may flower and produce LIMITS OF HYBRIDITY. STRUCTURE OP FLOWER. 293 a third generation in like manner. But there is no instance in which a hybrid race, which has thus originated in the intermix- ture of two species really distinct, has ever been continued without intermixture, beyond the fourth or fifth generation. The plant, when not fertile by itself, may bear seed, if its stigma be .sprinkled with the pollen of one of its parent species ; and its pollen may be fertile, when placed on the stigma of either of these. In this manner, a race intermediate between the hybrid and one of the parent species is produced ; and this is continued longer, just in proportion as it is caused to approach the pure breed, by a successive intermixture of this kind. The end of all hybrid races, produced between species really distinct, appears to be, therefore, that either the race becomes soon extinct, which it will do if kept separate, or it merges into one of the parent races, if continued by intermixture with either of them. This principle affords a valuable test for determining what really are, and what are not, distinct species ; for if a hybrid race can be produced between them, which continues to be fertile of itself, the probability is strong, that they are only varieties. Cultivators of flowers are constantly in the habit of producing such new races, between the different varieties of many plants, for instance, the South American Amaryllis and the Calceolaria; both these species are very much disposed to spontaneous varia- tion; and, by selecting the most beautiful of the new races, which spontaneously originate from their seeds, and causing these to produce hybrids, a still larger amount of variety, both in form and colour, may be obtained. These hybrids are of equal fertility with their parents, since the latter are not separated by any really essential difference. 455. Having now considered the general structure and offices of those organs of Phanerogamia, which are most interesting to the Physiologist, from their connection with the important func- tion of Reproduction, we shall notice those parts of the flower which are less essential to this object, but which commonly excite 294 CALYX AND COROLLA. more interest, on account of the varied and beautiful forms and colours they present ; namely, its external leafy portion. This may be altogether termed the perianth^ or floral envelope ; the essential portion of the flower being, as before explained, the stamens and pistil that occupy its centre, which are sometimes destitute of any protection. The perianth may be regarded as consisting, in its most regular form, of two circles (arranged like the whorls or verticils of leaves) of leafy organs ; of which the outer circle is generally green, and the inner one coloured.* Of this outer circle, the leaves or sepals not unfrequently grow together, or adhere, at their edges; so that a sort of cup is formed; hence the whole is termed the calyx (cup). The inner whorl is termed the corolla, and its divisions are called petals; they not unfrequently grow together in the same manner (as in the Campanula or Harebell) forming a second cup within the calyx. 456. When the Calyx seems formed of but one piece, in con- sequence of the adhesion of its leafy portions, it is said to be monosepalous (possessing but a single sepal) ; and when the petals have united in a similar manner, the corolla is said to be mono- peialous.\ Though these terms are not strictly correct (since there are really as many sepals and petals in the one case as in the other), they are convenient, and are often employed in describing plants. The terms yamosepalous and gamopetalous have been introduced to designate these forms of calyx and corolla ; their signification being, that the sepals and petals are united or married at their edges. The real nature of such a calyx or corolla is shown by varieties, or monstrosities, like that deli- neated in the adjoining figure; here the regular form of a * In Botanical language, the term coloured always means, that the part is not green ; green being regarded as no colour in Plants. A white flower is spoken of as coloured. f It is worthy of inquiry, whether it would not be more proper to consider the monosepalous calyx and the mouopetalous corolla (and even many of those in which the sepals and petals are distinct), as consisting of so many leaflets^ or parts of a single leaf; in the some manner as, according to a suggestion formerly made (. 303, note), some verticils probably consist not of a number of leaves, but of a single one, divided into leaflets. CALYX AND COROLLA. oorolla; * - monopetalous corolla, (in which the petals have grown together to form a tube, and are only separate at the top) is shown at a; whilst b shows the separate condition of the petals, which is occa- sionally seen as the conse- quence of a want of adhesion between their edges. Dif- ferent kinds of flowers, too, exhibit every variety, between the completely-separate and the completely-adherent condition of the sepals and petals ; and these differences are often very useful, in distinguishing them from each other. 457. Outside the calyx, is not unfrequently to be found another whorl of leafy bodies, more resembling in their aspet the ordinary leaves of the plant ; these are called bracts, arid are well seen in the Strawberry, where they surround and alternate with the sepals of the calyx. When no complete circle of them is seen, one or two are often present, and then they are generally larger. They do not always immediately surround the flower,; but are often to be found at the bottom of the flower-stalk. In Fig. 92 are shown the Bracts, as they occur in the lame and Hellebore ; in the former case (#) we see the base of the flower -stalk sheathedby a single leaf, which closely resembles the ordi- nary leaf of the plant; in the latter (b) t we see the flower itself enclosed in similar leaves. In Fig. 93 the bracts of two umbelliferous * plants are represented ; these * By Umbelliferous plants is meant that tribe, in which the flower-stalks FIG. 92. 296 BRACTS, INVOLUCRE, SPATHE. commonly form a whorl of three or more leaflets, where the flower-stem first divides; and other smaller whorls are seen, FIG. 93. INVOLUCRE: OF A PHLOX AND CHINESE PRIMROSE. where the second subdivisions take place. Such whorls are usually termed involucres. Where a single large bract encloses the flower-stalk and bud before its expansion, this is usually termed a spathe. This is seen in the Snow- drop, Onion, Narcissus, &e. The Spathe is peculiarly large in the Palms, where it often has to enclose a large branch loaded with flowers. It is of great size also in the Arum, enclosing tho central pillar termed the spadix, on which the flowers are clus- tered ; in the common Wake-robin (or Lords and Ladies) of our hedges, this FIG. 94. SPATHE OF NARCISSUS AND ARCM. ' , spathe is green ; but in divide and subdivide in such a manner as to produce the peculiar form termed an umbel, which is seen in the Hemlock, Carrot, Parsley, &c. BRACTS. ANALOGY OP SEPALS AND LEAVES. '297 some exotic species, cultivated in our drawing-rooms, it is white, arid is commonly regarded as the flower. These bracts may be regarded, as establishing the transition of form and structure, between the common leaves of the plant, and those modified or metamorphosed leaves, which form the perianth. Sometimes they can scarcely be distinguished from the former; whilst in other cases, they are brightly coloured, and more closely resemble the latter ; and, in the Hydrangea and some other plants, they really constitute the most showy portion of the flower; being very large and brilliant, whilst the flower they enclose is so small, as to be almost overlooked. In many instances, the bracts form so gradual a transition, between the true leaves and the parts of the flower, that it is very difficult to say where the former end and the latter begins. This is the case in the double Paeony, a plant now very common in gardens. Its lower leaves are very complex in their structure, being divided into a great number of segments (. 235) ; in tracing them up the stem, they are found to become simpler and simpler in their character as they approach the flower, and also to diminish in size ; and at the same time, their spiral arrangement round the stem becomes more evident, the intervals between them being diminished. In this manner, they may be at last traced into the outermost whorl of the leafy parts composing the flower ; and it is quite impossible to specify the exact place, at which the true leaves may be said to end, or the calyx to commence. 458. From this it would appear, that there is no essential difference between the sepals of the calyx and regular leaves ; and examination of their structure bears out the conclusion. If we take an example from a plant, in which the sepals are distinct from each other, and green, we should find it difficult to assign any important characters, in which they differ from leaves. They possess two layers of cuticle, furnished with stomata; having green cellular tissue or parenchyma between them, supported by veins consisting of woody fibre and vessels. There are many cases, however, in which the calyx is brightly coloured, equalling the corolla in beauty, and even surpassing it in brilliancy. In the Lilies and Tulips, we find the perianth composed of six 298 ANALOGY OF SEPALS AND PETALS. coloured parts, which seem to spring at once from the flower- stalk, without bracts or calyx. But, if they be examined, it will be found that three of these arise lower down than the others, and therefore partly enclose them ; so that these three are to be regarded (in spite of their colour) as sepals of the calyx ; and it may often be observed that, though coloured in their interior, they are greenish outside, especially along their middle. In the Fuchsia, a beautiful plant which may now be grown with little difficulty in our gardens, though formerly considered a rare exotic, the calyx is even more brightly coloured than the corolla. This change of colour, however, by no means disproves what has been said of the analogy between sepals and leaves ; since, as formerly noticed, leaves themselves occasionally undergo similar changes ; and the colouring principle seems to consist, in all cases, of nearly the same substance, in different states of chemical combination (. 386). Further, the calyx not unfre- quently returns to the form of true leaves, in flowers in which its regular appearance is very different; such irregular forma- tions, which are termed monstrosities, are in this, as in many other instances, very instructive to the Physiologist, in leading him to the knowledge of the true character of organs, of which the external form may have been greatly changed. 459. Similar remarks may be made upon the real nature of the petals of the Corolla. They are almost always coloured ; but they still preserve their leafy structure, having cuticle, sto- mata, parenchyma, and veins. It has been seen that, in the Tulip and Lily tribe, there is no essential difference between the sepals and petals ; what is true of the former, therefore, must be also true of the latter. Further, in the Paeony, the transition from the form of the sepal to that of the petal, is as gradual as that from the ordinary leaf to the sepal. If we trace the por- tions of the perianth from without inwards, we may observe that the green leafy sepals are slowly changed, in the first place by having their points and edges turned from green to pink, and becoming more delicate in their structure ; next the inner side is seen to be completely coloured, while the back is still greenish in its centre ; and finally the whole is converted into an ordinary TRANSFORMATION OP PETALS AND STAMENS. 299 petal. But even where the appearance of the petals is the fur- thest removed from that of ordinary leaves, it is very common to find monstrosities, which show that there is no essential dif- ference. The common Wood- Anemone, for example, not unfre- quently presents several varieties in the character of the sepals and petals, intermediate between what may be regarded as natural to them, and that of the ordinary leaves. Thus, the calyx may be converted into a whorl of true leaves, whilst the white petals have become green and resemble the ordinary sepals ; or the metamorphosis may have proceeded farther, and the petals, as well as the sepals, may have been converted into ordinary leaves. 460. The structure, appearance, and functions of the Stamens are so different from those of the parts of the perianth, that it would scarcely appear probable that they too are transformed leaves ; and yet this will prove to be the case. There are many flowers, in which the transition from the form of the petal to that of the stamen, is as gradual as those already described. This is the case, for example, in the Paeony; and it is still more evident in the com- mon White Water Lily, the principal stages of transformation in which are represented in the ad- joining figure. The petal, #, is first thickened near its point, as seen at 5, by a deposit of yellow substance, which, when exa- mined, is found to be pollen. This thickened part gains upon the expanded portion of the petal, which becomes contracted in a corresponding degree, as we advance nearer the centre of the flower ; until we arrive at the regular form of the stamen, d, in which we observe that the two thickened parts have met as anther-lobes, and that the leafy portion of the petal is contracted into the filament supporting them. The inner rows of stamens (of which there are several) are still more contracted, not being FIG. 95 STAGES OF TRANSFORMATION OF PETALS OF WHITE WATER LILY, INTO STAMENS. 300 TRANSFORMATION OF STAMENS. fully developed ; and here we lose all trace of the leafy ap- pearance. 461. Although the usual appearance of the stamens is such as was formerly described, there are several flowers in which they ordinarily have very broad expanded filaments ; and these organs are subject to the same kind of transformation into the leafy character, as are the portions of the calyx and corolla. The transformation of stamens into petals, in fact, is extremely com- mon ; it being generally in this manner that double flowers are produced from single ones. In the wild Rose, for example, we find but a single row of petals, surrounding a very large number of stamens ; whilst in the cultivated Rose of gardens, there are several rows of petals, and the number of stamens has propor- tionally diminished. The Rose is a flower, which is very liable to produce monstrosities or irregular growths ; and it is not uncommon to find this transformation more complete, the sta- mens, as well as the petals and sepals, being converted into true leaves, so that the flower is entirely green. The same is often the case with the Wood- Anemone. No further evidence then, is required to prove, that the elements of the leaf and the stamen must be the same (although their fully-developed forms are so different) ; and that these elements may be developed into one form or the other, according to circumstances, with which we are as yet only in part acquainted. 462. We now come to the Pistil, which occupies, as for- merly stated, the centre of the flower. In considering its real nature, it is always necessary to regard it as made up of a num- ber of separate carpels (. 434), whether or not they can be com- pletely distinguished ; just as the gamosepalous calyx and the gamopetalous corolla are considered as formed, by the adhesion of their several constituent portions. We have to examine, then, what is the real character of each carpel ; and this is sometimes manifested to us in a remarkable manner. When the carpels are distinct, and are fully developed, they not unfrequently pre- sent a very leafy appearance. Tfius, the pod of the Pea, when opened, is seen not to differ essentially from what a leaf, with its two edges rolled together, would be ; the prolongation of the TRANSFORMATION OF CARPELS. 301 stalk corresponds with the rnidrih, and the two valves of the pod are the two lobes of the leaf. Instances occasionally present FIG. 96 MONSTROSITY m THE PKA ; THK EDGES OF THE CAKPELS NOT UNITKD. themselves, in which this is seen more decidedly, from the want of development of the ovules, and the non-closure of the pod, so that its leafy aspect is less departed from. There are little pro- jections, however, from the thickened edges of this carpellary leaf, which show where the ovules should have been. A still more interesting monstrosity is almost constantly presented by the double Cherry. The centre of the flower is occupied by a small leaf in place of the usual carpel. This leaf (Fig. 97, a) has the two edges folded towards each other, and the midrib is greatly prolonged, having a little dilatation at its summit. If this be compared with the carpel of the cherry, seen at c, no doubt can be entertained that the two sides of the leaf answer to the walls of the ovary, the prolonged midrib to the style, and its dilated extre- mity to the stigma. In some in- stances the flower contains two FlQ ' ^ 302 REGULAR ARRANGEMENT OF THE PARTS OP FLOWERS such leaves ; and they are then always seen to present their hol- lowed faces towards each other, in the manner seen at b. This precisely corresponds with the position of the true carpels shown at d ; in which the suture or line of junction of the two edges, of each carpel is opposite to that of the other. If any further proof were required, of the carpel being a transformed leaf, it is afforded by the fact that, in Roses, Anemonies, Ranunculuses, and other such flowers, which are liable to have their stamens converted into petals, or into true leaves, the carpels not unfre- quently undergo the same changes, so that the whole flower is metamorphosed into a bunch of leaves, which are still arranged, however, on exactly the same plan with the parts of the real flower. 463. The usual arrangement of these parts corresponds pre- cisely with what was formerly stated, of the disposition of the leaves (. 303.) When the spiral, which may be regarded as their regular mode of arrangement, is converted into a whorl or verticil, by the non-development of the intervening part of the axis, and two or more of these whorls succeed one another, their several leaves do not correspond, in the direction in which they issue from the stem ; but are so placed, that the leaves of each are above or below the intervals between the leaves of the other. When this is the case, the whorls are said to alternate with each other. Now the regular flower may be considered as made up of five such whorls, arising from nearly the same part of the axis ; and they are disposed alternately with each other. Thus, the sepals of the calyx alternate with the bracts; the petals of the corolla alternate with the sepals, and are opposite to the bracts ; the stamens alternate with the petals, and are opposite to the sepals ; and the carpels alternate with the stamens, and are opposite to the petals. 464. This very simple law, regulating the position of the parts of the flower, is apparently subject, however, to many exceptions ; but these all arise from the interference of other causes. For example, the number of parts may be so much in- creased, that they cannot be all arranged in one whorl, and they then form additional verticils ; which, however, still follow the ARRANGEMENT OP THE PARTS OF FLOWERS. 303 FIG. 98. PLANS OP FLOWERS : a, Cherry; b, Squill same principle of arrangement. For example, the adjoining figure shows a plan (a) of the flower of a Cherry; in the outer circle are marked the places of the five sepals, and in the next those of the five petals which alternate with them. Within these, however, we find no less than twenty stamens ; but these may be regarded as composing four whorls with five in each, apparently blended together, however, by the closeness of their origin. The other diagram (&) is the plan of the flower of a Squill; in which, as in other Endogens, the parts are disposed in threes not in fives. The outer circle has three dots indicating the places of the three sepals ; and on the inner one the petals are indicated in like manner, and are seen to alternate with the former ; the stamens are six in number, and distinctly form two rows, of which the outer one is opposite to' the whorl of the calyx, and the inner one to that of the corolla ; and with this, again, the carpels would alternate. 465. An apparent irregularity, however, is more frequently produced by the absence of some of the parts, Thus, in the Primrose, there are five sepals, five petals, and five stamens ; but the stamens are op- posite to the petals, in- stead of alternating with them (Fig. 99 ; a). Now the explanation which the Botanist would offer of this irregu- larity, is, that there must be a row of stamens intermediate between the petals and the stamens, which, from some cause, have not been developed. And this is found to be really the case ; for in the Samolus, a plant otherwise formed upon the FIG. 99 PLANS OF FLOWSRS: a, Primrose; b, Samolus. 304 ARRANGEMENT OP THE PARTS OP FLOWERS. FIG. 100. a, plan of flower of Sage; 6, deve- lopment of stamens in allied genus. same plan as the primrose, five little scales, which are partly- developed stamens, appear in the situation of the absent row. In the Sage, again, we find a calyx of five sepals, and a corolla of five petals; but only two stamens are seen within (Fig. 100, ). Now, upon looking atten- tively at the inside of the tube of the corolla, two little scales are often to be seen growing in the place, where two of the deficient stamens should have been, that is alternating with the petals ; these two scales are frequently developed as perfect stamens, in flowers which are otherwise constructed exactly like the Sage (b) ; and even the fifth makes its appearance in some instances, exactly where it should regularly be found. Such deficiencies are often to be noticed ; thus in the genus Bauhinia, which has, properly, ten stamens arranged in two whorls, there are some species in which only three perfect stamens are developed(0),orevenbuta single one (6). Deficiency in the number of carpels in the pistil, is even more common ; and it is in fact rare to find a flower, which presents a structure that may be considered perfectly regular, as well in its form as in the number of its parts. "Without forming some such standard, however, it would be impossible to obtain a defi- nite idea of the nature of the deviations, of which some of the principal kinds will have to be presently considered. 466. One of the commonest of these deviations is that, in which the calyx appears to arise, not, as is usual, below the ovarium, but above it. In this case it will be found, that the real position of the parts is the same ; but that the perianth wraps round or encloses the ovarium, and spreads itself out only when FIG. 10] PLANS OK FLOXVEUS OF BAUHIMA. VARIETIES OF STRUCTURE. DISK. 3U5 freed from it. The stamens too, not unfrequently seem to arise from the corolla, instead of from the axis of the flower; but this effect is produced in a similar manner namely, by their adhe- sion at their lower part, to the inner side* of the petals. The stamens, again, sometimes adhere to each other, so as to form a complete tube, surrounding the pistil. 467. In the foregoing instances, the symmetry of the flower is not destroyed ; that is, it may be divided into two similar halves by a line crossing it in any direction. But there are many irregularities resulting from the unequal development of the different parts of the same whorl, and from the adhesion of these parts to each other in various ways ; so that the whole form of the flower sometimes appears completely changed, and there is only one direction, in which it can be divided into two equal halves. This is the case in the flower of the Pea or Bean, for example ; in which, as in other plants of the Papilionaceous group (so named from the resemblance of the flower to a Papilio or Butterfly), there is one broad petal standing erect, two sepa- rate ones termed the wings, which are prolonged from its base, and two others united together, forming what is termed the keel, which is enclosed between the last. 4G8. The flower is usually placed at the end of the flower- stem, or of its subdivision of it ; and the tendency in this stem to lengthen, appears to be checked by the development of a flower- bud. It commonly swells out at the insertion of the perianth, forming what is called the disk or receptacle; and in this, as for- merly stated, nourishment is frequently laid up, in the form of starch, for the development of the young ovules (. 285.) "This receptacle sometimes grows upwards between the carpels, and even encloses them. In other cases, it extends so much, as to separate the carpels from one another; this is the case in the Strawberry, of which the fruit is the swollen receptacle, whilst the little bodies scattered over its surface (commonly termed seeds) are in reality the carpels. Sometimes, however, it happens, that the flower-stem continues to grow between the points, from which the solids proceed ; and they are then separated from each other, just as are leaves in like circumstances (. 304). The spiral 306 TRANSFORMATIONS OP TOE ENTIRE FLOWER. line, in which the different parts of the flowers are inserted round the axis, then becomes very evident. This is not unfrequently the case in the Double Tulip, as well as in some Euphorbiums (Spurges); and as the parts of the flower are generally at the same time more or less changed into the leafy character, the resemblance of the whole flower to a leaf-bud or undeveloped branch then becomes very obvious. Sometimes after giving off the whorls of the perianth, the flower-stalk is prolonged through their centre, and bears another bud at its extremity; this is by no means uncommon in Roses. It is well known to Gardeners that, by a still further change, flower-buds may be actually converted into leaf-buds, and developed into true leaf-bearing branches ; a fact which sufficiently proves, that every part of the flower is formed out of the same elements with leaves, and that the development of either may take place according to circum- stances. Hence we know why a difference in the amount of nutrition which the plant receives, should influence its tendency to the production of flowers and fruit. It has been stated that, in each of the parts of the flower, there is a tendency to revert to the leafy form ; and this is especially the case with the stamens, which are often converted into petals (thus changing a single flower into a double one), when the plant is transferred from the poor soil, in which it may be naturally growing, into the rich mould of a garden. Now if a plant be over-supplied with nourishment, it will run to leaf, as it is termed, that is, it will develope too many leaf-buds, and will not put forth flowers ; so that, in order to make it bear fruit, it is necessary to diminish its quantity of sap ; one method of effecting which, is to dig a trench at a certain distance round the bottom of the trunk, so as to cut off part of the supply it receives from the roots. 469. It might be objected to the statements here made, that the pollen and the ovules are so different from anything which the leaf naturally produces, that no analogy can be imagined between organs bearing these, and the ordinary leaves. But, if the structure of the pollen-grain be considered, it will be per- eeived to correspond precisely with that of other cells of cellular tissue ; differing chiefly in its power of separating itself from the NATURE OF OVULES. FORMATION OF FRUIT. 307 rest, and of sending forth little granules which are to form new plants, instead of adding to the number of cells in the parent structure. Every cell of the Confervas, it will be recollected (. 424), may be regarded as essentially a pollen-grain ; and therefore the difference cannot be really so great as it appears. Further, in regard to the ovules, the fact heretofore mentioned (. 240) that certain leaves have the power of producing little buds from their edges, becomes of great interest; for, if the ovules could be regarded as at all analogous to buds, it is evident that their situation on the edges of the carpellary leaf would quite correspond with that of the buds of the 'BryopJiyllum^ or of the Bog Orchis. And it has been proved by the occurrence of some curious monstrosities, that this is a real analogy ; for a seed-vessel of Mignionette has been known to bear a set of little buds at the edges of its carpellary leaves, arranged just as the ovules should have been. 470. We have in the last place to consider the structure of the Fruit, which is the mature or ripened ovary containing ferti- lised seeds. This frequently differs remarkably from the ovary, which the centre of the flower contained, both in its external appearance, and in the arrangement of its interior. For example, the Cherry, Plum, Almond, or other stone fruit, is formed by a remarkable change in the substance of the carpellary leaf;, the internal surface of this becomes hardened into the stone, whilst the external remains as a thin cuticle or skin ; and the pulp of the fruit is formed, by the increase of the parenchyma or fleshy tissue of the leaf. Here each carpel originally contained several ovules, but only one of them is usually developed. In the ovary of the Chesnut, there are originally seven carpels or cells with two ovules in each, whilst the ripe fruit consists of but one cell and one seed ; so that no fewer than six cells and thirteen ovules are suppressed, in order to enable a single ovule to grow and be matured. It is not uncommon, however, to find two or even three Chesnuts within a single shell, separated by slight parti- tions. The fruit of the Orange, as formerly mentioned, consists of the carpels, surrounded by the external coat of the ovarium ; and having the space between their inner wall and the seeds they x 2 308 STRUCTURE OF FRUIT. contain, filled up with a very succulent cellular tissue. On the other hand, in the Apple, the carpels lie in the centre of the fruit, and their walls are somewhat horny ; the fleshy substance of the fruit is formed by the calyx, which is adherent to the exterior of the ovary; and the parenchyma between its two surfaces swells out in ripening, in the same manner as does that of the carpellary leaf of the Plum. In the Medlar, the carpels have a hard or bony covering, and they lie separately in the midst of the pulpy envelope, which they acquire in like manner from the calyx. In the Strawberry, as just now mentioned (. 468), the carpels are separated from each other by the recep- tacle, the expansion of which forms the fleshy part of the fruit. In the Raspberry and Blackberry, on the other hand, the recep- tacle is the white fleshy stalk which occupies the centre of the fruit ; and the pulpy portion consists of the carpels enclosing seeds. The Custard- Apple of the "West Indies is formed on this Fie. 102. ANONA SQUAMOSA, OR CUSTARD-APPLB : a, the flower ; 6, fruit ; c, the same in section, showing the position of the seeds ; d, seed ; e, section of the seed. last plan ; the edible portion consisting of the fleshy carpels which are attached to a slender receptacle. The pods of the Pea, Laburnum, and other Leguminous plants, again, are single car- pels, which sometimes grow to a great length, and contain many seeds. In the Bread-fruit (Fig. 103) and Mulberry, the edible portion is formed by the cohesion, into a single mass, of the floral envelopes and ovaria of a large number of flowers, arranged on a central fleshy column or spike. In the Fig. on the other hand, the fleshy receptacle encloses the flowers, which are situated in the interior of the fruit. A great many more varieties might be enumerated; but the mention of these will serve to give an idea DISPERSION OP SEED. 309 of the mode, in which the very curious transformation of the ovary into the fruit takes place. FIG. 103. ARTPCARPUS INCISA, OR BREAD-FRUIT. 471. When the seeds are ripe and ready to be dispersed, the carpel usually splits either along the suture, or in the opposite direction, in order to set them free. There are many curious provisions for their dispersion to a great distance from the parent. Some of these, depending on the movements of the capsule, have already been explained. Many seeds are winged, that is, are furnished with a little expansion on each side, fitted to catch the wind ; and thus they are wafted to places far distant from those in which they were produced. A very common provision is that of which the Dandelion seed is an example. This, as is well known, is furnished with a very light downy appendage, by which it is floated along with the slightest breath of air ; this appendage is nothing else than a peculiar form of the calyx, which remains adherent to the seed, until it is deposited in the soil. Other seeds, again, are conveyed by the waters of streams and rivers, into which they fall ; and take root, when left by the current upon a congenial soil. Some are even capable of resisting the influence of the waters of the sea ; and in this manner it is, that the coral islands, which are gradually appearing above the sur- 310 DISPERSION OP SEED. CONCLUSION. face of the Pacific Ocean, are speedily covered with a crop of luxuriant vegetation. Birds, too, are very important agents in diffusing the various species of plants ; some of which are scarcely dispersed in any other way. They carry off the whole fruit to a convenient place, and drop the stone when they have eaten the pulp ; or they eat the whole, and the seed, being undigested on account of the hardness of its coats, falls into the ground when voided by them. Some seeds will not readily germinate, until they have undergone this process. When it is considered that from a single seed as many as 30,000 or 40,000 new individuals of some species may be produced in a single year, it will be perceived how abundantly the Creator has provided for the con- tinuance of their race, and how unlikely is their extinction, without some great convulsion of Nature. 472. The Reproductive System of Vegetables, then, counter- acts in its operation the effects which would otherwise speedily result from the law, which the Creator has impressed on all organ- ized structures ; that law of limited duration, which renders their death and decay as complete a portion of the series of actions they exhibit, as are the wonderful phenomena in which they are concerned during life. By this counterpoise, all limit to the continuance of races is removed, except such as is inter- posed by some causes beyond. The records of the history of the Earth, which are brought to light by an examination of the rocks that appear at its surface, afford abundant evidence, that vast con- vulsions must have formerly occurred, involving the Vegetable as well as the Animal kingdom; and that, at each of these, many races of Plants were utterly destroyed ; so that there is now probably not a single species remaining, of these which first covered the dry land with verdure, when it was lifted from the depths of the ocean by Almighty Power. Such a convulsion will again occur. A time is foretold when " the elements shall melt with fervent heat, and the earth also and the works that are therein shall be burned up." But the immortal soul of Man will survive this general conflagration, and his faculties will receive that full development, for which his present existence is but a state of preparation. ADDENDUM. THE third Edition of Professor Liebig's Agricultural Chemistry, recently published, contains much additional evidence in support of the view entertained by him, and embodied in Chap. VI. of the present Treatise, that the relative fertility of different soils depends, in great degree, upon the supply they yield of the mineral ingredients, which are required by the crops of vegetables raised upon them. It has been already shown (. 186) that the carbon of plants is derived rather from the atmosphere than from the soil ; the latter having for its chief purpose, to afford a supply to the young plant, which is repaid with interest, when its full growth has been attained, by the fixation of carbon from the air through the leaves ; so that the quantity of carbon in a soil, which supports a flourishing vege- tation, is continually increasing rather than diminishing. By similar observation upon an extended scale, it may be shown that their nitrogen also is chiefly derived from the atmosphere. For centuries past, a very large, quantity of cheese has been annually exported from Holland, the produce of the cows fed upon its pastures. Now the fertility of these pastures has not diminished, but has rather increased ; notwithstanding the withdrawal of so large a quantity of a highly-azotised substance, the casein or cheesy matter. The cows are permitted to remain on the pastures day and night ; and they thus return to the soil, in their solid and fluid excrements, nearly all the mineral matter which has been withdrawn from it, with a considerable proportion of the elements of its organic compounds. The nitrogen as well as the carbon removed from it, whether in the form of milk, animal flesh, or the products of respiration imparted to the atmosphere, must be again obtained by the soil from the atmosphere ; since there is no dimi- nution in the amount of these elements through a long period of time. But if the mineral matters, which cannot be obtained from the atmosphere, were not restored in the manure, a rapid diminution in fertility would certainly ensue ; this having occurred in many similar cases. It appears from recent chemical analyses of various kinds of 312 ADDENDUM. vegetable substances, that we are not to suppose that Wheat and other kinds of Corn require more nitrogen, than do the herbaceous plants raised for the support of cattle. The following table shows the proportion of nitrogen to carbon in the entire plants of dif- ferent species ordinarily cultivated. With every 1,000 pounds of carbon, we obtain From pasture-land, in Grass 32*7 pounds of carbon. From cultivated fields, in Wheat 21 '5 Oats 223 Rye 15-2 ,, Potatoes 34-1 Beetroot 39'1 Clover 44 Peas 62 The proportion of nitrogen is much greater in the seeds of the Corn-plants, in which is concentrated most of the azotised matter, which is elsewhere diffused through the entire structure. It is by far the highest in Peas and Beans ; which are nevertheless grown advantageously between Wheat-crops, and which do not require any animal manure thus showing that they do not exhaust the soil of its azotised matter. But the general principle formerly stated (. 213), respecting the influence of manures, which readily yield carbonic acid and ammonia, in accelerating the growth of plants, and rendering it more luxuriant, is not affected. Still the manures which are richest in this respect will be totally ineffica- cious, if there be not at the same time an ample supply of the mineral ingredients, which the particular species of plant requires. It has been mentioned (. 200 207) that the chief of these ingredients are Silex, the Alkaline Carbonates, and Phosphate of Lime ; and recent observations show, that it is chiefly in affording an increased supply of the two first, that the good effects of burn- ing a stiff clayey soil, and of manuring it with lime, two processes which have long been advantageously practised, really consist. Owing to the habit which prevails in this country, of allowing the excrements of man to run to waste, instead of committing them again to the soil, a very large quantity of phosphate of lime is con- tinually being withdrawn from it ; and if it were not for the great importation of bone-earth from foreign sources, the amount of corn grown in this country would rapidly diminish, for want of this most important ingredient. It has been suggested by Professor Liebig, that the large beds of fossil excrements (coprolites), which are found in some parts of Britain, might be advantageously resorted to for the needed supply. CHAPTER XIII. GENERAL PRINCIPLES OF CLASSIFICATION. 473. THE term BOTANY is properly applicable to the whole of the science which includes the study and investigation of the Vegetable Kingdom. Hence the examination of the internal structure of Plants, and of the various processes concerned in their growth and reproduction, to the description of which, under the title of Vegetable Physiology, the former part of this Treatise has been devoted, strictly constitutes but a branch of the Science of Botany, and may be designated Structural and Physiological Botany. But by those who have made the study of the Vegetable Kingdom a means of interesting recreation, rather than a professed object of pursuit, and even by some who have considered themselves scientific Botanists, this branch has been entirely overlooked : and the whole attention has been devoted to the other department of the Science, which concerns the arrangement or classification of the many thousand species (. 15) of Plants existing on the surface of the globe, into groups or divisions ; each of which includes a number of species, that have certain characters in common, and that differ from those of other groups. The advantages of such a plan, in the saving of time and labour, are obvious. If all the peculiarities of every species of plant had to be studied and recollected by themselves, it would require a long acquaintance and a retentive memory, to become master of the characters of the 1400 or 1500 species of Flowering-Plants which our own country produces ; and when this number is multiplied by a hundred, which it probably must be to represent the amount of species existing on the entire globe, it is obvious that no single mind could be capacious enough to grasp the vast amount of detail thus accumulated. 474. It is the business of the Botanist, therefore, in the first 314 COLLECTION AND ARRANGEMENT OF PLANTS. place, to collect Plants from all sources open to him ; and he then arranges them according to their species. Thus, we will sup- pose that he has collected all the plants of Great Britain, and that he has obtained a corresponding series of the plants of France. Upon bringing them together, he would find that many species are common to the two countries ; but that some are peculiar to Britain, others to France. If he obtained, in addition, a col- lection of Spanish plants, he would find that some of the species common to Britain and France are contained in it also ; and that some species not known in Britain are common to France and Spain ; but he will find many peculiar to Spain. Proceed- ing thus orer the whole world, he would gradually increase his number of new species ; at the same time adding considerably to the number of specimens of some which he would find very ex- tensively diffused. He would find a few similar species almost everywhere, these being the kinds most capable of adapting themselves to varieties in soil, climate, &c. ; whilst, on the other hand, he would find many of a very limited distribution, being restricted to some small extent of country, in which alone they can find the conditions necessary for their growth. 475. The greatest difficulty in this part of the investigation consists in the discrimination of species really distinct, that is to say, of races which have maintained their distinctive peculiarities, so constantly, that they must be considered as having had ori- ginally different stocks, from those varieties (. 16), which may often present differences really greater in amount than those which exist between many undoubtedly distinct species, but which all sprung from the same original stock. Thus, for ex- ample, a collection of plants from different parts of India would contain many specimens presenting such marked differences, that the inexperienced Botanist would not hesitate to set them down as distinct species ; yet to one who has carefully examined the subject, and has made himself acquainted with the variations produced by the differences in soil and climate so striking in this extensive tract, it becomes apparent that they are all mem- bers of the same. There is, too, in many species a remarkable tendency to run into spontaneous variations, for which no exter- DISTINCTION BETWEEN SPECIES AND VARIETIES. 315 nal influences will account. Thus the seeds of the same indi- vidual of the beautiful Fuchsia, now naturalised in our green- houses and in the open air of the milder parts of Britain, have been known to produce plants, whose flowers differ so much in shape and in the proportional length of the calyx and corolla, that, if these had been collected and compared without the know- ledge that they had been produced from one plant, they would have been regarded as distinct species, perhaps even (so striking is the difference) as distinct genera. Nearly the same is the case with another South American Plant now much cultivated in Britain, the Calceolaria or slipper-shaped flower ; of which an immense number of varieties, differing widely in the shape as well as the colour of the flower, are now known, almost every Horticultural Exhibition having a new one : and the beautiful South American Amaryllis has a like tendency, of which the gardener has taken similar advantage. 476. Hence in discriminating what are real species from what are simply varieties, the Botanist is treading on very insecure ground, until he has ascertained, for every species, its tendency to run into varieties of form, whether spontaneous, or induced by change of external conditions. His greatest difficulty arises from those cases, in which have arisen what are termed permanent varieties, which reproduce themselves with the same regularity as do real species. An instance of this in the Animal Kingdom is that of the different races of men, which are respectively distin- guished by marked peculiarities, that are regularly repeated through each generation ; so that many naturalists have been inclined to regard them as really distinct species. There is, however, good evidence (independently of the Mosaic History) to prove that they have all descended from a common stock. Precisely the same is the case in regard to Plants ; many races of which, even in Britain, are still under discussion amongst Botanists ; some maintaining that they are distinct species, and others that they are but varieties. Thus of the Willow, 71 species have been stated by one authority to exist in Britain, whilst another reduces them to 29. The genus Rubus or com- mon Bramble has been thought to contain 21 British species, y 2 3H COMBINATION OF SPECIES INTO GENERA. which are probably reducible to 6 or 8. These details are here introduced, for the purpose of putting the young Botanist on his guard, against the tendency to multiply species, which is now prevalent among superficial writers, and which is still further encouraged by Gardeners, who give new specific names to such varieties as those just alluded to, and even to hybrids between these (. 454). 477. When the Botanist has satisfied himself regarding the species which he has collected, his next step is to combine those amongst which he finds the greatest resemblance, into genera. Now in this process he must not be altogether influenced by simi- larity in their general external aspect ; for this will often con- ceal great differences in their most important organs. There are certain parts which furnish essential characters, without similarity in which it would be wrong to associate species, how- ever alike in other respects, in the same genus ; and, on the other hand, there are parts so susceptible of variation, that the differences between them must be very striking indeed, to war- rant the plants being arranged under different genera, when they agree in what have been termed the essential characters. Thus, for instance, the general outline of the leaf has been stated to be often subject to great variety, in accordance with the degree in which the space between the veins is filled up with fleshy parenchyma (. 234, 5); and in most cases, a difference in the outline of the leaves of two plants, the distribution of the veins remaining the same, would not alone serve to cause two plants exhibiting it to rank even as distinct species. But any consider- able alteration of the veining would be held sufficient for such a separation ; though the two plants, if agreeing in the structure of their organs of fructification, would still be placed in the same genus. On the other hand, a marked and constant dif- ference in the organs of fructification would be rightly held sufficient to place the two species in different genera, even though the form and veining of the leaves might be precisely the same, On the relative value of the characters furnished by the different organs more will hereafter be stated. 478. Even when thus grouped together into genera, however, FORMATION OP ORDERS AMD CLASSES. 317 the number of objects, which the Botanist has to study, remains by far too great for convenience ; and he next forms his genera into orders, and combines these orders into classes^ according to their respective correspondence and difference in certain charac- ters of a still more general nature. Now in this process he may follow two very different plans ; and upon these are founded the two systems of classification which are now in vogue. One of these is termed the Linnaean System, after its founder; or the Artificial System, from its character : the other is termed the Natural System. In the Linnaean System, a small number of characters chiefly the number of stamens and pistils is taken as the standard ; and the whole Vegetable Kingdom is distributed underclasses and orders, according to the correspondences and differences among the several genera in these respects, no regard whatever being had to any other characters. In the Natural System, all the characters of the genera are studied ; and those are united into orders, which present the greatest correspondence in the characters that are regarded as of the most importance : on the same principle, the orders are united into classes. If the former plan be followed, genera most widely differing in their structure and physiological characters are often brought together, and others which are nearly allied are frequently separated to a great extent ; so that in fact, it is very common to find, that nothing can be stated as true of all the plants included in a Linnaaan order, except that they have a similar number of sta- mens and pistils. On the other hand, in the Natural System, the number of characters, in which there is a general agreement among all the plants of a particular order, is so great that, to say that the plant belongs to a certain order, is at once to give the greater part of its description. This is the case also in the highest or most general groups. For instance, to say that a par- ticular species is an Exogen, is at once to make known the structure of its stem and the mode of its increase, to express the important fact that it has two cotyledons or seed-leaves, to render it most probable that the arrangement of the veins in its leaves is reticulated rather than parallel, and to intimate that the parts of its flowers are likely to be arranged in fives or fours, rather than in threes. 318 CONNEXION OF STRUCTURE AND PROPERTIES. 479. There is a point of agreement among the plants brought together in Natural Orders, which is of the greatest practical importance. This is, that those which agree in structure almost invariably correspond in properties also. For instance, the whole of the Papaveraceae or Poppy tribe possess narcotic properties ; all the Ranunculaceae or Crowfoot tribe are acrid ; whilst all the Malvaceae or Mallow tribe are destitute of unwholesome proper- ties. Thus, when a plant is recognised as a member of a parti- cular Natural Order, an almost certain account may be given of its properties, whether it is likely to be injurious or wholesome, to furnish valuable medicines, or important articles of food. It must be remembered, however, that the peculiar properties of the plant do not pervade every portion of it ; and that it may hence be possible to obtain wholesome nutriment, even from members of orders most distinguished for their deleterious pro- perties. Thus the Potato belongs to the order Solaneae, which contains the Deadly Nightshade, Henbane, and other poisonous plants ; but the edible part of it, which is a deposition of starch for an express purpose (. 337), is free, or nearly so, from the narcotic properties which exist in the stems and leaves. Indeed, as a general rule, such depositions of starch may supply whole- some food in any order, more especially if care be taken to free them from any juices they may contain ; thus the Cassava, which furnishes one of the most important articles of food to the inha- bitants of many tropical countries, is obtained from a plant of the order Euphorbiaeece or Spurge tribe, which is distinguished for its very acrid qualities : and these are principally restricted to the juice expressed from the meal after it has been ground. 480. The Linnaean system, however, is not without its ad- vantages for particular purposes. To a person commencing by himself the study of Systematic Botany, desirous of making him- self acquainted with the names and characters of the plants he may meet with in his walks, and not ambitious of extending his studies to the higher parts of the science, the Linnaean system, when applied with the aid of books, possesses facilities which are (at present at least) greatly superior to those afforded by the other, and which are well calculated to encourage a learner. To count the number of stamens and pistils is generally a very easy USE OF THE LINN.fi AN SYSTEM. 319 process ; this at once establishes the class and order ; and nothing then remains, but to determine the genus and species, which (among the comparatively small number found in Britain) a little practice in the examination of characters will enable any intel- ligent person to do, with tlie aid of books in which these are laid down. The habit thus gained of discriminating characters, and of applying terms, is a most valuable preparation for the study of the Natural System when opportunity presents itself. It must be constantly borne in mind, however, that the utmost use which can be made of the Linnsean system, consists in the assistance it affords in the discovery of the name of an unknown plant ; and, until this has been made out, the previous determination of its class and order gives no indication of its general structure and properties (not even making it apparent whether it is an Endogen or an Exogen, a Dicotyledon or a Monocotyledon), since under the same head are grouped genera of the most opposite character. It may be said that it serves as a sort of Alphabetical index to a book, enabling the reader to turn to any part of it he wishes, by looking out the subject in the order of its first letters, but giving no idea whatever of the general scope of the book, nor of the mode in which its subjects are arranged. 481 . The Linnaean System is liable to many imperfections and difficulties in its application, even in the limited circle of British Plants ; for example, the number of pistils is liable to be altered in any species by the more or less complete adhesion of the car- pels; and that of the stamens may also vary in the different species of the same genus, and even among the different indivi- duals of the same species, or even (in some instances) among the different flowers of the same stem. The adoption of characters thus liable to vary cannot, therefore, but sometimes lead to con- fusion. For instance, of the genus Polygonum, of which the several British species are known by the names of Bistort, Buck- wheat, Persicaria, &c., one has always, and two others have occasionally, eight stamens ; whilst in the rest the number varies from five to ten. As eight seems to be the most regular num- ber, the genus is placed in the class Octandria : and although its styles are sometimes only two in number, it is placed in the order Trigynia, because they are more commonly triple. Now if a 320 IMPERFECTIONS OP THE LINNJSAN SYSTEM. student meet with a specimen which has five, six, or ten stamens, he will vainly search for its character among the genera of the Linnaean class to which it would seem to belong ; and unless he happen to consult a book which makes special mention of the genus in these several classes, he will be altogether at fault. Suppose that some more knowing Botanist tells him that his plant is a Polygonum, he will again turn to his book, wondering how he could have overlooked it ; but he will find the genus in the class Octandria, in spite of the different number of stamens in the specimen before him : and he will then learn that it is placed in the genus Polygonum on account of its strong general resemblance to other Polygonums, although differing from them in characters which are ordinarily considered as sufficient to esta- blish classes and orders. Again, the greater part of the species of the genus Rhamnus (Buckthorn) possess both stamens and pistils in the same flower ; but the species most commonly known in this country on account of its purgative properties is Dioecious, the staminiferous flowers being on one plant, and the pistilliferous on another (. 435). The student who meets with it, therefore, would seek for it in the class Dicecia, where he would be disap- pointed as before ; since, as in most species the flowers are com- plete, it is placed in the class and order to which the number of its stamens and pistils would refer it. 482. Such exceptional cases occur much more frequently than is commonly supposed. It has been proved that, in fourteen divisions of the Linnaean system, including 173 British genera, there are no less than 43 exceptions, one-quarter of the whole; and that out of 274 genera of North America, belonging to eighteen Linnaean sections, there are 78 exceptions, rather more than a quarter. These facts are important, both as preparing the student to meet with such difficulties, even in the study of the Linnaean system, which is generally considered so easy of application ; and also as showing the imperfection of the system itself, which is of no value whatever, beyond the temporary pur- pose of facilitating the early studies of the Botanical Student. In well-arranged descriptions of British Plants (such as Hooker's British Flora, which may be strongly recommended for this pur- pose) the most perplexing of these cases are noticed, in such a PRINCIPLES OP THE LINN^EAN SYSTEM. 321 manner as to prevent the loss of time and labour, in vain attempts at discovering genera in wrong classes, or species in wrong genera. 483. Entertaining, as the writer does, from some experience in the matter, the foregoing opinion of the advantages of the Linnsean System for a beginner, it is desirable here to give an outline of the principles upon which its divisions are founded, which may serve as an introduction to the regular systematic treatises on the subject. The Phanerogamia or Flowering Plants are distributed under twenty-three Classes, all of which are cha- racterised either by the number or particular arrangement of the stamens. In the first twelve of these, number alone is regarded. Their names are formed by the combination of the Greek numeral expressing the required number, with the termination andria^ which has reference to the supposed male office of the stamens in the process of fertilization. These classes, therefore, stand simply as shown in the following figures : FIG. 105. FIG. 104. Digynia. Monogyaia. CLASS I. MONANDRIA. One stamen. Orders Monogynia and Digynia. Trigynia. Digynia. Monogyaia. CLASS II. DIANDRIA. Two stamens. Order s- Monogynia, Digynia, and Trigynia. FIG. 106. Trigynia. Digynia. Monogynia. CLASS III TRIANDRIA. Three stamens. Orders Monogynia, Digynia, and Trhrynla. 322 CHARACTERS OP LINNJ2AN CLASSES. Fio. 107. Tetragynia. Digynia; Monogynia. CLASS IV. TBTRANDRIA. Four stamens. Orders Monogynia, Digynia, and Tetragynia. Fio. 108. Trigynia. Digynia. Monogynia. Pentagynia. Tetragynia. CLASS V.-PENTANDRIA. Five stamens. Orders Monogynia, Digynia, Trigynia, Tetragynia, Pentagynia, and Polygynia. Fio. 109. Trigynia. Digynia. CLASS VI HBXANDRIA. Six stamens. Orders Monogynia, Digynia, Trigynia, and Polygynia. Fio. 110. Digynia. Monogynia, Heptagynia. Tetrauynia. CLASS VII. HEPTANDRIA. Seven stamens. Orders Monogynia, Digynia, Tetragynia and Heptagynia. CHARACTERS OF LI> 7 KEAN CLASSES. FIG. 111. 23 Tetragynia. Trigynia. Digynia Monogynia CLASS VIII OCTANDRIA. Eight stamens. Orders Monogynia, Digynia, Trigynia ; and Tetragynia. FIQ. 112. Hexagynia. Trigynia. Monogynia. CLASS IX. ENNBANDRIA. Nine stamens. Orders Monogynia, Trigynia, and Hexagynia. FIG. 113. Monogynia. Decagyoia. Pentagynia. Trigynia. CLASS X. DECANDRIA. Ten stamens. Order* Monogynia, Digynia, Trigynia, Penta- gynia, and Decagynia. 324 CHARACTERS OF LINN^AN CLASSES. FIG. 1J4. Pentagynia. Tetragynia. CLASS XL DODECANDRIA. Twelve' to nineteen stamens. Orders Monogynia, Digynia, Trigynia, Tetragynia, Pentagynia, Hexagynia, and Dodecagynia. FIG. 115. Polygynia. Di-Pentagynia. Monogynia, CLASS XII. ICOSANDRIA. Twenty or more stamens inserted into the calyx. Monogynia, Di-Pentagynia, and Polygynia. Orders To the last mentioned class, however, another character belongs; for in the next class, POLYANDRIA, the number of stamens is also twenty or more. They are distinguished by the mode of insertion of the stamens ; these appearing to arise from the calyx in the former, and from the disk or receptacle in the latter. This distinction, which will be hereafter shown to be important in the Natural System, will be at once understood by comparing a true Rose, Plum, Cherry, or Pear blossom, with a Christmas Rose, CHARACTERS OF LINNJSAN CLASSES. 325 an Anemone, or a Paeony ; when the calyx and corolla of the former are pulled off, they carry the stamens with them ; but they may be entirely removed from the latter, leaving the stamens attached to the disk. These two classes will, therefore, stand as follows : FIG. 116. Polygynia. Penta^ynia- CLASS XIII. POLYANDRIA. Twenty stamens or more, Inserted into the receptacle. Orders Monogynia, Digynia, Trigynia, Tetragynia, Pentagynia, and Polygynia. The next two classes are characterised by peculiarities in the proportional length of the stamens, as well as in their number. Those which are longer than the rest are said to be in power ; and the termination dynamia is applied to the number of these, in order to designate their peculiarity. Fro. 117 Angiospermia. Gymnospermia. CLASS XIV. BIDYNAMIA. Four stamens, two longer than the others. Orders Gym- nospermia and A ngiospermia. 326 CHARACTERS OF LINN^EAN CLASSES. FIG. 118. Siliquosa. Siliculo CLASS XV. THTRADYNAMIA. Six stamens, four longer than the others. Orders Siliquosa, Siliculosa. The three following classes are characterised by the more or less complete union of the filaments of the stamens into bundles, or brotherhoods ; on account of which the termination adelphia is applied to the number of such bundles. Fro. 119. Polyandria. Uodecandria- Decandria. CLASS XVI. MoNADELPHfA. Stamens united into a single bundle, forming a tube which surrounds the style. Orders Triandria, Pentandria, Hexandria, Heptandria, Octandria, Decandria, Dodecandria, and Polyandria. FXG. 120. CLASS XVII, Decandria. Octandria. FA. Stamens united into two bundles. Hexandria, Octandria and Decandria. Orders Pen tan dr ia, CHARACTERS OF LINNJSAN CLASSES, 327 FIG. 121. Polyandria. flecandria. CLASS XVIII. POLYADELPHIA. Stamens united into several bundles. Orders Decandria, and Polyandria. In the next class, it is the anthers which form the tube ; and the name applied to it signifies a growth together. In the suc- ceeding class, the stamens and the pistil grow together ; and the name gyn-andria refers to this union of the male organs with the female, the latter being designated by the first syllable, which will presently be seen to be much employed in the description of the orders. Fm. 122. Superflua. -ffiqualis. CLASS XIX. SYNGENESIA. Stamens united by their anthers into a tube. Orders JSqualis, Superflua, Frustranea, and Necessaria. FIG. 123. CLASS XX. GYNANDRIA. Stamens and pistils grown together. Orders Monandm, Diandria, and Hexandria. 328 CHARACTERS OP LINN^EAN CLASSES. The three remaining classes are characterised by the separation of the staminiferous and pistilliferous flowers ; the import of the names of the first two has been already explained (. 435). Fie. 124. Polyandria. Monadelphia. CLASS XXI. MONCECIA. Stamens and pistils in separate flowers, but both growing on the same plant. Orders Monandria, Diandria, Triandria, Tetrandria, Pentandria, Hexandria, Octandria, Icosandria, Polyandria, and Monadelphia. CHARACTERS OF LINN^EAN CLASSES. IG. 125. 329 Monadelphia. CLASS XXII. DKECTA. Stamens and pistils not only on two flowers, but these flowers on two different plants. Orders Monandria, Diandria, Triandria, Tetrandria, Pentan- dria, Hexandria, Octandria, Enneandria, Decandria, Dodecandria, Icosandria, Polyan- riria, and Monadelphia. FIG. 126. Diwcla. CLASS XXIII POLYGAMIA. Stamens and pistils sepa- rated in some flowers, united in others, either on the same plant or on two or three different ones. Orders Monoeeia and Dicecia. 330 CHARACTERS OF LINN JS AN ORDERS. 484. The Orders, or subdivisions of the classes, are generally founded upon the number of the styles, or (if these be not pre- sent) of the stigmas ; or upon certain peculiarities of the seed- vessel. In the first thirteen classes, the number alone is regarded ; and the orders are designated, as before, by the Greek numerals, with the termination gynia, which refers to the supposed female character of the pistil. Order 1. Monogynia, One Style 2. Digynia, Two Styles 3. Trigynia, Three Styles 4. Tetragynia, Four Styles 5. Pentagynia, Five Styles 6. ffexagynia, Six Styles 7. Heptagyriia, Seven Styles 8. Octogynia, Eight Styles 9. Enneagynia, Nine Styles 10. Decagynia, Ten Styles 11. Dodecagynia, Twelve Styles 12. Polygynia, More than Twelve Styles. It will be evident, from the description of the structure of the pistil formerly given (. 434), that the number of styles affords no indication of the character of the ovarium. Thus, the ovarium may be formed of many carpels, the divisions between which remain as distinct partitions, whilst the styles and stigmata of all these may have coalesced into one pillar ; so that we may have a single style with a many-celled seed-vessel. On the other hand, the walls of the carpels may form but incomplete partitions, so that the cavity of the ovarium is undivided (Fig. 50) ; whilst the styles and stigmata may be numerous. It will hereafter be shown that the structure of the ovarium itself is a much less variable character than the number of styles, which is liable to alteration in many species (like that of the stamens) through the adhesion or the non-development of some of them. In the class DIDYNAMIA, the characters of the orders are drawn from the structure of the seed-vessel. The first, Gymnospermia, or naked- seeded, includes those in which the ovary has four carpels, each enclosing a single seed ; and this, when mature, fills up the cavity in such a manner, that the wall of the seed-vessel appears like an outer coat to the seeds, which thus do not seem to have any NATURAL GROUPS IN LINNJEAN SYSTEM. 331 other envelope. We shall hereafter find that the only true naked-seeded plants are the Coniferae or Pine tribe, and its allies, in which the seeds never are enclosed in a seed-vessel. The second Order, Angiospermia, includes those Didynamia which have a distinct seed-capsule, usually two-celled, each cavity containing many seeds. In the next class, TETRADYNAMIA, there are also two orders, distinguished by the form of their pod-like seed- vessel; the first, Siliguosce, having a long-pod; the second, Siliculoscp^ a short one. The Orders of the classes, MONADEL- PHIA, DIADELPHIA, PoLYADELPHiA, depend upon the number of their stamens ; and they have the same names as the first thirteen classes, the number of stamens, however, being never less than five. The subdivision of the class SYNGENESIA (as now under- stood) is rather complex ; and, as it is nearly the same in the Natural System, it will be better explained under the Order Composite. The orders of the classes, GYNANDRIA, MONOECIA, and DICECIA, are distinguished by the number of stamens, and are consequently Monandria^ Pentandria, &c. Those of the class POLYGAMIA are the Moncecia, in which the same plant bears staminiferous, pistilline, and complete flowers ; and the Dicecia, in which these occur on different individuals. 485. There are many of these orders which form groups truly natural ; that is, which consist of genera having a large number of points of agreement with each other, independently of the characters on which the subdivision is founded. For example, one portion of the class PENTANDRIA, order Digynia, corresponds witli the Natural Order Umbelliferce (including the Parsley, Carrot, Hemlock, Parsnep, &c.) ; the Class TRIANDRIA, order Digynia, very nearly corresponds with the natural group of Grasses, all these having three stamens and two styles, which combination is not found in any other plants. The DIDYNAMIA Gymnospermia, again, are the same with the Natural Order Labiatce, to which belong the various kinds of Mint, Thyme, Dead Nettle, &c. ; and the class TETRADYNAMIA corresponds with the natural Order Cruel/eras, to which belong the Mustard^ Cress, Cabbage, Turnip, Stock, Wall-flower, &c. From the predominance of the number three and its multiples in the parts z 2 332 IDEA OF NATURAL ARRANGEMENT. of the flower of Endogens, we find most of this group included in the classes Triandria, Hexandria, and Enneandria ; whilst the prevalence of the numbers four and five among Exogens, causes the classes Tetrandria and Pentandria, Octandria and De- candria, with Icosandria and Polyandria, to contain a very large proportion of that division. But the Linnaean system often brings together Exogens and Endogens into close contact ; be- sides breaking up the natural alliances of each, so as to scatter widely apart the members of groups nearly united. Examples of this will be hereafter given. 486. The Natural System, on the other hand, aims to present an harmonious and consistent view of the Vegetable Kingdom, by associating into Orders those genera which agree in the most numerous and important characters, and which differ from others in the same. A table of the characters of these Orders would therefore resemble the Table of Contents of a well-arranged book ; giving at one glance to a person at all acquainted with the subject, an idea of the mode in which it is treated by the author, and of the relations which the several divisions of it had in his mind ; and enabling a person who is entering upon the study of it, to do so with the knowledge that he is not gleaning at random, as if he were reading through a Dictionary, but that every acquisition he makes of an individual part is something toward an acquaintance with the plan of the whole. One more illustration may set this matter in a still clearer light. The reader may be requested to consider this series of Treatises as completed according to the original plan ; and as consisting of a number of Volumes, each devoted to some particular Science, but all having a certain degree of connexion with each other. Each Volume consists of a series of Chapters, in which the sub- divisions of these Sciences are respectively treated of, and among which there is a still closer degree of connexion. Every chapter, again, is made up of a number of paragraphs, each intended to contain one or more important facts, the knowledge of which is in itself useful, but which can only be fully understood when read continuously with the preceding and following paragraphs. We shall further suppose that the subject of every paragraph IDEA OP NATURAL ARRANGEMENT. 333 could be concisely expressed by a single word. Now we will imagine these paragraphs, all printed on separate slips of paper, with their appropriate titles, to be given to a Man of Science, with a request that he would arrange them for publication. His first idea might, perhaps, be, to place them in alphabetical order, so as to form a kind of Dictionary ; this being the most easy method of fulfilling his task, and also having the advantage, when complete, of admitting very easy reference to any required subject. But what idea would the reader of such a volume gain, of the plan which the original Author had in his mind ? Or what connected and harmonious scheme of knowledge could he frame from them, unless he digested and arranged them in his own mind, in the manner in which we shall suppose our Man of Science to proceed to do ? He might commence in two ways ; either by separating the whole into heaps, according to the sub- jects to which they respectively refer, e. g. Mechanics, Chemistry, Geology, Botany, Zoology, &c., and then arranging these singly; or by endeavouring to join the separate paragraphs together, according to their obvious connection. He will pro- bably find a combination of these two methods the most advan- tageous ; and by a careful examination of each single paragraph, in its relations to the whole, he may at last succeed in producing a series of connected Treatises, methodically arranged according to their respective subjects, and regularly divided into chapters, very nearly, or even exactly, upon the plan of the original Author. Now the Alphabetical arrangement would bear a close parallel with the Linnaean system of Botanical classifica- tion; whilst the latter distribution, the one evidently most calculated to convey to the learner a connected rather than a desultory knowledge of the several objects of his pursuit, may not unaptly represent the Natural System. 487. It is by seeking for the latter only, that any of those general principles can ever be attained, which give their chief value to the facts of Science, and which lead us higher and higher in the contemplation of that Almighty Power and Bound- less Wisdom by which the Universe was framed ; for the Natural System would be but a Table of Contents of the Vegetable Kingdom, arranged on the plan of its Divine Author. In order 334 VALUE OF NATURAL SYSTEM. to attain it, the Botanist requires to become acquainted, not only with all the tribes of Vegetables at present existing on the surface of the globe, but with the forms and characters of those which have once existed ; since it cannot be doubted all these constituted parts of the one general scheme, without the knowledge of which it would be impossible to reconstruct it. Now it is well known to the Botanist, that a very large number of the species of Plants with which he is somewhat acquainted, have been so imperfectly examined and described, that their true place in the system cannot be determined ; and there is good reason to believe that there are many more of which he is totally ignorant. Here, therefore, are abundant causes for the imperfection of any natural system which can be at present framed ; and should these ever be removed by long-continued labour and research, there will yet remain the other causes, re- sulting from the impossibility of becoming fully acquainted with the characters of the races, which have existed in former periods of the earth's history, and which have been swept completely from its face. Of these, some remains are occasionally disco- vered, sufficiently perfect to excite the liveliest interest and curiosity, by showing that races once flourished, -which fill up many of the wide gaps existing between those with whose cha- racters we are now familiar, and which, if we knew more of them, would explain many things that are at present most perplexing. 488. Some of the strongest upholders of the Linnaean system are influenced by their veneration for its author ; whose fame, however, will rest on a foundation much more durable than this. It is not generally known that the advantages of the Natural method have never been more highly appreciated, than they were by Linnaeus himself. "When he framed an Artificial system for the convenient arrangement of plants, it was with the very pur- pose for which the temporary employment of it has been here recommended, namely, to facilitate that acquaintance with the Vegetable Kingdom, which must be gained before a Natural method can be framed. Linnaeus himself gave a sketch of the Natural System, explaining the principles upon which it might be expected to rest ; and he pronounced the investigation of the ATTEMPT BY LINNJEUS AT A NATURAL SYSTEM. 335 natural affinities to be the great object of his studies, and the most important part of the science. He considered the Artificial system as a temporary expedient, which, however necessary at that day, would inevitably give place to the system of nature, so soon as its fundamental principles should be discovered. The elucidation of the latter, he said, is the first and ultimate aim of Botanists; to this end the labour of the greatest Botanists should be diligently directed ; and the merest fragments of this system should be carefully studied. Though not then fully dis- covered, he spoke of the pursuit of it as held in high estimation by the wisest Botanists, and as being thought of little conse- quence only by the less learned. " For a long time," he adds, " I have laboured to establish it ; I have made many disco- veries, but have not been able to perfect it; yet while I live, I shall continue to labour for its completion. In the mean time, I have published what I have been able to discover ; and whoso- ever shall resolve the few plants which still remain, shall be my Magnus Apollo. Those are the greatest Botanists, who are able to correct, augment, and perfect this method ; which those who are unqualified should not attempt." Those therefore, who, priding themselves upon their being disciples of Linnaeus, con- tinue to employ his temporary and artificial system of classifica- tion, to the exclusion of one founded upon Natural principles, imagining that they are upheld by his authority, quite mistake the views of their great master, and sadly misrepresent his opinions. 489. The knowledge of the Vegetable Kingdom obtained by Linnaeus, however, was far too small in amount, to enable him to frame a Natural System upon sound principles. The number of species known to him was probably not an eighth part of those with which Botanists are now acquainted; and no arrangement, therefore, could be formed, which was not marked by many wide and unsightly gaps. Further, so little was at that time known of the internal arrangement of the organs of plants, that even the distinction between the two principal forms of structure in the stem, evident and well-marked as it now appears, was not then understood. Nevertheless, with that sagacity which so remarkably characterised him, Linnaeus suc- ceeded in grouping together genera into orders, which are even 336 PRINCIPLES OP NATURAL ARRANGEMENT. now regarded as. for the most part, very natural assemblages ; that is, as containing plants really allied to each other in their most important characters, and differing from those of other orders in the same. But of the best mode of arranging these orders he was necessarily ignorant, since the most important characters were not then understood. The great progress which has been made since his time, in the Structural and Physiolo- gical departments of Botanical Science, has done much to place Classification on a more certain basis ; yet there is still much wanting, before Botanists shall be generally agreed on the prin- ciples which shall regulate the division and subdivision of the Vegetable Kingdom. In the following outline, the object is less to give a bare sketch of the entire system, than to offer such a view of it, as may serve to show its nature. It is intended to describe most fully those Orders to which the greatest number of British Plants belong; and to state the relations which the species of most importance to man, whether as furnishing articles of food, valuable medicines, or materials for his various arts, bear to these. In so doing, it has been deemed advisable to adopt the Classification of De Candolie, being the one which is most in use at the present time ; and the principles upon which it is founded will, therefore, now be explained. 490. It may be remarked, however, in the first place, as a principle common to all Systems of Classification which profess to be Natural, that the different values which are attached to the various characters furnished by the several organs of plants, should be estimated by the degree in which they respectively indicate important similarities or differences si general conforma- tion. It often happens that attention to one or two characters may afford a considerable amount of knowledge of the whole ; because those characters are found to be inseparably connected with others. An instance of this lias been already given, in regard to the primary division between Exogens and Endogens (. 478) ; and it may be useful to illustrate it further by refer- ence to the Animal kingdom. If, for example, we meet witli an Animal covered with feathers, we at once know a great deal of its internal structure and economy. It is a Veriebraled animal, possessing a jointed back-bone and complete internal skeleton ; f O * PRINCIPLES OF NATURAL ARRANGEMENT. 337 it has all five senses ; its blood is red ; it breathes air ; its tem- perature is high ; its young are produced from eggs ; it walks upon two legs ; &c. &c. Here we are at once informed that this unknown animal possesses all the characters peculiar to the class of Birds ; since no other animals than Birds possess a covering of feathers, which is inseparably connected with the whole plan of their structure and economy. In the same manner, the clas- sification of the Mammalia (Quadrupeds) according to their teeth, proposed by Linnaeus, proves to be a very natural one, although founded upon a single set of characters ; because the form and number of the teeth vary with the nature of the food on which the animal is intended to live ; and to make use of this, a certain form of digestive apparatus is adapted ; as well as a certain kind of general structure, furnishing the instruments by which the food is obtained : so that these may be known to a great extent from the inspection of the teeth alone. In like manner the Botanist, whilst founding his arrangement upon the whole group of characters which each Plant exhibits, endeavours to select those, as marks for distinguishing the several divisions, which are at once easily recognised, and which serve as the best key (so to speak) to those which are seated within. Such cha- racters are Natural, then, in proportion as they indicate general conformity or difference of structure ; thus, the distribution of the veins of the leaves, a character easily recognised, will in general serve to distinguish Exogens and Dicotyledons from Endogens and Monocotyledons; and it is therefore a very natural character, serving as a key to all those which are indi- cated by these terms. On the other hand, the number of stamens and pistils in a flower is a purely artificial character, since it gives no further certain information of the general struc- ture of the plant. 491. Another general principle of Natural classification must next be pointed out. When a number of Plants or Animals are associated, on account of their general resemblance to each other, into a Natural group, it will be found that the characters in which they agree are presented by some members of the group much more prominently than by others ; and that in some they are occasionally so much wanting, that these can scarcely be 338 PRINCIPLES OF NATURAL ARRANGEMENT. regarded as connected with the rest ; yet they would riot seem to be more easily included in any other groups. Now those members of a natural group which most strikingly present a union of all the characters by which it is distinguished, are spoken of as its types ; and those in which these characters are less obvious are termed aberrant members of the group. It is by these, in fact, that natural groups are connected with one another ; for it will generally be found that in the aberrant members of one group, its characters become (as it were) gradually shaded off, until they almost blend with those of the next. To revert to an illustration formerly (. 18) employed; where the countries occupied by two nations are not separated by any marked natural boundary (as a broad river or high chain of mountains), the peculiar cha- racters of these nations, which may be regarded as most strongly exhibited in their respective chief towns, become gradually blended towards the border where they meet ; so that the tran- sition from one to the other is by no means so abrupt, as if the traveller were conveyed at once from the metropolis of each to that of the other. Every natural group, then, may be regarded as a sphere, surrounded by other spheres each representing another group, which touch it at certain points ; the type of each will occupy its centre ; and the aberrant members will be dis- posed in various positions around it, in proportion as they lose its peculiar characters and approach other groups. For example, the group of Lizards is intermediate between that of Serpents and that of Tortoises. There are some Lizards in which the body and tail are greatly lengthened, whilst the legs are shortened, so that the form of the Snake is approached ; and in the common Slow- worm or Blind- worm of this country, the external form is completely that of a Snake, whilst beneath the skin two pairs of small though perfectly-formed legs may be found on careful examination. This, then, is an aberrant form, situated just on the border of both groups, and scarcely having a certain claim to a place in either. On the other side, the Lizards are connected with the Tortoises by an American species commonly known under the name of the Alligator-Tortoise, or Snapping-Turtle, wnich may be considered as a Tortoise with a long Lizard-like neck, legs, and tail, or as a Lizard with a Turtle-shell on its back. PRINCIPLES OF NATURAL ARRANGEMENT. 339 The Lizards are connected, again, with Birds (to which they would not seem to have the slightest possible relation), by means of a very curious animal not now existing, which had the general structure of the Lizards ; but which had the fore-legs converted into wings like those of a Bird ; and which seems to have been covered with something intermediate between scales and feathers. Many similar instances will present themselves in the study of the Vegetable Kingdom. 492. Hence when it is stated that a Plant or Animal belongs to a particular group, it is by no means necessarily implied that it possesses all the characters which are considered as marking that group. Thus, to revert to an instance just now employed in illustration, the structure of the feathers, which are generally so characteristic of the class of Birds, is greatly modified in some of the species which approach nearest to other groups ; in the Emu, for example (one of the Ostrich tribe), the feathers are little else than stiff branching hairs ; and in the Penguin, those covering the fin-like wings resemble scales. So, again, in the first Natural group of plants which we shall consider, the Ra- nunculus or Crowfoot tribe, there are some species which have the parts of the flower arranged in threes^ as in Endogens ; yet they are not really such, for their stems are Exogenous, the veining of their leaves is netted, and their embryo is dicotyledo- nous. Again the common Arum maculatum (Cuckow-pint or Wake-robin) has reticulated leaves ; but it is not an Exogen, because its stem is Endogenous, and its embryo monocotyledonous. And the Pond-weed (Potamogeton) has the parts of its flowers arranged in fours ; yet it does not belong to Exogens, since its leaves are parallel- veined and its embryo is monocotyledonous. 493. In considering the value of the several characters afforded by the varieties in the structure of Plants, it will be convenient to follow the same order as that which has been adopted in describing that structure. The Elementary Tissues do not afford any means of distinction, except in regard to the primary divisions, the presence of Spiral Vessels being on the whole characteristic of Flowering Plants (which have been hence termed Vasculares) ; and their absence being nearly constant in 340 PRINCIPLES OP NATURAL ARRANGEMENT. Cryptogamia (which have been hence termed Cellular es). There are some of the inferior Phanerogamia, however, in which no spiral vessels can be detected ; and in the Ferns, which stand at the head of the Cryptogamia, modifications of them may be found. However, if on examining any portion of the fabric of an unknown plant, spiral vessels were distinctly seen, this might be regarded as sufficiently indicating that the specimen belonged to the higher of these two groups. The peculiarity of the woody fibre in the Coniferce and allied orders (. 78), together with the absence of the dotted-ducts or special sap vessels, is charac- teristic of that portion of the Phanerogamic division ; but excepting in this instance, no use can be made of the varieties of the elementary tissues, in defining the subdivisions of the classes of Plants. 494. The structure and mode of increase of the Stem afford, as already stated, the means of establishing the soundest division of the Phanerogamia : and the two groups of Exogens and Endogens are universally recognised as natural classes. Between these, however, there are several connecting links, some Exo- gens exhibiting in their stem no separation into annual layers, and some Endogens, presenting an approach to the Exogenous division of the kingdom. One small order (Calycanthece) is known by the presence of four incomplete centres of vegetation surrounding the principal one ; and the Passion-flower tribe are remarkable for having the stem almost cut into four quarters : whilst a square stem is universal in the Dead- Nettle tribe. In some orders, such as the Cactece (Prickly-Pear tribe) and Euphor- biacecB (Spurge Tribe), the quantity of cellular tissue usually so much predominates that the stems are soft and succulent ; but this is not always the case, some genera having stems of the ordinary character. No very positive characters can in general, therefore, be drawn from the structure of the stem, in dividing the classes into sub-classes and orders. Nor do the Roots afford any better guide ; since the modifications of form of which they are susceptible are very few, and they are by no means constant in particular groups. As a general rule, however, it may be observed that neither bulb nor rhizoma (. 149, 150) are found PRINCIPLES OF NATURAL ARRANGEMENT. 341 in Exogens, and that they are confined to a few orders among Endogens. 495. The Leaves are subject to considerable modifications, both in position, form, and structure, which are very useful in classification. The general differences among the leaves of Exo- gens, Endogens, and Acrogens, have already been several times adverted to. The relative position of the leaves, as whether alternate, opposite, or verticillate, is often a very important cha- racter ; but in regard to this, as well as to other characters, it often happens that it is of much greater value in some orders than it is in others. Thus in Lamiacea (Dead- Nettles) they are uniformly opposite : so that no plant can belong to the order, in which they are alternate or verticillate. In Urticacece (the Nettle tribe), on the other hand, they are constantly alternate ; so that no opposite-leaved plant can belong to the order. In this manner the common Dead-Netties and Stinging-Nettles may be at once known from each other. But in many others, one arrangement is prevalent, and yet the other sometimes occurs. The degree of division of the leaves, again, is subject to consi- derable uncertainty in many orders, from causes formerly adverted to (. 234 9) ; yet in others a constant form is maintained ; thus, leaves with teeth or jagged edges are never found in the order Cinchonaceee (from which the Peruvian Bark is supplied), and they are very rare in Endogens. The particular characters afforded by the veining of leaves are much more constant, as formerly shown (. 235), than those derived from their form ; and it is probable that, as they have only been recently attended to, much assistance will be obtained in classification from an increased knowledge of them. A character which would not at first sight appear of much importance, is afforded by the presence or absence of those little dots in the leaves, which are reservoirs of oily secretions ; yet these, being connected as it would seem with some important differences in the general economy, are extremely characteristic of certain natural orders, such as Myrta- cecK (the Myrtle tribe), and Aurantiacece (the Orange tribe), serving to distinguish all their members from those of other orders nearly allied to them. In other orders, however, there are some 342 PRINCIPLES OF NATURAL ARRANGEMENT. genera with, and others without these pellucid dots. The clear or milky character of the juices of the leaves and stalks, indicat- ing as it does the absence or presence of certain secretions which are characteristic of particular orders, will often prove of much use in distinguishing their members. At the base of the leaf- stalks are often found little leafy appendages (which are in fact leaves, in an imperfect state of development), termed Stipules ; the presence or absence of these frequently enables the Botanist to distinguish the plants of two allied orders, of which one pos- sesses them, whilst the other does not ; and certain peculiarities in them, which will be hereafter noticed, are occasionally very characteristic of particular groups. 496. Passing on to the Flowers, we first have to notice the characters afforded by the bracts ; these are seldom of any use in distinguishing orders, on account of their constant variation within the limits of each; but they are often valuable in separating genera and species. The calyx is used in a variety of ways to distinguish orders ; but the characters it affords are far from being of equal or uniform importance throughout. The number of sepals is sometimes a very useful and constant mark of a par- ticular order ; thus, in Cruciferae, the Cabbage and Turnip tribe, they are always four, and in Papaveracese, the Poppy tribe, always two : but in many orders it is extremely variable. The equal or differing size of the sepals is another character of great importance in some cases, but not to be regarded in others. Again, the union of the sepals by the adhesion of their edges, is a character to which great value may usually be attached ; when this adhesion unites all the sepals, the calyx is commonly said to be monosepalous (single-sepalled) ; but the term gamosepalous, expressing the union or adhesion of the sepals, is to be preferred. A still more important character is the degree of adhesion of the calyx to the organs it includes. Where it arises immediately from the disk or expanded top of the flower-stalk, and where the corolla, stamens, and pistil are quite distinct from it, arising by themselves from the disk (as in Fig. 127), the calyx is said to be inferior to the ovary, or non-adherent to it. But where the calyx seems to spring from the top of the ovary or seed-vessel, PRINCIPLES OP NATURAL ARRANGEMENT. 343 instead of beneath it (as in Fig. 129), it is called superior ; this conformation is due to the adhesion of the calyx to the wall of the ovarium, so that it forms a tube completely enclosing it, as in the Rose, Apple, &c. In some plants the calyx is altogether absent ; and then the general rule is that the corolla is likewise deficient. Such plants are said to be Achlamydeous, the essential parts of their flowers being destitute of envelope. In the Com- posite, however, which possess a corolla, the calyx is present in an undeveloped form, constituting the down or pappus, which surrounds the bottom of the corolla, and is attached to the top of the seed-vessel, as in the Dandelion. 497. In regard to the number and regularity of the parts of the corolla, nearly the same may be said as of the calyx. These characters are valuable in some instances and not in others. The separation or adhesion of the petals, constituting what is com- monly known as the polypetalous or monopetalous corolla, is often a character of first-rate importance, as will presently appear. Still, from the cause formerly mentioned, (. 456) it is liable to some uncertainty, and must not, therefore, be trusted too implicitly. Sometimes no corolla is to be found, the calyx still being present ; and the plant is then said to be apetalous (destitute of petals), or Monochlamydeous (having but one enve- lope). This is a character, however, on which great reliance cannot be placed; since apetalous genera frequently present them- selves, in orders which usually possess complete flowers, an occurrence which is less common amongst monopetalous Exogens, than among those which have separate petals, so that the character is of more value in the former than in the latter. 498. When our attention is directed to the more essential parts of the flowering system, the stamens and pistil, we meet with some characters on which more constant reliance can be placed ; but these are not among the most obvious, such as the inexperienced Botanist would first attend to. For example, the number of stamens is a character to which little importance can be attached ; since this is liable to vary extremely among the genera of almost every order, in many cases among the species of the same genus, not unfrequently, among individuals 344 CHARACTERS OP NATURAL SYSTEM. of the same species, and even in different flowers on the same plant. Yet there are particular orders, in which the number of stamens is very constant throughout, and is very characteristic of them. The most important characters afforded by the stamens, are drawn from their mode of origin from the lower part of the flower. They may arise, like the sepals and petals, from the disk, beneath the ovary ; in this case they are said to be hypogynous (this term designating their origin from beneath the female part of the flower). A sectional view of a flower con- structed upon this plan is shown in Fig. 127; the sepals of the calyx, the petals of the corolla, the stamens, and the pistil, are there shown to be all separately implanted on the disk. But it may happen that the sepals and stamens arise together, (these parts being opposite in a regular flower, whilst the petals alternate with them so as not to prevent their adhesion, . 463), and that they ad- here for a part of their length, so that the stamens appear to arise from the calyx, and come away with it when it is detached ; in this case, or when they adhere in a similar manner to the petals, they are said to be perigynous, having their origin around the female organ. A plan of such a structure is shown in Fig. 128. Lastly, when the calyx embraces the ovarium, it also closely envelops the stamens, which are not freed from it except at the top of the seed-vessel ; in this case, the stamens, appearing to arise from the top of the ovarium, are said to be epigynous, being seated FIG. 128. FIG. 129. CHARACTERS OF NATURAL SYSTEM. 345 upon the female organ. This mode of conformation is illustrated by Fig. 129, which also explains what was meant by a superior calyx (. 496). Peculiarities in the mode in which the anthers open to disperse the pollen are sometimes characteristic of particular orders; thus the Berberry and Laurel tribes have anthers bursting by valves ; and the Heaths have anthers opening by pores (. 433). But such peculiarities are found in other genera, amongst orders which do not possess them ; and they must not, therefore, be implicitly relied on. 499. Of all natural characters, those furnished by the struc- ture of the central parts of the flower are perhaps subject to the fewest exceptions; yet these are not such as are the most evident to the ordinary observer. On the number of styles, as already stated, little reliance can be placed for the establishment of important distinctions; but as it is less liable to vary than is that of the stamens, it may often be useful in the separation of genera. A much more decisive character is afforded by the degree of adhesion among the carpels ; when they remain distinct from each other, the ovary is said to be apocarpous (carpels apart); and when they are compactly united, it is termed syncarpous (carpels together). There are few natural orders in which one or other of these conditions does not prevail, to the entire exclusion of the other ; so that plants which bear a strong resemblance in general aspect, but differ in this, may be at once referred to their proper groups. The position of the ovary in respect to the calyx has been already adverted to ; this character is generally expressed by the terms inferior or superior ovary. The presence or absence of partitions in the ovaries, is a very important distinction. An ovary may be one-celled, because it consists of but a single carpel; or, being syncarpous, it may contain an undivided cavity, from the obliteration of the par- titions, or dissepiments, originally formed by the walls of the several adhering carpels. In this case the attachment of the ovules, or placenta, is either central, the ovules being clustered around a central column (as in Fig. 83, . 434), or parietal, where they are attached to the outer wall (as in Fig. 84). Varieties of structure of this nature are very important in dis- 346 CHARACTERS OP NATURAL SYSTEM. tingtrishing orders. A peculiar enlargement of the receptacle, which sometimes expands between the bases of the carpels so as to separate them more or less completely (. 470), as in the Strawberry, is often very characteristic of particular orders. The ripened ovary or fruit exhibits numerous and remarkable differences in its form, substance, and mode of dehiscence (or its manner of bursting when ripe); but these do not usually receive much attention from Botanists ; since although there are a few orders which are characterized by a particular kind of fruit, most others present numerous varieties among their different genera. 500. Many valuable characters are drawn from the seed, both in its early and mature conditions. The number of ovules, that is to say, whether they are definite or indefinite, is frequently an important difference ; still in some orders, there are genera nearly allied, in one of which the number is definite, whilst it is indefinite in the other. The position of the ovules is more essential than their number; the chief distinctions are between those which, rising upright from the base of the cavity, are termed erect ; and those which, hanging from its top, are called pendulous. Between these two conditions, however, there are other intermediate ones. Such a difference in the position of the ovules often serves to mark a distinct line of separation between the plants of two groups that are otherwise nearly allied. In the perfect seed, the number of cotyledons is a character of primary importance, for distinguishing the two great classes of Phanerogamia, as already several times stated. Even this, how- ever, is subject to occasional exceptions; for there are Endogenous Plants with two cotyledons, and some Exogens with only one, or even none ; whilst again, some Exogens have several. As a means of distinguishing orders, the presence or absence of a separate albumen (. 439) is a character of great value, especially when the embryo bears a very small proportion to it in amount, as in the orders we shall first have to consider. Where, however, the embryo and albumen are nearly equal in size, the character is of less importance ; so that it is not uncommon to meet, in the same order, with some genera, of which the embryo alone fills the seed, and with others in which a part is occupied by albumen ; CHARACTERS OP NATURAL SYSTEM. 347 whilst in the orders especially characterized by it, there is pro- bably not a single genus in which it is absent. It must be remembered that albumen exists in all seeds at an early period of their formation; and that the subsequent difference will depend upon the degree in which it is absorbed by the embryo. 501. The student, who has given attention to the preceding statements, is not unlikely to feel some perplexity, on account of the constant uncertainty which has been stated to attend the value of the several characters that have been enumerated. But as he proceeds further, he will find that this uncertainty is greater in appearance than in reality; and that it necessarily results from the properties of a Natural Group, as already described. In dividing the Vegetable Kingdom on an Artificial Method, it seems very easy to lay down a small number of characters as the standard ; and to bring together, or to separate, Plants, according to their conformity or variety in these. But, as has been, already shown, when we come to apply this plan, numerous difficulties are met with, in consequence of the differences which are of constant occurrence, among plants belonging to the same genus or even to the same species (. 481); so that even here, the Botanist must be guided by general resemblance. Now, although it is quite true that no single characters, when traced throughout the Vegetable scale, can be relied on, as indicating the Natural Affinities of plants, yet experienced Botanists have little difficulty in defining each order, by a certain combination of characters which are peculiar to it; and not unfrequently, the plants belonging to one order may be separated from those of all other groups, by some evident and well-marked peculiarity. 502. On the foregoing principles, the class of EXOGENS is divided by De Candolle in the following manner. The first group consists of those, of which the Flowers possess both calyx and corolla, and in which the petals of the latter aie distinct, and which are therefore Polypetalous. This group is divided into two Sub-classes, according to the mode of insertion of the stamens. 348 DE CANDOLLE'S CLASSIFICATION. Sub-class 1. Thalamiflorce. Polypetalous Exogens, in which the stamens arise from the disk, that is, are hypogynous. Some- times the stamens adhere slightly to the sides of the ovary, but they are never epigynous, nor perigynous (. 498). Sub-class 2. Calyciflorce. Polypetalous Exogens, in which the stamens arise from the calyx or corolla, that is, are perigynous. In the next Sub-class, the flowers, still possessing both calyx and corolla, have the latter formed of united petals, or are Monopetalous. In this division, the position of the stamens is not regarded as a primary character. Sub-class 3. Corolliflorcc. Monopetalous Exogens. In the lowest group, the corolla is always absent, making the flower Apetalous ; and the calyx is not uniformly present. This character is regarded as sufficiently marking the group. Sub-class 4. Monochlamydece, Apetalous Exogens. The object of this classification is to proceed from what are considered the most perfectly- organised Exogens, to those which are least so. Thus all the parts are present and distinct from each other in Thalamiflorce ; other things remaining the same, the stamens adhere to the perianth in Calyciftorce ; the petals join together in Corolliflorce ; and in Monochlamydece first the corolla disappears, and then, among the most imperfect orders the calyx ceases to be developed. 503. The class of ENDOGENS is not divided, by De Candolle, into any Sub-classes. It will, however, be convenient to con- sider their orders as characterised by the completeness or incom- pleteness of their flowers. The Complete Endogens may be again sub-divided into those with a superior^ and those with an inferior ovarium. The orders having Incomplete flowers are separated into those, in which a cluster of flowers is inclosed in a single large bract, termed a Spathe, which is frequently coloured (as in the Arum tribe); and those in which the perianth of each flower is replaced by scale-like bracts, as in the Grasses. ORDER RANUNCULACE.E. 349 CLASS I. EXOGENS. SUB-CLASS I. THALAMIFLOR.E. Order RANUNCULACE^K, or Crowfoot Tribe. 504. If we examine the btiacture of the flower of the com- mon Crowfoot or Buttercup, so abundant in our meadows as to be everywhere easily found, we shall observe the following to be the plan of its formation. Beneath the yellow petals, there may be seen Jive small greenish-yel- low leaflets ; these are the sepals of the calyx (. 455): they fall off shortly after the flower opens. Within these are five other leafy organs, of a bright yellow colour on both sides, which give to the Buttercup its gay and glittering appearance ; they stand up and form a little cup, in the bot- tom of which the other parts of the flower are curiously arranged ; these are the petals of the corolla. At the base of each will be seen, on the inside, a little scale, from which honey exudes. Within the corolla are found a large number of stamens, with very short filaments ; which, like the sepals and petals, are all separately im- planted on the receptacle. Almost buried within the stamens, and occu- pying the centre of the flower, are a number of little green grains, collected as it were in a heap, and seated upon a small elevation of the receptacle, into which the stamens, petals, and sepals are all separately inserted. They are too small to be seen readily without a magnify ing-glass ; but when enlarged in that way, they are observed to be rounded at the bottom, and con- tracted into a sort of' short bent horn at the top. Each of these is a single carpel; the horn-like projection is the style whicn it Fre. 130. FLOWER-STALK OF MEA- DOW CROWFOOT ; on the right, an open flower and dry fruit ; on the left, expanding buds; a, a, bracts; b, calyx. 350 ORDER RANDNCULACE^E. bears ; and the tip of this, which is rather more shining, and somewhat wider than the style it- self, is the stigma (.434). Every one of these car- pels contains a single ovule or young seed ; it re- quires, however, some dexterity to make its contents apparent. The FIG. 131. PARTS OF THB FKNVKR OF THE COMMON RANUN- ovule when YOUng, TULUS, OR BUTTERCUP. 1, one of the petals, with the scale :it the bottom on the inner side ; 2, one of the carpels, show- Occupies but a ing a, the ovary, b, the style, and c, the stigma: 3, section of 0.,]] -n nr f n f tliP the unripe carpel, showing rf, the ovule within it ; 4, section of the matu;e carpel filled with the seed a, the embryo, cavity of the car- b, the albumen.; 5, the carpels and some of the stamens, , , implanted on the receptacle. P el > m time, how- ever, it increases, so as to fill it completely. After the calyx, corolla, and stamens have fallen off, the cluster of carpels remains and ripens into the fruit of the plant. They undergo little change of form, though increasing in size ; but they become dry, brown, and hard, re- sembling seeds. Though they are ordinarily taken for such, they are, as just shown, the seed-vessels, each containing but one seed. When this is the case, as it is in Corn, the carpels are termed grains. If the grain be cut through, nothing but a solid mass of white flesh will be met with, of which all the portions seem alike ; unless the section have passed exactly through the centre, when there may be distinguished, near the base of the seed, a minute oval body, which may be taken out of the flesh upon the point of a needle. This oval body is the embryo of the young plant, with its two cotyledons ; and it is embedded in a separate albumen (. 439). 505. On looking at other parts of the plant, it will be observed that the leaves are dark-green ; and that they are very much divided by deep indentations. It will further be re- ORDER RANUNCULACEJ2. 351 marked that their form is simpler at the upper part of the stem than near the root ; the lobes or chief divisions being narrow, and not themselves divided, in the former case ; whilst in the latter they are more expanded, and their edges are deeply cleft. At the bottom of the flower-stalk may be observed a couple of small leafy bodies, which are the bracts (. 457). These, as formerly stated, are intermediate in character between the true leaves and the leafy portions of the flower ; and of this fact the species under observation affords a remarkable illustration. Two specimens, pulled at random from the nearest field, are now before the writer ; in one the bracts are simple in their form, like the sepals of the calyx ; in the other they are cleft into three lobes, and more resemble ordinary leaves. 506. Now the foregoing characters are those, by which the order RANUNCULACE.E is separated from other tribes ; but they are not all presented by every plant which, on account of its general resemblance, is placed in the same group with the com- mon Crowfoot. For example, there are some which have 3 or 6 sepals in their calyx, instead of 5, the regular number. The petals, again, are sometimes more numerous than 5, and some- times altogether wanting. The number of stamens is quite indefinite. That of the styles is also variable, since the styles of the different carpels may unite into a single one, or into a small number, or may remain (as in the common Ranunculus) entirely distinct. The number of seeds in each carpel is not restricted to one. It will be asked then, what are the essential characters by which this natural group is marked ? They are simply these. The stamens are numerous, and arise from the disk beneath the carpels ; and the carpels are themselves distinct.* The struc- ture of the other parts of the flower may or may not be con- formable to that of the common Ranunculus ; and it is in fact by the minor variations, that the order is subdivided into genera. The greatest apparent resemblance of the flowers of this group, * This last character is occasionally subject to exception, the carpels being more or less united in some species ; but other characters of resemblance then come to the assistance of the Botanist, and enable him to determine the place of these epecies in the order. 352 ORDER RANUNCULACE^:. is to those of Rosacese ; but they may be at once distinguished by the position of the stamens, which in the latter, are adherent to the calyx, instead of arising at once from the receptacle. 507. All the plants agreeing in these general characters, also agree in their properties; for their juice is constantly acrid and nauseous, though in a degree which varies in the different species. In some of them, there is also a certain amount of a narcotic principle. These properties cause several species to be useful in medicine, as will be presently noticed ; but they prevent them from being of much utility as food, causing them to be usually rejected by cattle, which eagerly devour the harmless plants around. The Ranunculaceae further agree in being either her- baceous or shrubby plants; never rising to the dignity of standard trees. 508. Of the Ranunculus itself, many species are natives of Britain. Among the commonest are the R. acris of our mea- dows, and the R. sceleratus, or Celery-leaved Crowfoot, of the sides of pools and ditches. Both these derive their specific names from the acridity of their juices, which excoriate the skin, and even form ulcers that are difficult to heal ; and the simply holding specimens in the hand for a short time, will sometimes inflame its surface. The R. aquatilis, or Water-Crowfoot, is one of the least virulent of the order ; and in some parts of the country, where it abounds, it is employed by cottagers as a fodder for cows and even horses. There is a curious distinction between the leaves of this species, some being submersed beneath the water in which the plant grows, whilst others float upon its surface; the former are subdivided into a large number of rounded hair-like filaments ; whilst the latter are but little separated into lobes. Some foreign species of Ranunculus are much cultivated in gardens, on account of the beauty of their flowers, which have a tendency to become double, that is, to have one or more additional whorls of petals developed within the ordinary corolla, at the expense of a corresponding number of stamens. 509. To this group also belong the well-known Anemonies, whose flowers are so attractive with their white, blue, or purple CROWFOOT TRIBE. 353 petals, on wooded banks. In these the petals and sepals cannot be distinguished, the whole perianth being coloured alike. They exhibit a remarkable tendency to variation in the character of the flower, usually depending upon the amount of nutriment which the plant receives (. 461). Sometimes the sepals revert to the form of ordinary leaves, whilst the petals exhibit a greenish tinge, and the stamens of the outer row approach the petals in character. The transformation may extend farther inwards, the petals becoming quite green, the outer stamens resembling ordinary petals, and the inner ones presenting an approach to the same form. Every shade and variety of metamorphosis may be met with, until all the parts of the flower, carpels as well as stamens, are found to have been transformed into leaves, of which the inner ones are most simple, whilst the several whorls change in their character towards the form of the exterior one, which corresponds with that of the ordinary leaves of the plant. When the flower of the Anemone has dropped off, there is seen in its place a little tuft of feathery tails or oval woolly heads, in place of the clusters of grains which are found in the Ranunculus. These tails are nothing but the styles of the car- pels, grown large and hairy ; they probably serve the purpose of wings by the action of the wind upon which, the carpels con- taining the seed are dispersed. The Hepaticas differ little from Anemonies ; they were once in repute for their supposed medi- cinal virtues in diseases of the liver ; but they are now esteemed merely as ornamental garden plants, and it is curious that they may often be seen to thrive when neglected in a cottage garden, whilst they perish under greater care, as if they were created specially for the pleasure of the poor. 510. Another subdivision of the order is that which con- tains the Clematis, a genus of climbing plants, of which the species native to Britain is known under the name of Traveller's Joy ; whilst another, which is much cultivated in gardens, is commonly called Virgin's Bower. These are almost the only plants of the order which form woody stems ; they grow in hedges and against walls, their petioles being prolonged as ten- drils ; and, in spite of the acridity of their juices, their flowers are mostly fragrant. 354 ORDER RANUNCULACE.E. 511. A group which departs more widely from the ordinary characters of the tribe, is that which includes the Hellebores and their allies. The irregularity of these chiefly lies in the petals and stamens. In the Trollius, or globe-flower, which inhabits moist mountain pastures in this country, and is conspicuous with its large handsome flowers, the petals are contracted into little linear bodies, scarcely exceeding the stamens in size ; and it is to the petalline character of the sepals, which are usually about 15 in number, that their showy aspect is due. The Caltha, or Marsh Marigold, which grows in large tufts in wet meadows and by the sides of ditches, has no petals at all. The common Green Hellebore^ abundant in woods, thickets, and hedges, espe- cially in calcareous soils, -and the Stinking Hellebore, a bushy plant of similar habits, are easily known by their large greenish - yellow sepals, and their small tubular petals. A foreign species of Hellebore is cultivated in our gardens under the name of Christmas Rose ; here the substitution of petals for stamens, and the general aspect of the plant, make the resemblance to the order Rosacese very striking ; but the flowers are easily distin- guished by the characters already mentioned. The Hellebores were formerly in great repute for their medicinal virtues, espe- cially in the cure of mental derangement. The Black Hellebore of the ancients grew plentifully near Anticyra, a city of Phocis in Greece ; whence arose the proverb, applied to any one who acted in an absurd manner, " Naviget Anticyram," " Let him sail to Anticyra." They are now disused, however, as their purgative properties are so violent, as to render their employ- ment dangerous. The Aquilegia or Columbine, and Delphinium^ or Larkspur, belong to this group ; a species of each genus is a native of Britain; but others with much more showy flowers, obtained from' abroad, are cultivated in our gardens. They are both distinguished by great irregularity in the petals, these having long tubular spurs, of which the small scale at the bot- tom of the petal of the Ranunculus may be considered as the rudiment; and in the latter, the several petals differ inform, two only being spurred ; and one of the sepals of the calyx has a horn, in which the two spurs are hidden. Both these plants CROWFOOT TRIBE. 355 have been employed in medicine, but are now disused for the same reason as the Hellebores. 512. The most irregular of all the flowers we have to notice in this order, is that of the common Aconite, ordinarily known as Wolf's-bane or Monk's-hood, which is occasionally found wild in this country, although it has probably escaped from gardens, in which it is much cultivated, on account of its showy aspect. The sepals of this flower are purple-coloured, like petals ; and one of the five is very large, resembling a sort of helmet, and overshadowing all the other parts of the flower. Of the petals only two are developed ; and these are so much changed in form, that they would be scarcely recognised as such ; they are two fleshy bodies, mounted upon long stalks, projecting into the hollow of the helmet-shaped sepal. Three other abortive petals may generally be detected as little scales, when the calyx has been removed. The leaves and roots of the Aconite contain more of the narcotic principle than those of other plants of this order : if the former be chewed for a few minutes, a curious tingling sensation is experienced in the lips, showing that the nervous system is immediately affected. The extract made from them has been used with good effect in many nervous diseases ; but in making it great precaution is required, as its properties are destroyed by a very moderate degree of heat. In this respect, the rest of the tribe resemble it ; and the leaves of many, which would be very poisonous when fresh, may be ren- dered wholesome food for cattle by drying them with moderate warmth. 513. The Pceonies, much cultivated in our gardens, on account of their showy flowers, are generally considered as belonging to the Crowfoot tribe, although differing from it in some important particulars. Of these we may notice that the calyx, instead of dropping off at an early period, as in most of the order, lasts as long as the flower-stalk itself ; and the carpels, instead of being numerous, are diminished to 5 or even 2, containing, however, many seeds, and having an elongated form. In the species which is wild in Britain (though only met with in one or two localities) there is only a single row of petals ; but, as in the 356 ALLIES OP RANUNCULACE^E. MAGNOLIA TRIBE. Anemone and many plants of this tribe, the cultivated species have the number very much increased, so that the stamens may be even entirely replaced by them, and the outer ones then approach the sepals in character. The gradual transition in the form of the leafy parts, between the lower portion of the plant, and the centre of the flower, which may readily be observed in the common Garden Paeony, has been already noticed (.457-9). 514. As a considerable number of stamens is characteristic of the plants of the order of Ranunculacese, when not modified by cultivation, they mostly belong to the Linnasan class POLY- ANDRIA. The orders of this class under which they are included, are different, according to the number of styles which are deve- loped. One British genus (Actaa, Bane-berry) allied to the Pseonies, has but a single carpel and style, and therefore belongs to the order Monogynia, where it is associated with the plants of the Poppy tribe. The Paaonies, Hellebores, Larkspurs, Co- lumbines, and Aconites, have styles varying in number from 2 to 6, and are placed in the order Pentagynia (ym?-styled), -an example of the very loose and indefinite application of terms in this kind of classification. The only British genus associated with them in this order is the Stratiotes or Water- Soldier, so named from its sword-shaped leaves, which is an Endogenous plant belonging to the Frog-bit tribe. The Ranunculus, Ane- mone, Clematis, Marsh-Marigold, and their allies, having a large number of styles, are placed together in the order Polygyma, which contains no other British genus. 515. Succeeding the Ranunculaceaa in a natural arrange- ment, is an order apparently very different from it, of which a brief mention will suflice. This is the splendid Magnolia tribe, of which no species are natives of this country, but of which more than one has been introduced into gardens ; and, although natives of warm climates, they thrive well in the milder parts of Britain, if protected by a wall. The Magnolias are for the most part large and beautiful trees, sometimes attaining the height of 90 feet, and surpassing almost all the other denizens of MAGNOLIA TRIBE. 357 the forest in their superb foliage, (the leaves sometimes attaining the length of three feet), and in their magnificent goblet-shaped flowers, that look as if they were chiselled out of alabaster. The East Indian species are most remarkable for the perfume they diffuse. It would scarcely be supposed, that these princes of the Vegetable kingdom should be allied to the humble Crowfoots we have been just considering ; and yet the structure of their flowers shows them to be so. The Magnolia has a calyx of three small sepals, and a corolla of six petals ; these numbers, though varied in the different genera, are usually multiples of three. The stamens are numerous, and arise immediately from the receptacle. In the centre of the flower there are a large number of carpels, each containing a distinct cell, and terminated by a narrow thread-shaped stigma. In no essential point, then, does the flower of the Magnolia, as yet described, differ from that of the Ranunculacese ; there is this important variation, however, that the carpels of the former grow together in some degree, so that the fruit, instead of consisting of a cluster of grains, as in most of the Ranunculacece, appears as a solid cone. 516. There is a more important difference, however, in the leafy parts of the tree. There may be found in many plants, at the base of each leaf-stalk, a pair of small leafy bodies, which are called stipules^ and which are to the leaves very much what the bracts are to the flowers. In the Magnolia the stipules are large, and perform an important function, to which there is nothing analogous in the Ranunculaceae. Each of its branches is ter- minated by a little horn-like projection, springing from the base of the last leaf ; this horn is a pair of stipules, rolled together for the protection of the next leaf that is to be unfolded. That and the next leaf has a similar pair of stipules, which roll up over the still younger leaf lying at the base of its yet undeve- loped petiole ; and if the horn be cut through, several generations of leaves will be found thus enfolded one within the other. This is a characteristic peculiarity of the Magnolia tribe ; and it has an interesting relation with the circumstances of its growth ; for the bud is peculiarly tender, and requires to be protected from 358 CUSTARD-APPLE TREE. COCCULUS TRIBE. cold and accidents. In other plants we meet with different provisions for this purpose ; in this instance the stipules are made to perform the business of protection. The different parts of the plant, in all the known species of this order, contain, in greater or less degree, a bitter principle, which has been successfully used in medicine as a tonic, particularly in North America, where this tribe most abounds ; but it is not employed in this country. 517. Allied to the Magnolia tribe is the order ANONACEJE, or Custard- Apple tribe, which is confined to tropical climates ; it FIG. 1.32. ANONA SQUAMOSA, OR CUSTARD- APPL E : a, the flower; b, fruit; c, the same in section, showing the position of the seeds ; d, seed ; e, section of the seed. is best distinguished by the structure of its seed, the innermost coat of which forms several plaits or folds, that enter the albumen. The Custard- Apple of the East and West Indies is a refreshing fruit, combining an agreeable acidity with sweetness; other species of the order have aromatic properties. 518. Another tropical order, intermediate between this and the one to be next mentioned, is that of MENISPERMACE^E, the Cocculus tribe. These are twining shrubby plants, chiefly dis- tinguished by the deficiency of parts in their flowers, which are constantly unisexual (the stamens and pistils never being deve- loped in the same flower), and are sometimes dioecious (. 435). The number of carpels varies considerably, as does also their degree of adhesion ; so that it is altogether difficult to charac- terise the order, the different genera of which, however, corres- pond remarkably in the medicinal characters that render it chiefly interesting. The root is bitter and aromatic ; that com- monly known as Columbo root is much employed in this country BERBERRY TRIBE. 359 as a tonic and stomachic ; and that of other species is used for the same purpose, in the countries of which they are respectively natives. On the other hand, the seeds of most of them are narcotic, in various degrees. The drug named Cocculus Indicus is the seed of an Indian Menispermum ; it has been much em- ployed by brewers in this country to heighten the intoxicating properties of their malt liquor, so that it is now illegal for a brewer even to have the article in his possession ; it has also been employed by poachers to capture fish, which it causes to become powerless and to float on the water. A large quantity is im- ported into this country, in spite of the illicit nature of the uses to which alone it can be applied. 519. Another interesting order, possessing the same general structure, but having very different properties, is that of BER- BERIDE.E, represented in Britain by the common Berberry, a shrubby plant, frequent in hedges and plantations, and well known from the bunches of red succulent acid fruit which it bears. The branches of this bush are covered with sharp spines, in sets of three or more ; and from the base of each set the leaves arise. Now these spines are nothing else than the hardened veins of the first-produced leaves of each bud, between which the fleshy tissue is not developed (. 236); and this will become evident, on looking at a very vigorous shoot of the plant, which will exhibit at some points the space nearly filled up with parenchyma; at others partly so ; and at others, the spines entirely bare. This is not, however, an universal character of the order ; but it is one which marks the common species before us, as well as many others. The flowers present several interesting peculiarities. Their parts are generally arranged in threes, the number of sepals, petals, and stamens, being six in the common Berberry. The anthers open by valves, in the manner formerly described (. 432), which character is sufficiently distinctive of this order ; and the stamens possess a curious irritability, which also has been already noticed (. 421). The position of the stamens is peculiar, being opposite to the petals, a character which the Menispermeae share with them (. 463 5). The ovary consists of only a single carpel, containing from one to three seeds ; and it is this 360 ORDER NYMPH ACE^. which in time changes to the oblong scarlet berry of the common Berberry, which genus of course belongs to the Linneean class FIG. 133. EPIMEDIUM ALPTNUM, AND BERBERIS SIBEHICA. HEXANDRIA, and order Monoggnia. The British Epimedmm or Barren- wort, however, possessing only four stamens, is referred to the class TETRANDRIA ; but there is a North American species which conforms to the general type in possessing six stamens. 520. Another order which may be briefly noticed, is that of NYMPHACE^E, the Water-Lily tribe ; the two common species of which, the White and Yellow Water- Lily (belonging, however, to different genera) are sufficiently well known. Much con- troversy has taken place, as to whether this order is to be ranked amon^ Exogens or Endogens, as its herbaceous stem does not afford the means of satisfactory determination, and the structure of its leaves is such as might agree with either group. Here, however, the number of the parts of the flower, which are arranged in fives, affords important assistance ; and, in spite of some general resemblance which the Water-Lilies bear to the Water-Plantains, this fact would lead us to rank the order with Exogens, of which the number five is characteristic, whilst it never presents itself in Endogens. The structure of the seed confirms this conclusion ; for the embryo is a little dicotyledonous body, enclosed in a peculiar bag which separates it from the ORDER NYMPH ACE^l. 361 albumen ; this bag has been mistaken for a cotyledon, wrapping round the embryo, whose real cotyledons were overlooked ; so that the seed has been erroneously considered monocotyledonous. 521. The flower of the White "Water- Lily offers many points of interest. It consists of about twenty-five thickish oblong leaves of a white colour, arranged in whorls of five each ; the five external ones are green at the back, and may be regarded as forming the calyx; towards the interior of the flower, the petals gradually become smaller, and are tipped with yellow at their points, which are thickened. From these a very gradual transi- tion takes place towards the form of the stamen, as heretofore described (. 460) ; and the inner rows of stamens (which are usually all together about 50 in number) shorten and produce less perfect anthers. The ovary has the lower floral leaves adherent to it, so that the stamens appear to arise from just below the stigmas. It consists of ten or eleven distinct carpels, which adhere closely together ; their several walls still forming com- plete partitions in the ovary, each chamber or cell of which contains a large number of ovules. The ovary is surmounted by a number of orange-coloured stigmas, radiating from the centre, very much as in the Poppy ; but as they are all united at the centre, they are considered as forming but a single pistil ; and the plants of this order are therefore arranged, with those of the Poppy tribe, in the Linnaean class and order POLYANDRIA Mono- gynia. They agree in possessing some bitterness and astringency in their juices ; and also in being all floating plants. They are most abundant in the northern hemisphere, and have been said to be entirely absent from South America; but a species has been recently discovered there, which in size and splendour far surpasses all others. This is the Victoria reyalis ; of which the leaf is from 5 to 6 feet in diameter, salver-shaped, with a rim rising from its edge, of from 3 to 5 inches high, green inside and crimson on the exterior. The flower is of proportional dimen- sions, the expanded calyx sometimes attaining a diameter of 23 inches ; this contains several hundred petals, which are at first of a white hue, passing gradually towards pink in the centre, and those nearest it becoming pink throughout. As in the common FIG. 134. WATER-LILY TRIBE. White Water- Lily, the petals gradually change into stamens towards the interior of the flower; those next the calyx are fleshy and contain air-cells, which must contribute towards the buoyancy of the flower. Their sweet scent enhances its beauty. 522. The small Order FUMARIACE^, or Fumitory tribe, is chiefly deserving of notice, on account of its containing some British species, of which one is among our most common wild plants. $ff(Q $QL /S #S SIB '^ Their flowers are remarkable for yl JL Y*/f*r~\\\ only possessing two sepals in the !A\( 1// \\* * f. calyx, and four petals which are parallel to each other, the outer one having a little cavity or pocket near its base ; they are also remarkable for never completely unfolding, the inner petals remaining adher- ent at the top, so as to enclose the anthers and stigma. The stamens are six, and are united into two parcels, whence the family belongs to the Linnaean class DIA- DELPHIA. The ovarium contains but a single cell, being formed by only one carpel, or by the union of two without a partition ; and the ovules, which are sometimes single and sometimes numerous, are attached in a horizontal direc- tion. This order, which is prin- cipally found in the temperate latitudes of the northern hemi- sphere, is characterised by no pro- perties worthy of special notice. Fro. 135. FUSTAFUA LLTKA. 363 Order PAP AVERAGES or Poppy Tribe. 523. The common British species of this order are well known as the plague of the farmer, coming up as rank weeds in his corn-field ; and another species is important as yield- ing a product, which, used with discretion, is one of the most valuable medicines we possess, but which, by the folly of Man, has become the bane of mil- lions. If any of the common species of Poppy be examined, they will be found to bear a considerable general resem- blance to the Ranunculacese. The leaves are much divided, and the stamens are numerous, arising from under the carpels. Unlike the Crowfoot and its allies, however, the carpels are no t separate from One another, but are united together into no styles are present ; and the stigmas FIG. 136.-LEAF AND FLOWER OF THE NAKED-STALKED POPPY, exhibiting the four petals, numerous stamens, and single ovary. a single ovarium ; are elevated hairy lines, which spread equally from the top of the ovary, forming a sort of star-like crown. If the ovary be open- ed, it will be found tO Contain but One ppll or cavitv * _ * ' several little par- titions, however, project from the sides towards the centre ; and FlG . 137. PARTS OF THE FLOWS* ENLARGED ; 1, a flower ^ud, Bowing the two sepals which enclose it ; 2, the ovary with its radiating stigmas ; 3, the ovary cut open. BB'2 364 PAPAVERACEJE, OR POPPY TRIBE. these are covered with numerous and very small ovules or young seeds. The common Poppy has a calyx of only two sepals, which completely inclose the bud before it expands ; and within this is a corolla of four petals. Some of the tribe, however, possess three sepals and six petals ; but the former is the ordi- nary number. If the stem or leaf of a Poppy be broken, a milky juice runs out ; and its whiteness is due to the narcotic substance, opium, which is diffused through it ; and also, perhaps, to a larger proportion of Caoutchouc than most Vegetable juices con- tain. The Crowfoot tribe have a clear juice ; and this difference, connected as it is with a great difference in the properties of the respective groups of plants, is a very characteristic one. But independently of this, the well-marked difference in the con- struction of the ovary, takes away all difficulty in distinguishing these two orders from each other. 524. The calyx very early falls off, a character by which this order may be distinguished from others of less importance. As the ovary ripens, the exterior becomes very hard and brittle, forming a hollow box termed a capsule, with a brownish-yellow shell. The seeds, when mature, separate from their attachments, and may be shaken loosely in their case. In this condition, the capsules are well known as Poppy-heads, being kept in druggists" shops, on account of the mild narcotic properties, which give the water in which they have been boiled some soothing effects when applied as a fomentation. So hard and firm is the shell of the capsule, that the seeds could not find their way out, unless per- mitted to do so by a particular contrivance. Just beneath the lid, which is firmly bound down to the lower part by the hardened stigmas, there is a set of little valves, which open in the intervals of these (as shown at 2, Fig. 137) ' and through these, the seeds fall out. The structure of the Poppy-capsule is easily understood, by imagining that the several carpels have adhered together, their walls being flattened against each other, just as in the Orange; but that the central portion formed by the union of these has not been developed, so that the partitions are incom- plete, though still projecting more from the sides, than they do in the Heartsease (. 434, Fig. 84). In each case, as the seeds PAPAVERACE^E, OR POPPY TRIBE. 365 are attached to a placenta, which springs from the wall, and not from the centre of the seed-vessel, the placenta is said to be parietal. In the true Poppies, the number of placentae, marking the number of united carpels, is considerable ; but in a British genus (Glaucium) commonly known as the Horned Poppy, the ovary is formed of only two carpels grown together ; and these, when ripe, look like long slender but stiff horns, whence the common name is derived. The scientific name is founded on the sea-green hue of the stems and leaves, which look as if the sur- face had been encrusted with the salt spray. Allied to the Horned Poppy (which grows chiefly on the sea- shore) is a plant termed Celandine (Chelidonium)^ having pale green leaves and rather small yellow flowers which grow in umbels (as in the tribe of Umbelliferce, hereafter to be described), and frequenting waste places, especially near towns and villages. This still more departs from the ordinary type of the Poppy tribe, in the structure of its seed-vessel ; which consists of a single pod separating when ripe into two valves, as in the Pea tribe. 525. A very curious anomaly is met with in a foreign genus belonging to this order, the Eschscholtzia. The flower of this plant, before it expands, is enclosed in a taper-pointed green sheath, which is pushed off by degrees as the petals unfold, and at last drops to the ground. This extinguisher- like organ would seem to be something entirely new. If carefully examined, how- ever, it is found to be nothing else than the calyx, of which the two sepals have adhered so firmly, that they will not separate, in the ordinary manner, to admit of the expansion of the flower; and as it must be got rid of in some way, nature has provided the means of throwing it off, by making its attachment weak at the base, from which it is disengaged. This adhesion of two parts growing in contact with each other, is a very common occurrence in Plants ; and several instances of it will hereafter occur. 526. The plants of this order exhibit, in a greater or less degree, the same tendency to variation, which has been noticed in the Ranunculaceae. This is especially the case with the White Poppy, which is cultivated in gardens on account of the showy 366 PAPAVEBACE^E, OR POPPY TRIBE. appearance of its flowers, when several additional whorls of petals have been developed at the expense of the stamens. Its colour, also, has a tendency to change, but generally to light shades of purple. The deep scarlet Poppies, so abundant in corn-fields, are not so prone to variation. 527. All the Papaveraceae possess narcotic properties in more or less intensity ; but these properties are not common to the whole plant, being only manifested by those parts which abound in the milky juice. Thus from the petals of the Red Poppy a syrup is made, which is used to colour medicines, on account of its beautiful deep-red hue; but this is perfectly destitute of medicinal properties. The seeds, again, yield a large quantity of a fixed oil, which is quite free from any narcotic quality (. 371). From the ripening capsules, however, especially of the White Poppy, the milky juice may be obtained in large quantities; and it is from this source that all the opium, obtained for medicinal and other purposes, is derived. The properties of this drug, and the enormous amount of it consumed, have been already remarked upon (. 384 5) ; and the account need not here be repeated. It may be desirable to mention, however, that a syrup is made from the White as well as from the Red Poppy ; and that the former possesses narcotic properties, from which the latter is wholly free. It should be used, therefore, by unprofessional persons with great caution. There is too much reason to believe, that the lives of many infants have been destroyed, by the administration of tea-spoonful after tea-spoonful of "White-Poppy Syrup, given by ignorant nurses or mothers, with the idea of temporarily soothing them. And it is also well known, that the injudicious use of many excellent popular medicines, into the composition of which opium enters in unknown quantity (such as Godfrey's Cordial, and Daffy's Elixir), has been productive of equally fatal effects. It cannot be too strongly impressed on those who have the management of infants, that they are susceptible of the influence of narcotics in a far higher degree, than of that of purgative and other medicines ; so that whilst an infant may safely take a grain of calomel, or three or four of jalap, one-fifth of the ordinary doses for adults, a single drop CRUCIFER.E, OR TURNIP TRIBE. 367 of laudanum is as much as it is usually safe to give, the dose for an adult being twenty times as much. 528. All the Papaveraceae belong to the Linnsean Class POLYANDRIA, and to the order Monogynia; the style being apparently single, though formed by the union of many. Order CRUCIFER^E, or Turnip Tribe. 529. This order is one of the most important to Man, in respect to the amount of wholesome food which he directly or indirectly derives from it, of the entire group of Exogens. It comprehends the Turnip, Cabbage, Sea Kale, Mustard, Cress, Radish, and other edible Vegetables ; as well as the Rape, culti- vated for the oil yielded by its seed; and Stocks and "Wall- flowers, valued as showy garden-plants. As the flowers are generally small, there might be some difficulty in recognising them ; were it not that they are marked by very obvious cha- racters, which are easily observed, and can scarcely be mistaken. One of these characters is derived from the number and arrange- ment of the stamens ; which throughout the whole of this order are scarcely subject to variation, and which are not presented by any plants that do not belong to it. The number of stamens is six ; but four of these are longer than the rest ; so that they would be characterised in Linnaean classification as tetradynamous (. 483) ; and in fact the Linnsean class TETRADYNAMIA, and this order Crudfera, correspond precisely. The arrange- ment of these stamens, somewhat in the form of a 6 Maltese cross, is another peculiarity, from which the name of the order is derived ; the four long stamens are placed above and below, and the two shorter ones at the sides. Some other less constant characters will be noticed as we proceed. 530. A good example of this Order will be found in a com- mon weed, named Shepherd^ Purse (Capsella Bursa pastoris), which may be found almost everywhere, and at all but the coldest seasons of the year. Its name seems to have been derived 368 CJRTICIFER^E, OR TURNIP TRIBE. from its possessing a number of pouches, filled with very small seeds, which might be imagined to be fairy coins. The flowers, in this plant, are arranged upon the stem in the form which is termed a raceme; by which it is meant, that they spring from it by short stalks nearly of equal length, which arise at intervals ; a bunch of Currants is a very good illus- tration of this form. It will be observed that they are destitute of bracts ; the entire absence of which is a peculiarity of this order ; although many genera of other orders are also distinguished by it. The calyx is formed of four little sepals ; and within these are four very , small white petals : the regular FIG. 139. SHEPHERD'S PURSE; A, whole " . . flower enlarged ; B, stamens and pistil ; c, arrangement of which increases the cross-like aspect of the flower. The stamens alternate with the petals, and are opposite the sepals. The pistil is an oval green body, shaped something like a wedge ; on the summit of which is a cushion-like stigma, mounted on an extremely short style. If the ovary be cut open, it will be found to contain two cells, each of which includes a number of ovules hanging by slender thread-like stalks. It will be observed, however, that the ovules do not originate from one central placenta, but from one attached to each side-wall of the ovary ; and this explains to us (as will presently appear) the reason why the ovary is very often one-celled in this order, and also the peculiar mode of dehiscence of the seed-vessel. The fruit becomes a flat wedge-shaped body, composed of three pieces, two of which, the valves^ separate from the third, which is named the dissepiment ; and it is to the edges of this third piece that the seeds are united. Now each valve is a carpellary leaf, the two CRUCIFER^E, OR TURNIP TRIBE. 369 edges of which are not entirely folded in; and the ovules arise, therefore, from a placenta formed by the thickened edges of each leaf, so that there are really four separate placentae, as is indicated by the four different directions in which the ovules lie (Fig. 140, C). But the contiguous placentae of the two carpels unite together, and project towards the middle of the ovarium ; and in this instance the opposite ones meet each other, so as to form a complete partition. In many Cruciferous plants, on the other hand, they do not meet ; so that the ovary is one-celled, and as the ovules are attached to its sides, the placentae are said to be parietal. The li * w< A fl V """ ., . ., . .. the valves ; 6, the torm of the fruit ditters in the different FIG. 140. A, ripe fruit marks of the places to which explained in the Liimaean Classification the seeds are attached; C, Actn\ j.* ,1 dissepiment with seeds at- ( . 48d), sometimes, as in the present tached; D, section of seed. instance) a snorfc pO( J :; and some- times a long pod or siliqua, as in the Turnip and Cabbage, Stock, and Wall-flower. This distinction is not employed, however, to subdivide the order in the Natural system ; since it is not found to bring together the plants that have really the nearest alliance : and Botanists found their classification of the genera (which, on account of their great number, need to be associated in groups) upon certain minute distinctions presented by the embryo. Throughout the order, however, the structure of the seed is different from that which has been elsewhere seen; for it is entirely destitute of albumen ; and the embryo is doubled upon itself. (Fig. 140, D). 531. All the plants of this order are herbaceous, and most of them are annual. The flowers are usually yellow or white, less commonly purple. It is remarkable that, whilst the characters of the order are so constant, those of the individual are liable to such great variation. This is evident in the species which are cultivated for the beauty of their blossoms, such as the Stock 370 CRUCIFERJ3, OR TURNIP TRIBE. and "Wall-flower ; as long as the flowers remain single, however, they are not valued by the florist ; but it is their tendency to become double, by the development of petals in the place of stamens and pistils, that gives them their richness of appearance. If all the organs of fructification, however, were to undergo this conversion, there would be no means of propagating any particular variety or race which it might be desired to perpetuate. But among the petals, a perfect stamen or two will frequently be found ; and in another flower an untransformed pistil may present itself; if the stigma of the latter be touched with the pollen of the former, the ovules will be fertilised, and seeds will be pro- duced : these, if placed in a rich soil, will have a tendency to develop flowers of a similar character ; but if sown in a barren place, like that which the wild plants inhabit, will probably bear flowers resembling theirs. If, on the other hand, the seeds of a flower departing too widely from the double form, be raised, its flowers will probably be alike imperfect. It is by attention to these rules, that the different races of Turnips, Radishes, &c. have been preserved ; whereas if the seeds of those which do not perfectly exhibit the respective characters of the races, had been used for propagating them, they would all have returned in time to their original common form. 532. It is this tendency to variation under the influence of cultivation, producing the effect valued by the florist in the Stock and Wall-flower, which renders other plants of this order valuable to Man as articles of food. There is a remarkable ten- dency in many of them, to increase the amount of the fleshy portion of their tissues, when abundantly supplied with nourish- ment. This increase takes place in different parts, in different species. Thus in the Turnip and Radish it is chiefly in the root, the natural form of which is often completely changed by cultiva- tion ; yet the seeds of any variety of either of these species, if raised in a poor soil, will produce the tough stringy roots charac- teristic of the original wild plants. In the Cabbage and Sea- Kale, it is chiefly in the stems, leaf-stalks, and leaves ; as is also the case in a less degree with the Turnip. The varieties of the Cabbage are very numerous ; the Scotch-Kale, the Savoy, the CRUCIFER.E, OR TURNIP TRIBE. 37* Cauliflower, and Brocoli, are well-known forms, departing more or less from the orginal stock, the Brassica oleracea or Sea- colewort, which may be found growing wild on the cliffs, near the shores of the greatest part of South Britain, bearing a few small scattered leaves and meagre blossoms. In the Cauliflower, the part most prized as food consists of the flower-stalks, which are enlarged and become succulent under cultivation ; when cut for the table, the flowers have not expanded. Some varietie? of the Cabbage attain a great size. The Palm-kale, which is exten- sively cultivated in the Channel islands, grows to the height of 10 or 12 feet, the stem being very much elongated and bearing leaves only at its summit, so as to give the plant very much the aspect of a Palm ; the inner bud is tender and palatable, and the outer leaves are given as fodder to Cattle. The Tree-kale or Caesarean Cow-cabbage, is said to grow to the height of 16 feet, in some parts of France, where it is cultivated for the same purpose. 533. The Sea-Kale is obtained from another marine species, the Crambe maritima ; the young shoots of which have, time out of mind, been collected by peasants, and eaten as a pot- herb ; but which has only within a recent period become a cheap and common vegetable. In order to prevent it from becoming rank, by the too-abundant formation of its peculiar bitter secre- tion, and stringy, by the production of too many woody bundles, it is necessary to grow it almost in darkness (. 362) ; and this is commonly effected by heaping up earth around the young shoots. A species of Brassica nearly allied to the Turnip, is that which furnishes the Rape-seed, from which a large quantity of oil is obtained by pressure ; whilst the remaining fleshy sub- stance, known under the name of oil-cake, is a very nutritious food for cattle. In all the seeds of Cruciferae, there is a ten- densy to the deposition of a fixed oil in the cells (. 371) ; and this deposite is greatly increased by cultivation in the seeds of this and other species. 534. Among other well-known British species of this order may be mentioned the numerous kinds of Mustard, Cress, Scurvy-grass, Horse-radish, Pepper-wort, and Lady's Smock, 372 CRUCIFERJ2, OS TURNIP TRIBE. or Bitter Cress. Of this last kind, the common meadow species (Cardamine pratensis) has a considerable tendency to become double ; and when its power of reproduction is thus impaired, it has a very curious mode of compensation. The leaflets, whilst still in connection with the parent plant, will strike root into the ground, wherever they come into contact with it ; and from each a new plant may arise. The Isatls sativa, from which the blue dye wood is obtained (. 390), is another native species of this order. 535. The plants of this order are more abundant in Europe than in any other quarter of the globe ; and a very large pro- portion of them are natives of the temperate zones. Their gene- ral character is to possess in some degree acrid and stimulating qualities, such as we meet with in the Mustard, Cress, Radish, Horse-Radish, Pepperwort, &c. When this acrid secretion is dispersed, however, through a large amount of fleshy tissue, as in the Turnip, Cabbage, &c., it does not prevent the plants from being palatable as well as wholesome food. None of this order can be said to be poisonous ; and most of the species it contains are very useful remedies for a most distressing malady, the Scurvy, which was formerly not unfrequent in this country, when all but the highest classes fed upon salt meat during the greatest part of the year ; and which has been, until the late improve- ments in the provisioning of ships, a most dreadful scourge to the crews of vessels undertaking long voyages. The name Scurvy-grass, by which the genus Cochlearia is commonly known, shows the estimation in which it was formerly held in this country, as a remedy for this disease ; and other species are still more efficacious. There could scarcely, perhaps, be men- tioned a more striking illustration of the practical utility of which the Natural System may be rendered, than a fact which occurred at the beginning of the last century. During Lord Anson's voyage round the world, a very large proportion of his crew either lost their lives, or were rendered unfit for service, by the Scurvy ; and although new and unknown lands, teeming with luxurious vegetation, were constantly being discovered, the dread which the surgeon entertained of the men being poisoned TURNIP TRIBE. ROCK-ROSE TRIBE. 373 was so great, that lie would often allow them to use no other kind of fresh vegetable food than grass. If he had been acquainted with the simple fact, that none of the Cruciferse are deleterious, and that all possess (in a greater or less degree) those properties which render them more valuable than any ordinary medicines in the treatment of this disease, he might have been able to restore many to health, by simply explaining to them the very evident marks by which this order is characterised, and encouraging them to seek for plants which exhibit such, and to make use of them without apprehension. 536. The Order CISTACE^, or Rock-Rose tribe, must next be mentioned. Although not a numerous or very important group, it presents several points of interest. The plants it contains flourish in dry rocky places, where others would not find a due supply of fluid nutriment ; and these they ornament with a pro- fusion of blossoms, having brilliant colours. They usually expand in the night, and after a few hours' exposure to the sun, they perish. A few species (belonging to the genus Helianthemum} are natives of this country ; and others, introduced from the South of Europe, are cultivated as evergreen bushes in shrub- beries, or are employed to ornament rough banks and masses of rock-work, over which they trail with great beauty. In the general characters of their flowers, they may be regarded as intermediate between the Papaveracese, and the Violacese the order to be next described. The sepals of the calyx are five ; but these do not exactly form a single regular whorl, as two arise somewhat lower than the others, and are somewhat exter- nal to them. The corolla usually consists of five petals, which, from the manner in which they are packed within the bud, have a crumpled appearance when the flower unfolds ; they fall off at an early period of flowering, whilst the calyx remains as a pro- tection to the seed-vessel. The stamens are hypogynous, and indefinite in number ; and they are usually much shorter than the petals. The ovary is superior, and is either one- celled with parietal placentae, or is divided into five or ten cells by partitions radiating towards a centre. There is never more than one style, and this terminates in a simple expanded stigma. The fruit is a 374 CISTACE^E, OR ROCK-ROSE TRIBE. capsule, usually separating into five or ten valves ; along the middle of each of which there is a placenta, or a partial dissepi- ment. The seeds contain a small quantity of albumen ; and the embryo is very curiously coiled up. All the species, in common with those native to Britain, belong to the Linnaean class POLY- ANDRIA, order Monogynia. 537. This tribe evidently resembles the Poppies, in the tran- sitory character of the flower, as also in the crumpling of the petals ; but particularly in having a large number of hypogynous stamens, and a seed-vessel partially divided, with numerous seeds arising from parietal placentae. But, on the other hand, they are separated by many points of difference ; for the calyx of the Papaveraceae is formed of only two pieces which soon fall off, whilst that of the Cistaceae is composed of five sepals, and is persistent ; the former possesses a milky juice, which the latter do not afford ; in the former, there is a large separate albumen, whilst in the latter there is a small one. Further, they are separated by a peculiar character which is of no small physiolo- gical importance. The foramen of the seed, the aperture by which the fertilising influence is received, and the radicle after- wards makes its way out (. 436), is usually situated at the 'md nearest the placenta ; and the pollen-tubes pass into it, by insinuating themselves along the cord which connects the ovule to it. In the Cistaceae, however, the foramen is situated at the point of the seed ; and the manner in which the pollen-tubes find their way into it is very curious. When they have reached the top of the ovarium, instead of passing down its sides to the pla- centae, they separate themselves into bundles, of which one di- rectly enters each cell of the seed-vessel, and spreads through it like a fine cobweb, lengthening until it reaches the apertures of the ovules. The plants of this tribe chiefly abound in the South of Europe and the North of Africa, being scarcely known in Asia and America. They are not known to possess any pecu- liar properties ; a gum-resin termed Labdanum, which was once used in medicine, is obtained from one species. They are all low shrubs or herbaceous plants. 538. The next tribe which will be noticed is also a small one, VIOLACE^E, OR VIOLET TRIBE. 375 mostly composed of still humbler plants, but containing some well-known species of general interest. This is the order VIOLACE^E, or Violet tribe, the largest of the British species of which is the common Pansy or Heartsease ; this will be convenient, there- fore, to describe in illustration. On looking at the leaves, they will be found to be rather small, and to arise by long stalks, at the base of which are a pair of large stipules ; these are very characteristic of the order. The flower consists of five narrow sepals, some much larger than the rest ; which are usually pro- longed in a curious manner at the base. The corolla consists of five petals, of which, in the Pansy and most other species, two stand nearly erect, so as to appear above the others. These two in the Pansy are differently-coloured ; and a third, standing in front of them, has a short horn or spur at its base. The stamens are also five in number, and generally of irregular form, possess- ing no proper filament, but having a membranous expansion in place of it, which is elongated above the anthers ; two of thew, in the Pansy, have long projections, which are hidden in the horn of the petal. The anthers are often coherent to each other, and lie close upon the ovary. The ovarium is superior, and contains but one cell ; it possesses, however, three parietal placentae (Fig. 84, . 434), to which many ovules are usually attached. There is but a single style ; and the stigma is covered with a kind of hood, so that access can only be gained to it by an aperture on one side. For this singular conformation, no use has been assigned. When the fruit is ripe, it is still sur- O * * rounded by the calyx ; it is an oblong shining case, which splits into three valves, having the seeds adherent to the middle of each. The Heartsease of the gardens has been greatly im- proved in its beauty as a flower by cultivation ; and a number of varieties, differing chiefly in their colours, are known to florists. The common Sweet Violet has no rival among flowers, if we seek for delicate fragrance ; and this is not improved by culti- vation. 539. This order is readily known from all other hypogynous Exogens, by its persistent calyx, its irregular flowers, and by the three narrow parietal placentae situated in the middle of the 376 ORDER DROSERACE.E, OR SUN-DEW TRIBE. same number of valves. In the persistence of the calyx, the prevalence of the number 5 in the flowers, and in the slight division of the ovary, it is evidently allied to the Cistacese. Of the plants contained in it, few are natives of Asia ; and those which inhabit South America differ from the rest, in being shrubby instead of herbaceous. The roots of all the Yiolaceas appear to be more or less emetic ; and those of South America are particularly so, and are used in medicine under the same circunstances as those in which Ipecacuanha is employed in this country. 540. Nearly allied to the violets is the little order DROSERACE^E, or Sun-dew tribe ; so named from the peculiar appearance (presently to be described) of the British species, by which it may be illustrated. The little Sun-dew is a plant whose home is in fens and morasses, where it takes possession of the small hillocks elevated above the surrounding waters ; and it cannot be made to flourish, if transplanted into any other situation. The leaves of this little plant are the most conspicuous part of it, whilst the fructification is the least so. When spread out, they form small concave disks, covered with long shining red hairs, that secrete from their point a clear fluid, which gives the leaves the appearance of being covered with dew-drops. This secretion is most abundant when the sun is at its highest, whilst real dew is only seen on leaves in the early morning ; and it is from this circumstance, as well as from the peculiar sparkling appearance of the surface, that the name of the plant is derived. The hairs, when examined with a high magnifying power, are extremely beautiful microscopic objects ; they are seen to con- sist of an immense number of minute cells, arranged with great regularity ; and if illuminated by a strong reflected light, the rays from below being cut off, they exhibit a most gorgeous variety of brilliant colours. The fluid secreted from their points has a slightly acrid taste, and it appears to retain insects which settle upon it. The hairs themselves exhibit a considerable degree of irritability ; slowly curving inwards, and entrapping any unfortunate victim that may have come within their reach. This irritability is manifested to a much greater degree in the: SUN-DEW TRIBE. ORDER CARYOPHYLLEJE. 377 Dioncea. (. 246) which is an American species of this order ; and it is common, in a greater or less degree, to the other known species of it. The organs of fructification are nearly allied to those of the Violacese. The flower is regular, however ; the stamens have the usual form, and are sometimes double or triple the number of the petals ; and the ovary bears from three to five styles. The order is also peculiar as to the manner in which its leaves and flowers are folded together before their expansion. Instead of being simply compressed into buds, they are coiled in a spiral ; so that, when unfolding, the leaf-stalks and flower- stalks somewhat resemble a shepherd's crook. This form of development is the same as may be readily observed in the unfolding leaves of the young Fern. (See the highest leaves in Fig. 3, . 23). 541. Passing over several Orders which contain but few species, and these of little general interest, we stop for a short time at one which contains many well-known British plants, the CARYOPHYLLE^E, or ChicJcweed tribe. These are natives principally of the temperate and frigid parts of the world, where they inhabit mountains, hedges, and waste places. Those which are found within the tropics are usually natives of elevated or mountainous tracts, almost always reaching the limits of eternal snow, where many of them exclusively vegetate. The greater part of them are regarded as mere weeds ; but some of them are greatly improved by cultivation, and become handsome garden plants, whioh are greatly valued. Such are the Clove-Pinks, Carnations, and Picotees, which are all varieties of one species, the Dianthus Caryophyllus, that naturally grows about old walls, especially on the ruins of ancient castles. The structure of the flower may be best understood from some of the larger species, such as the common Pink ; taking care, however, not to choose a double one. It is interesting to remark that whilst in this plant, the leaves being long and narrow, with only a single vein running from one end to the other do not afford any cha- racters by which it might be known as an Exogen, the petals (which are but differently- developed leaves) have a beautiful system of veins, which are evidently reticulated. The stems are 378 ORDER CARYOPHYLLE^E, OR CHICK WEED TRIBE. very much swollen at the points from which the leaves arise : A B and this is a character which marks the whole order. The calyx is a tube composed of five sepals united to- gether, and separated only at their points. Fig. 141. DIAGRAM OF THE FLOWER or CARYOPHYLLB^E. Five petals arise from A. vertical section. B, horizontal section. the lower ends are very narrow, whilst the upper ends are greatly expanded, and are irregularly jagged at their borders. The stamens are ten in number, with short stalks. The ovary is one-celled ; and in its centre is a column, round which a great many ovules are clustered. In the Pink there are two styles, each terminating gradually in a narrow' fringed stigma ; in other species there are three, and in others five styles. The first becomes a dry capsule, opening from the point by four valves. The structure of the seed is variable. 542. This order may be distinguished from all other polype- talous Exogens, by the possession of opposite undivided leaves without stipules, and by the tumefaction of the stem at the nodes; it is further separated from others having the same number of stamens, by the structure of the ovarium. This is one of the orders in which a certain amount of variation occurs in the number of the parts of the flower ; which are sometimes arranged on the quaternary type, or in fours, sometimes on the quinary, or in Jives. The stamens are almost invariably twice as numerous as the petals. Hence, while most species of this order are comprehended in the Linnsean class DECANDRIA, a few fall into Octandria ; they of course belong to the orders Digynia, Trigynia, and Pentagynla^ according to the number of their styles. The order is divided, in the natural arrangement, ac- cording to the adhesion or separation of the sepals of the calyx. The division in which the calyx is tubular contains, with the Pink, the Silene or Catchfly, named from often secreting a viscid matter in which flies are caught ; the Cockle (Agrostemma) y CHICKWEED TRIBE. ORDER LINAGES. 379 which is often a very troublesome weed in corn-fields ; the Ragged Robin (Lychnis jlos-cmuli), frequent in meadows; and the Bachelors' Buttons ( //. dioica\ which is an exception to the general rule, in being dioecious. The second division, which has the sepals distinct, contains the numerous species of common Chickweed or Stitchwort (Stellaria), the Mouse-ear Chickweed (Cerastium*), of which some species are peculiar to Alpine dis- tricts, whilst another affects moist situations ; and the Sandwort (Arenaria), so named from the character of the soil in which most of its species flourish best, though some of them are only found in rocky and mountainous places. In regard to the pro- perties of this order there is little to be said. The species belonging to it are in general both insipid and inodorous. Many of the wild species seem to be sought as favourite articles of food by small animals, and some have been cultivated as fodder for cows, the quantity of whose milk they are said to increase. 543. The succeeding order is one which contains but a small number of genera; but these are distributed over the whole world, and afford a product of the greatest importance to Man. This is the order LINAGES, or Flax tribe, which was once asso- ciated with the last order, but differs from it in so many impor- tant characters, that it is separated with complete propriety. In the first place, the stems of the Flax are not swollen at the nodes, and the leaves are usually not opposite. The sepals of the calyx, which are always distinct, are not arranged in a con- tinuous whorl ; but two are external, partly overlapping the others, which are in- CM f (D / 'flX ternal; tW^an^g 6 - ment, which is termed imbricated, is quite dif- ferent from that which we have seen in the Chickweed tribe. The FIG. 142. DIAGRAM OF THE PARTS op THE FLOWER IN two Outer Sepals are THK ORDER LlNACEJE. 1 J * V. JJo marked * in the dia- gram. The whole number is generally five, sometimes four. The petals are always equal in number to the sepals. The c c2 380 ORDER LINAGES, OR FLAX TRIBE. stamens are equal in number to the petals, and are united at the base into a downy cup ; the edge of this exhibits, between the stamens, a corresponding number of little teeth, which are the abortive rudiments of another whorl (. 465). Within these is the ovary, which appears to contain ten cells, in each of which is a single pendulous ovule ; but the number of real cells is only five (in some species four), of which each is partly divided into two by an imperfect partition, extending inwards from its outer wall. Such a partition is termed a spurious dissepiment. The ovary bears five (or four) styles and stigmas ; and finally the seed-vessel splits into ten valves. By all these strongly-marked differences, the real affinity of the Linaceae to the Caryophyllese is rendered very small. 544. There is scarcely any plant which is less affected than the common Flax, by differences of soil and climate ; and accord- ingly one species, with all its characteristics unaltered, flourishes in the cold as well as the temperate regions of Europe, in North and South America, in Africa, and in Asia. There are few plants which are made subservient to so great a variety of uses ; from which circumstance it is, that this species of Linum has received its specific name usitatissimum, which means " in most common use." It is from the woody fibre of its stem, that all the thread is obtained, which has been from very early ages employed in making linen fabrics (the name of which is derived from that of the genus) ; and it is now used for this purpose to a greater extent than ever, in spite of the degree in which it has been superseded by cotton. The seeds contain a large quantity of oil, which is readily obtained from them by pressure, and is known under the name of linseed oil (. 371) ; and the oil-cake which is left is an excellent food for cattle. The seed-coats also contain a large quantity of mucilage ; so that an infusion of the seeds, known as linseed-tea, is frequently of great utility as an external soothing application, and is sometimes a very useful internal remedy. Further, the seeds, when ground into a meal, form the most advantageous material for large poultices ; and an enormous quantity is consumed for this purpose, especially in hospitals. The plant, however, is not much cultivated in Britain, ORDER LINACEJE. FLAX PLANT. 381 notwithstanding various inducements held out by the legislature ; for its crops are of inferior value to corn ; and it is found to render the soil more unfit for the subsequent growth of other crops, than does almost any other cultivated vegetable. The principal supplies required for British manufacture are drawn from Russia, the Netherlands, and Prussia ; some is also brought from France and Egypt, and even from New South Wales. The annual imports vary from 40,000 to 7^,000 tons of flax ; and about two million bushels of linseed. Flax is grown, how- ever, in Lincolnshire, Somersetshire, and Yorkshire, to a small extent ; it is more cultivated in Scotland ; and nearly all that is required for the extensive linen factories of Ireland is the produce of that country. 545. The common Flax-plant is an annual, which shoots forth slender upright hollow stalks, about the thickness of a crow-quill. These are surrounded by a fibrous bark or rind, containing woody bundles intermixed with cellular tissue. When the plant has attained the length of about 2J or 3 feet, it divides into slender flower-stalks ; but there is a considerable difference in the dimensions of the stem, according to the soil, season, &c. This difference governs the treatment of the plant ; for, if the stem be short and disposed to branch, the plant is considered more valuable for its seed than for its fibrous bark, and is not gathered until its seeds are fully matured ; whilst if the stem grows long and straight, all care of the seed becomes a secondary consideration, and the flax is pulled at the most favourable period for obtaining good fibres, which is a little after the wither- ing of the blossom, before the seeds are quite ripe. The Dutch are accustomed to lay up the plants in stacks, as soon as they have pulled them ; experience having shown that, in most instances, seed will ripen after the parent-plant has been pulled, provided that it be not detached from it, being supplied by the sap which it contains ; and thus both good flax and seeds may be obtained from the same crop. The stems are freed from the leaves and seed-vesels by a process called rippling; which means passing them through a sort of comb with long teeth, by which these parts are torn off. The flax is then placed in water, to 382 PREPARATION OF FLAX. dissolve the gummy sap, by which the bark adheres to the woody portion of the stalk, and to favour the decomposition of the soft cellular tissue by which the woody bundles are held together. This process, which is called water-retting, renders the water offensive, and is said to be unhealthy to the neighbourhood ; and an act preventing its being carried on in any common stream or pond, is in force in this country. The length of time required varies from about 10 to 15 days, according to the state of the flax, the temperature of the water, &c. It has been recom- mended as a much better method, to steep the flax in hot water for a short time, with soft soap. The water-retting of fine flax, for the manufacture of the most delicate cambrics and muslins, is attended to with great care ; it is particularly necessary that there should be a constant renewal of the water, as the fibres will otherwise acquire a dark" tinge, of which it will be almost impossible to get rid by bleaching. The fibrous bundles are then separated from the rest of the tissue, by being passed between two surfaces, one of which has grooves, into which enter projecting ridges on the other. In former times, and in some countries at the present, a very simple machine is used for this purpose, termed a break; this consists of two long blocks, cut in the manner just described, united by a hinge at one end ; the lower one being supported, the upper is lifted at the other end by the right hand, and the stems are drawn with the left between the two jaws of the break, which are made to close together forcibly several times, so as to bruise the stems and separate their parts from each other, without breaking the fibres. After this another operation is required, to separate the smaller particles of bruised refuse from the flax ; this is termed scutching. These two operations are now usually performed together by a machine, principally consisting of three cylinders with ridges and indentations that work into each other ; and between these the flax is passed. After this, the flax is heckled, by drawing the bundles through a frame studded with rows of sharp pins ; this effectually frees it from all extraneous matter, and presents a series of smooth distinct filaments. It is then ready for the spinner. The finer kinds of flax, however, are prepared in a more FLAX. ORDER MALVACEAE. 383 delicate manner ; being merely scraped or cleansed with a blunt knife on a soft skin of leather, and afterwards dressed with a kind of brush. Machine- spinning has now almost superseded hand- spinning in this country ; but the finest thread can be produced only by the latter process. By machinery a thread measuring 12,000 yards has been spun from one pound of flax ; but by hand- spinning a thread of three times that length has been produced from the same weight. 546. The only other species of this order, which is cultivated for the same purpose, is the Siberian perennial flax. This is a much taller plant, having coarser fibres ; these are found to be very strong, but not so white or fine as those obtained from the common flax. They serve very well, however, for the manufacture of coarse fabrics ; and there is this advantage attending the cul- tivation of them, that from the same root, a succession of stalks will be developed for many years ; so that they require no further attention, than to be kept free from weeds. The juices of all the plants of this order seem to have a purgative quality; this is very slight in the common Flax, but is greater in the common Linum catharticum or Purging-flax of this country, as well as in some foreign species. Order MALVACEAE, or Mallow Tribe. 547. Almost every child is familiar with the cheeses that he finds among the hedges; and there is not a civilised human being who does not make great use of cotton fabrics ; yet few, save professed Botanists, are aware how close a relation there is, between the humble neglected plant that bears the former, and the cherished exotic shrub to which we are indebted for the latter. They both belong to the same order, which is marked by characters that readily distinguish it, and which may be ex- plained from the common British Mallows, as well as from any other of the more highly-prized species. Of the former there are two kinds, one bearing small pink blossoms, the other large purple ones, which are among our handsomest wild flowers. The latter, which may be best chosen for examination, grows 384 ORDER MALVACEAE, OR MALLOW TRIBE. two or even three feet high, in places where it is not cropped by cattle ; its stem is covered with longish hairs, which frequently spring in stellate (star-shaped) clusters ; its leaves are roundish, slightly divided at their edges, and possess small scale-like stipules at the base of their petioles. The sepals are five, and are placed in a uniform whorl ; they are partly adherent ; and on the exterior they have three bracts, so arranged as almost to resemble an additional calyx. The petals are also five ; pre- viously to their ex- pansion they are folded together in a very cu- riously-contorted man- ner. The stamens are numerous ; and their filaments adhere at FIG, 143. DIAGRAM OF THE FLOWER OF MALVACEAE, their lower part, SO as to form a tube which embraces the pistil. This structure is exactly what is termed, in the language of the Linnaean classification, monadelphous ; and the whole of this order, therefore, belongs to the Linnaean class MONADELPHIA*. The anthers only possess one lobe, which opens transversely. The pistil is composed of several united carpels, each of which has its own style arising from its summit ; the styles, like the stamens, are united at their lower part into a tube. The seed-vessel is divided by complete partitions into numerous cells, each of which contains one or two ovules ; and when cut across in its unripe condition, the ovarium exhibits a very beautiful aspect, from the regularity of the arrangement of its contents. When ripe the carpels readily separate. All the characters now enumerated, with the exception of the number of sepals and petals, which varies from three to five in each whorl, are common to nearly the whole order. 548. The British species are not numerous ; they consist of four of the genus Malva, or ordinary Mallow, two of the Althaea or Marsh-mallow, and one of the Lavatera or Tree-mallow, so called from its higher growth. These are remarkable for little else than the quantity of thick transparent mucilage, which ORDER MALVACEAE. COTTON PLANT. 385 almost ail the green parts yield ; and on this account they are thought to afford useful remedies in some pectoral complaints. They do not possess, however, any active properties. It is be- tween the tropics, that the most remarkable species of Malvaceae abound ; and this seems to be the natural habitation of the Order, since the proportional nnmber of species belonging to it in any country, diminishes rapidly as we pass from the Equator to the Poles. The showy Hollyhocks, now naturalised in our gardens, are species of Malvaceae introduced from a warmer climate. The genus Hibiscus is remarkable for the striking aspect of its flowers, which are much cultivated in hot-houses in this country ; their stems contain strong and tough fibres, which have been used as a substitute for flax and hemp in making cordage. (It is said that whips, formerly employed by slave-drivers in the West Indies, were made of the plaited fibres of chis plant). The unripe fruit of one species of Hibiscus, known in the East and West Indies under the name of Ochro (in some places Gobbo), is used, on account of the abundance of its mucilage, to thicken soups. Other species of this genus contain a powerful colouring principle, which gives a black stain to anything which it touches ; and the leaves of a species of Althaea are said to yield a blue colour not much inferior to indigo. 549. Of all the genera of this order, however, there is none so important to man as that which yields Cotton ; and it may be questioned if there is any other single tribe, except the Grasses, with which he would now find it more difficult to dispense. Cotton is derived from several species of Gossypium, which are cultivated in both the Old and New World; of no part of Europe, however, are any of these species natives, though cotton has been cultivated in the southern parts of Spain and Italy. There is much uncertainty as to the real number of species ; as the genus is one in which there is a great tendency to the pro- duction of varieties. It is desirable, however, that their re- spective characters should be well ascertained ; since the differ- ences in their produce make the knowledge of them of great importance to the cotton-planter, as this varies greatly both in quantity and quality. Some yield their downy harvest twice 3 SO COTTON PLANT. in the year ; others only once. Some bear cotton of a long and delicate fibre, and of a beautiful whiteness ; whilst the fibres of others are short, coarse, and of a bad colour. These differences are strongly marked in the cotton imported from different coun- tries ; thus the American cotton fetches a much higher price in the market than the Indian ; and, though it cannot be questioned that the soil, climate, and care in gathering, have a considerable influence on the goodness of the article, yet it is also as certain that great improvements might be effected, by replacing inferior species or varieties by others of more value. This is now being attempted in India. 550. The fibres of Cotton are obtained from the seed-vessel, in which they are packed round the seeds; and no further trouble is necessary to obtain them, than to withdraw them when the capsule bursts. This should be done as early as possible : since exposure to the sun gives a yellow tinge to the cotton. These fibres do not consist, like those of flax, of woody tubes ; but they are composed of cellular tissue ; and they are conse- quently much weaker in proportion to their diameter. The greatest difficulty in the gathering of cotton, consists in the separation of its fibres from the seeds they enclose, to which they sometimes adhere with great tenacity ; the firmness of this ad- hesion varies in different species ; and that is to be preferred, therefore, in which the cotton is most readily freed. In the greater part of India, the use of machinery for this purpose is unknown ; and the cotton is cleansed by hand ; in America, however, large machines are employed, which accomplish it very rapidly and effectually. A species of Gossypium cultivated in China is remarkable as having naturally a coloured fibre ; it is from this that the Nankeen cotton stuffs are made, which were at one time commonly worn in this country, and the name of which was derived from that of the place where alone they were manufactured. 551. Notwithstanding the enormous amount of raw Cotton now imported into this country for the supply of its manufac- tories, the employment of it in Britain, to any considerable extent, is comparatively recent. In the 17th century, the COTTON PLANT. ORDER BOMBACE.E. 387 trifling supply required was obtained wholly from Smyrna and Cyprus. In the year 1786, about 20 million pounds were im- ported ; of which about a quarter was from Smyrna, &c., an- other quarter from the British West Indies, and the remainder from other colonies. Shortly after that period, when machines for spinning cotton-yarn were devised by Arkwright and others, the annual consumption of cotton increased six-fold, and it has been progressively augmenting ever since. From all quarters of the world does the raw material now flow in upon us ; and it is converted, with an expedition scarcely credible, into textures, of which a large part are re-conveyed to the countries which ori- ginally furnished it. In the year 1838, the quantity imported was upwards of 500 millions of pounds ; whilst of this there was exported in the form of woven stuffs nearly 700 million yards, and of twist and yarn about 115 million pounds; the value of which, together with that of the cotton hosiery and small wares exported, would amount to about twenty-four millions sterling. When machinery was first introduced, it was made capable of spinning a pound of cotton into yarn 160 miles long ; and a much greater degree of fineness may now be attained. The hand-spinners and weavers in India far outdo machinery in the delicacy of their fabrics, some of their muslins being expressively termed "woven air;" but so great is the saving effected by machinery, in the production of all cotton fabrics but such as these, that a large proportion of those used in India are ex- ported from Britain ; it being a saving of expense to cause the materials thus to undergo the double voyage, although labour is so extremely cheap in India. 552. Nearly allied to the order Malvaceae, which contains few save herbaceous or shrubby plants, is the order BOMBACE^E, or Silk-cotton tribe, none of which are herbaceous, whilst some species are amongst the most remarkable examples of arboreal vegetation, such as the celebrated Baobab trees of Senegal. (. 129). One of the trunks of this species has been found to be of the enormous girth of from 90 to 100 feet ; the spread of the branches and roots is enormous ; one main root, uncovered by a stream, having been traced to 100 feet from the stem, and pro- 388 ORDER BOMBACEJE, OR SILK-COTTON TRIBE. bably extending much further. The height of the trunks, how- ever, does not bear the usual proportion to their thickness, being in general but little more than their diameter. In the interior parts of Africa, at a distance from rivers, the trunks of these trees are converted by the natives into tanks, their heads being cut off, and their immense bodies hollowed out for the reception of water, which m consequence of the softness and lightness of the wood, is not a difficult task. On the eastern coast of Africa, this tree is very liable -to be attacked by fungi, which prey upon its heart-wood, and, without changing its general appearance, destroy the life of the tree, and render the timber very soft. Such trees are hollowed out by the natives as burial-places for the bodies of those who are supposed to hold communion with evil spirits ; and these, being suspended in the chambers thus constructed, become dry, and are well preserved like mummies. The bark of the Baobab yields a coarse thread, of which ropes and cloths are made ; and its fruit contains a mealy pulp around the seeds, which forms a wholesome and agreeable article of food. 553. The species yielding the Silk-Cotton of South America is also a large tree having a light wood ; this is frequently employed for making canoes, and a single trunk has been known thus to hold 150 men, or twenty-five tons of sugar. The tree derives its name (Bomlax, resembling that of the Silkworm), from the peculiarly silky character of the hairs, which surround the seeds, in the same manner as the wool of the Cotton. This wool is commonly used to stuff cushions and beds ; and lint and a sort of felt have been made from it ; but it cannot be spun into threads, in consequence, it is be- lieved, of the absence of the minute roughnesses, which exist upon FIG. 144. BOMBAX. ORDER BROMACE,E, OR CACAO TRIBE. 389 the surface of the true Cotton fibres, and which are very important in binding them together. The difference between the Bombacese and the Malvaceae, in any other respect than their size, is not great. The calyx of the former is not exactly valvate ; the tube formed by the adhesion of the stamens is cleft at its upper part into five divisions ; and the anthers, which, like those of the Malvaceae, are one-celled, burst longitudinally instead of transversely. They resemble Malvaceae also in the mucilaginous character of their juices, and in the entire absence of any deleterious properties. They are all natives of tropical climates. 554. Another order nearly allied to the Malvaceae, is that of BROMACEJE (the Byttneriaceae of De Candolle) or Cacao tribe. They are usually shrubs or trees, which are, like those of the last order, confined to tropical regions and countries bordering on them. They have no very obvious differences from the Mal- vaceae, except that the petals are often absent, and that the anthers are two-celled, bursting longitudinally. The stamens are variously united, but usually form a single tube ; not unfre- quently many of them are abortive ; and, as in the Cacao itself, they assume the form of narrow petals intermediate between the true stamens. The carpels are less numerous than those of the Malvaceae, varying from three to five ; and the number of ovules in each cell is usually much greater. Like the Malvaceae, these plants are remarkable for the quantity of mucilage they con- tain ; and it is from one species that the Gum Tragacanth, so much used in the arts (. 380), is obtained. In a few species, the juices possess a slight acridity ; and in others some astrin- gency. 555. The order is chiefly interesting on account of the im- portance of the genus Theolroma Cacao, in yielding the material of a wholesome and nutritious beverage, the occasional use of which in this country gives but a slight idea of the large quan- tity consumed in many others. It is a little curious that, whilst the generic name, signifying "food for the gods" was given to it by Linnaeus, on account of his high estimation of its qualities, a traveller of the sixteenth century declared that chocolate was a drink " fitter for a pig than for a man." The Cacao tree 390 CACAO PLANT. usually to the height of about 20 feet, though sometimes it attains an elevation of 30 or 40 feet ; its leaves are large, oblong, and pointed ; whilst its flowers are small, and of a pale red. The calyx consists of five sepals of a deep red; and within these is a corolla formed of five petals, the form of which is peculiar. They are broad and channelled into a sort of gutter at their lower part, in the middle they are extremely narrow- 145. FLOWER OF THEOBROMA CACAO. , ,., . 1. Complete flower; a, a, the petals ; 6. 6, the petal-like *d; and they expand stamens ; 2, the tube formed by the adhesion of the stamens, again towards the cut open, showing the five true stamens alternating with ., ... five abortive ; 3, pistil, with a single style composed of five Summit, at WlllCll adherent carpels, and surmounted by five separate stigmas, they adhere. The stamens form a tube, on the upper end of which the five that bear anthers alternate with the other five that have a narrow petalline form ; and the latter, in the complete flower, are seen projecting above the ring formed by the adhesion of the top of the petals. The pistil is formed on the same general plan as in the Malvaceae, consisting of five adherent carpels, each of which has its own style and separate stigma ; but the ovules are nume- rous, varying from 20 to 100 in the whole capsule. 556. The fruit, when ripe, is a long oval, of which the sur- face is covered with rounded eminences, and is marked by ten furrows; its interior cavity is simple, in consequence of the obliteration of the original partitions ; and the seeds are grouped round a central column. They are imbedded in a sort of mealy pulp, which, although sweetish, has a disagreeable flavour. This pulp is sometimes removed from the seeds by washing, after which they are dried in the sun ; and sometimes, in order to get rid of it, they are buried in the soil, until it is detached by decomposition. The seeds are then prepared by roasting, after which their hard husks are easily detached ; and the fleshy interior is beaten up into a smooth paste, which is afterwards ORDER BROMACE^E, OR CACAO TRIBE. 391 dried. Chocolate differs from cacao, simply in the addition of various spices and flavouring ingredients. It is much more employed in France than in England, and is commonly drunk for breakfast in Spain. In Mexico it is considered an article of prime necessity ; and it was extensively cultivated there, at the time of the Spanish invasion of South America. Humboldt, the celebrated traveller, remarks, that it is by chocolate and maize-flour, that man has been enabled to penetrate the vast uninhabited forests of central America, and to gain access to the stupendous table lands of the Andes. The seeds were employed as coins, in order to express values below sixpence, which was FlG - 146 FRUIT OR CAP - . . SULK OF CACAO-PLANT, that of the smallest metal com, six of them containing the seeds or being about equivalent to a halfpenny ; and this use of them is still partially continued. A kind of buttery substance may be extracted from the seeds of the Cacao, which is said to have a very bland and agreeable flavour, and to serve as an excellent emollient application to the skin ; whence it is highly prized, in some countries, as an ingredient in ointments and cosmetics. It was estimated that, in 1806, about 23 mil- lion pounds of Cacao were imported into Europe from South America, Mexico, and the West Indian islands ; of this quan- tity, the greater part was consumed in Spain. The quantity consumed in Britain in the year 1831 was not more than half a million of pounds, but in that year the duty was lowered from sixpence to twopence a pound ; the consumption immediately doubled, and it is now two millions of pounds annually. A large quantity is employed in the British navy and merchant- service, as a partial or entire substitute for ardent spirits ; and it may be expected that the rapidly-increasing disuse of the latter most injurious liquors, will occasion a still further demand for this wholesome and nutritious article. 557. The order TILIACE^E, or Linden tribe, is also nearly allied to Malvaceae. The principal part of this order consists of 392 ORDER TILIACE.E, OR LINDEN TRIBE. herbaceous plants, with handsome flowers, which abound within the tropics ; some species, however, are lofty trees ; and these, contrary to the general rule, are natives of temperate regions. Three species of Linden or Lime-tree are found in Britain ; of which the largest and best known was probably not originally a native of this country. This last sometimes grows to a great size ; and its wood, being light, soft, smooth, close-grained, and not liable to be worm-eaten, is valued by carvers for ornamental works, and also forms one of the best kinds of charcoal for the manufacture of gunpowder. Its flowers are very fragrant, and are a favourite resort of bees, who obtain from them not only honey but a large supply of pollen, which they store up for the nourishment of their young ; and if a hive of bees is at no great distance from a grove of limes, it may be known when these are in flower, by the large number of bees that will return laden with little pellets of the bright yellow pollen which these blos- soms furnish. There are perhaps no trees which form so beau- tiful an avenue, the peculiar mode in which the branches arise from the stem and meet above, giving them very much the aspect of the Gothic columns and arches of a cathedral ; and when the lover of Nature walks beneath their luxuriant foliage, " at dewy eve distilling odours," he feels them to constitute a fit temple for the worship of Nature's God. The characters by which this order is distinguished are such as to show its near alliance with the Malvaceae. The calyx consists of four or five valvular sepals ; and the corolla of an equal number of petals, which are rarely wanting. The stamens are indefinite in number, and net united into a tube ; and the anthers are two-celled, bursting longitudi- nally. The pistil is formed of four to ten united carpels, having a single style, and stigmata equal in number to the carpels, as in the Bromaceae. The partitions are permanent, so as to divide the fruit into cells. They are at once known from the Mal- vaceae and two succeeding orders, by the non-adhesion of the stamens ; and from the Malvaceae and Bombaceae by their two- celled anthers. In their general properties, the Tiliaceae resem- ble the Malvaceae ; they are quite harmless, and contain a con- siderable quantity of mucilage. The sap of the Lime abounds ORDER CAMELLIACE^E, OR TEA TRIBE. 393 in saccharine matter, from which a good sugar has been ex- tracted, and a pleasant wine obtained by fermentation ; and its nuts are said to possess, when roasted, something of the flavour of chocolate. The bark of most species of the order is tough and strong, and easily separable into layers ; and from these, mats, baskets, and cords are made in many countries. 558. The small order DIPTEROCARPEJE, nearly allied to this, is worthy of notice, on account of its containing the Camphor- tree of Sumatra, from which our chief supplies of camphor (. 383) will probably hereafter be obtained, though they are at present derived mostly from a species of Laurel. This product is stored up in the former, in receptacles (. 98) sometimes a foot and a half long ; but the tree must be deeply cut into, in order to open these. Some other trees of this group (which is entirely confined to tropical climates) afford small quantities of resin ; it is from one of these that the Piney tallow (. 382), and from another that Copal (. 377)> is obtained. 559. The next order to be particularly noticed is one of special interest, from its furnishing a product which, without being in the least nutritious, is considered by the Englishman, in almost all ranks, as one of the most indispensable articles of his diet. This order is that of CAMELLIACE^E, the Camellia tribe, well known to the Horticulturist for the beauty of its flowers ; and it is from various species included in it that Tea is obtained. The Camellia, now cultivated in most gardens, will afford a good illustration of the characters of the order, which approach those of the succeeding one. The calyx is composed of from 5 to 7 sepals, unequal in size, of rather tough consistence, and in FLOWER OF some degree overlapping each other. The petals are from 5 to 9, also occasionally imbri- cated, and sometimes slightly The number of stamens is indefinite ; and FIG. 147. STRUCTURE o TEA PLANT. A, calyx, with ovarium cut across. B, petal, with bundle of stamens adherent to it. C, vertical Vction of ova- rium, with the three styles. adherent at the base. 394 CAMELLIA PLANT. TEA TRIBE. they are generally united at the base into one or more bundles. The ovarium is formed of from 3 to 6 carpels, more or less united, with separate styles ; each cell originally contains several ovules. In the ripe capsule, there are only three cells, each con- taining but one seed (the other ovules not having been deve- loped) ; and this is large, with fleshy cotyledons that contain a large quantity of oil, and is destitute of albumen. The Camel- lias are celebrated for the great beauty of their foliage, and the splendid colours of their blossoms, which vary through every shade and mixture of red and white. The C. Japonica is a lofty tree in its native country ; and even in our conservatories it some- times reaches a considerable size. The leaves of some species of Camellia have been used as Tea ; but this is properly derived from the genus Thea. 560. Notwithstanding the many different kinds of Tea ex- ported from China, it has now been ascertained that they are FIG. 148. TEA PLANT. all the produce of two species ; one of them called Thea viridis, from its having been supposed to be the plant employed in making green tea ; the other called Thea bohea, having been in CAMELLIA TRIBE. TEA PLANT. 395 like manner considered the black tea plant. It is now quite certain, however, that both kinds of tea may be produced from either species, the chief difference between these articles being dependent upon the mode in which they are prepared. The black and green teas of the northern district of China, from which the foreign markets are chiefly supplied, are the produce of the Thea viridis ; whilst the teas of both kinds mauufac- tnredin the neighbourhood of Canton, are obtained from the Thea bo/iea. By some botanists these two species are regarded as varieties of the same; each of them is liable to undergo nume- rous variations, under the influence of soil, climate, exposure, &c.; and to these differences, in combination with diversities in the time of gathering the leaves and in the mode of pre- paring them, we are to ascribe the great number of varieties in the product. In the preparation of black tea, the leaves are exposed to air after being picked, but are kept cool until they begin to emit a slight degree of fragrance, apparently in con- sequence of having undergone an incipient fermentation, like that which produces the aroma of hay. They are then roasted at a moderate heat over the fire, until they give out a fragrant smell and become quite soft and flaccid ; after which they are rolled under pressure, again roasted and rolled until the juices are pressed out, and finally dried and twisted between the fin- gers. On the other hand, in order to make green tea, the leaves are roasted as soon as possible after gathering ; and they are exposed in this process to a much higher temperature than that employed for black tea. They are then spread out to cool, and afterwards again roasted at a lower temperature. When cooled a second time, they are of a dark olive colour. In the third roasting, which is the final drying, the heat is again diminished; and it is then that the colour of the leaves changes to that bluish tint, resembling the bloom of fruit, which gives to this tea its peculiar appearance. The peculiar properties of green tea are obviously due to a chemical change, brought about by the action of a high temperature on the juices of the leaves ; and it is only in the inferior kinds that any artificial colouring DD2 396 INTRODUCTION OF TEA INTO ENGLAND. ingredients are employed. The Tea plant is cultivated in China from about the 27th to the 33d degree of north latitude; but it will flourish in regions more distant from the Equator if the climate be mild and equable. It has been found growing wild over extensive tracts in Assam, at the north-east of Hindostan; and attempts are now being made to cultivate it there on a large scale 561. The history of commerce does not furnish any parallel to the circumstances which have attended the introduction of Tea into Great Britain. The leaves are said to have been first em- ployed by the Chinese to cover the taste of their water, which is in many districts brackish and unpalatable; and the infusion being found to be pleasant in its flavour, and productive of an agreeable excitement, the practice of drinking it gradually ex- tended in those places where the water was good, and at length was introduced into Europe. The leaf was first imported by the Dutch East India Company in the early part of the seventeenth century ; but it does not appear to have found its way to Eng- land until about the year ] 650. The first historical notice of it is in an Act of Parliament of the year 1660, in which it was enumerated as one of the beverages sold in coffee -houses, on which a duty was to be laid. That it was not then a common drink, is evident from an entry in the private Journal of Mr. Pepys, Secretary to the Admiralty, who says, Sept. 25, 1661, " I sent for a cup of tea (a China drink), of which I had never drunk before." In 1664, the British East India Company sent two pounds of tea as a present to the King. In 1667 they issued their first order to import tea, directed to their agent at Bantam, to the effect that he should send home lOOlbs. of the best tea he could get. Since then, the consumption has gone on regularly increasing. In 1734, the quantity imported was about 632,0001bs ; in 1768, it was nearly seven million pounds; in 1800, it was twenty millions ; and during the last four years of the East India Company^ charter, the average quantity imported was 31 J millions. Since the abolition of the monopoly, and the conse- quent reduction of prices, the consumption has increased still more rapidly ; the amount imported having in some years nearly reached 50 million pounds, of which above 44 million pounds were consumed in Great Britain and Ireland, a quantity much AURANTIACE^E, OR ORANGE TRIBE. 397 exceeding that consumed in all the rest of Europe and America. To provide a sufficient supply of this article, many thousand tons of the finest mercantile navy in the world are annually employed, in trading with a people by whose government all dealings with foreigners have until recently been discouraged; and an important source of revenue, averaging from three to four millions sterling, is obtained, through a moderate duty upon its importation, by the state. 562. Although the plants of this order which are known in European gardens, are chiefly from China or North America, these form but an inconsiderable part of the whole; 7 or 8 species being all that are contained in the first of these countries, and 4 in the latter ; while between 60 and 70, all beautiful trees and shrubs, are natives of the woods of South America ; and about 20 more are known in the East Indies. Order AURANTIACE^E, or Orange tribe. 563. The group of plants producing Oranges, Lemons, Limes, Citrons, Shaddocks, Forbidden-fruit, and the like, is readily distinguished from the rest of the Vegetable Kingdom, by several evident characters, which give to its structure much interest; and it is also one of great value to Man, on account of the large quantity of grateful and refreshing fruit with which it supplies him, in the very climates where it is most needed. It is remarkable as being the only tropical fruit which can be intro- duced into this country, at a cost little exceeding that of our ordinary native fruits ; and whilst it thus offers a gratification within reach of the poorer classes, it is so superior to other fruits, that it cannot be despised for its cheapness even by the richest. From the amount of duty paid upon Oranges, it has been calcu- lated that about 272 millions are annually imported ; which gives an average of nearly a dozen to each individual of the popula- tion. This abundance is due in part to the prolificness of the tree ; a single individual, at St. Michael's, having been known to produce 20,000 Oranges, fit for packing, exclusive of the damaged fruit and waste, which may be calculated at a third 398 AURANTIACE^E, OR ORANGE TRIBE. more. It is also due to certain qualities in the fruit itself, which allow it to be kept for a considerable time, with less alteration than fruit of any other kind. Of these qualities, one of the most remarkable consists in the thick spongy rind, which resists changes of temperature by its non-conducting power ; and in the large amount of minute oil-receptacles by which the surface is occupied, the contents of which almost entirely prevent the evaporation of the watery fluid within, and, by their acridity, resist the attacks of insects, &c. from without. Hence internal decay is the only accident by which oranges are liable to be destroyed ; and this does not happen for a long time, if the rind remains uninjured, so as completely to exclude the air from the interior, and if they are well ventilated, and kept free from moisture, which would cause the exterior to decompose. 564. If we examine any plant of the Orange tribe, grown in a hot-house in this country, or in the open air in its native clime, we may at once observe that it has a peculiar aspect, in consequence of the surface of its leaves being covered with minute yellowish dots. These dots are little receptacles for secretion, filled with an essential oil very fragrant to the smell, though acrid to the taste ; the leaves possess some fragrance in their natural state, but, if they be crushed between the fingers, this is very much increased, part of the receptacles being then ruptured. These little cavities exist not only beneath the surfaces of the leaves and fruit, but also in the leafy parts of the flower, which owes most of its fragrance to them. On further examining the leaves, it will be observed that they are articulated or jointed at the junction of the blade with the petiole, and that the latter is expanded (more or less in the different species) into a sort of small supplementary leaf, by the development of a narrow blade from each side. In some species the leaves are pinnate ; and it occasionally happens that the leaflet of one side only is deve- loped, or that even both are absent ; so that the petiole, which is then much enlarged, has to perform the functions of the true leaf, as in some other cases (. 228). The calyx has the shape of a cup, being formed of five sepals (in some species only three) united at their lower portion, and separating above into as many AURANTIACEjE, OR ORANGE TRIBE' 399 teeth ; it early falls off. The petals are equal in number to the sepals ; they are sometimes slightly adherent at the base ; and in the Orange they are fleshy and white, with dots of green. The stamens are equal in number to the petals, or are twice, or some multiple, of their number ; the filaments are rather flattened at the base, and are sometimes adherent into one bundle, sometimes into several, and are sometimes altogether free, as in the Orange itself. The pistil has a nearly globular ovarium, composed of several adherent carpels ; it bears a thick tapering style, having a slightly-divided stigma at its point ; and in each cell of the ovary there is a double row of ovules. FIG. 149. CITRUS AURANTWJM. a, Flower ; i; stamenu, to show the union of the hase of the filaments ; c, pistil ; d, transverse section of the ovary ; e, ditto of the fruit ; /, seed. 565. During the ripening of the fruit, however, a large pro- portion of these ovules perioh ; and in the Orange and its nearest allies, the cavity of the seed-vessel becomes filled up with a pulp consisting of separate vesicles, each containing a portion of the sweet-acid fluid, which is so characteristic of the fruit of this order. The aggregation of these cannot be distinctly seen in the usual state of the common Orange, in consequence of their close adherence to one another ; but in an over-ripe Orange, or in one grown in a hot-house, they are very easily separable. An im- portant change takes place also in the structure of the carpels themselves, which will serve to illustrate the still more striking alterations that occur elsewhere. It is to be remembered that each carpel may be regarded as composed of the same elements 400 AURANTIACE^E, OB ORANGE TRIBE. which form a leaf ; and that in some carpels, the resemblance to a leaf is very distinct (. 462). Supposing the two edges of the carpellary leaf to be folded together, as represented in Fig. 97, we should have the cuticle of the under surface becoming the lining of the cavity, the cuticle of the upper surface forming its external wall, and the parenchyma or fleshy tissue of the leaf intervening between them. The amount of this parenchyma is subject to much variation ; and the two cuticles often undergo great changes in structure and degree of density. The ovarium of the Orange is to be regarded (as already stated) as made up of a considerable number of carpels adherent to each other ; and in its early condition, the walls of these are everywhere of the same firm fleshy character. During the ripening of the fruit, however, the rind or external wall is separated from the inner wall by a quantity of spongy parenchyma, which in some species (as the Shaddock) attains a very considerable thickness ; the outer walls of all the carpels unite together to form one conti- nuous envelope ; whilst the inner walls, enclosing the pulp and seeds, are easily separated from this and from each other. In the Plum, Cherry, Peach, and other stone fruits, which belong to the order Rosaceas, the change is still more decided. In these, each fruit, which is the ripened ovary, contains but one cell ; and each cell usually includes but a single ovule when mature, though at an earlier period it may have contained several. Now th* lining or inner wall of the ovary here becomes greatly con- densed, forming the stone; the outer membrane continues to exist as the cuticle or skin of the fruit ; and it is the fleshy part of the carpellary leaf, very much increased in amount, that forms the edible portion. In such instances, the outer is called the epi- carp, the inner wall or stone the endocarp, and the succulent flesh the sarcocarp. 566. The various species of the Orange tribe are almost all natives of the East Indies and China, whence they have been transported to other countries within or near the tropics. They nearly all contain sugar, citric acid, an aromatic essential oil, and a bitter principle having tonic properties; but these are combined in varying proportions in different fruit. Thus in the AURANTIACE^, OR ORANGE TRIBE. 401 common Orange the sugar prevails, and the acid (when the fruit is ripe) is subordinate. In the Lemon, the acid is always predominant in the pulp, and the oil is more abundant in the rind. In the Shaddock, and still more in the Seville Orange, the bitter principle manifests itself. Various species, unknown in this country, are used as articles of food by the inhabitants of the countries of which they are natives; and from some a valuable timber is derived. The Orange and its allied species require two years to mature their fruit ; and, as they continue flowering all through the summer, a healthy tree exhibits, during a considerable part of each year, every stage of the pro- duction, from the flower-bud to the ripe fruit, in perfection at the same time. Most of the oranges and lemons intended for transportation to a distance, however, are gathered whilst they are still green ; for if the fruit were allowed to become mature, it would spoil in the conveyance. The gathering of oranges and lemons for the British market generally occupies from the beginning of October to the end of December ; and they would require to hang until the commencement of the spring, to ripen fully on the tree. It is remarkable that the Orange trees from which the fruit is gathered green, bear plentifully every year ; whilst those upon which the fruit is suffered to ripen, afford abundant crops only in alternate years. The Oranges of St. Michael are the best that are known in Europe ; but the tree was introduced there by the Portuguese, as it was by the Spa- niards into the New "World. The Orange is extensively culti- vated in Spain and Portugal, where it was early introduced by the Moors ; near Cordova there are trees which are considered to be 600 or 700 years old ; and in Andalusia there are exten- sive orchards, which have formed the principal revenue of the monks for ages. In the south-east of France, also, and in the North of Italy, the orange is cultivated with great success ; but it does not thrive well in the peninsular part of the latter coun- try, except at the South. Besides the refreshment afforded to Man by the cooling fruits and delicious perfume characteristic of this order, it yields him an article of great importance in his manufactures, lemon juice, the chief uses of which have been formerly mentioned ( 402). 402 AMPELIDR&:, OR GRAPE TRIBE. 567. The next order to be noticed is that of AMPELIDE^E, which is principally important as containing the common Grape Vine, which will serve as an illustration of its characteristic structure. Nearly all the plants of the group are climbers, and most of them support themselves by tendrils. The nature of these organs differs, in almost every tribe of plants which pos- sesses them. If the Pea be examined, its tendrils will be seen to consist in a prolongation of the midrib or central stalk, from each side of which the leaflets arise. In some plants, this office is performed by the prolonged tips of the petals, which twine round any object in their neighbourhood that can afford them support. In the Vine, the tendrils are developed from a num- ber of supernumerary barren flower-stalks. The flowers of the Vine grow on short stalks, which diverge from others, and these branch from the central stem ; in this manner, when the fruit is ripe, a cluster is formed, differing considerably from that, in which the fruit-stalks at once proceed from the stem, as they do in the Currant. The former arrangement is called a panicle, the latter a raceme. The calyx is very small and almost undivided, ... Fio. 150. PORTIONS OF THE FLOWER OF COMMON VIWE. A, flower opening ; a, calyx , fc, corolla, the petals detached at the bottom but united at the top; c, stamens; d, glands. B, ovarium surrounded by the stamens. C, vertical section of ovarium, show- ing its two cells and ascending ovules ; a, calyx ; b, origin of petals ; c, glands ; d, stigma. D, horizontal section. E, section of ripe fruit. looking like an expansion of the disk ; within it are seen, in the bud, five petals which hold together at the point, though sepa- AMPELIDE.E, OR GRAPE TRIBE. 403 rate at the base ; and these are afterwards detached and carried upwards by the extension of the stamens. The stamens are five in number, opposite to the petals ; there is, therefore, a whorl deficient (. 465) ; and the abortive rudiments of this we find in five little glands projecting from the disk, which alternate with the fully-developed stamens. Within the circle of stamens is found a two-celled ovarium, surmounted by a single stigma, which is not supported upon a style, but seated at once upon the ovarium ; hence it is said to be sessile. In each cell are two erect (. 500) or ascending ovules. The fruit is, as is well known, a succulent berry, with from one to four hard seeds contained in its pulp ; the original division into two cells is nearly oblite- rated, when the fruit is ripe. An additional character which may be remarked in the common Vine and its allies; and which is interesting as showing the affinity between this order and the succeeding one, is the tendency to a swelling or tumi- dity, in the branches, near the points from which the leaves proceed ; and in the Vine, the young branches have the divi- sions into nodes marked nearly as strongly as they are in the Grasses (. 148). 568. The plants of this group are naturally inhabitants of the milder and hotter parts of both hemispheres, especially of the East Indies. There is a very close resemblance in essential characters amongst them all ; though in subordinate peculiari- ties the tendency to variation is considerable. The mode of growth, and the form of the leaves, are nearly the same through- out ; and the chief obvious difference is in the size of their flowers, which are usually greenish in colour, and in the taste of their fruit. In the Fox-grape of America, for instance, the berries have a vile indescribable taste, which has been compared to the odour of the fox ; in the River-grape, they are small, black, and acid, but the flowers have a delicious odour, which makes amends for their minuteness. The genera Cissus, and Ampelopsisy many species of which are well known as creepers (the most common of which is the Virginian Creeper), differ from the Vines in having the leaves divided into five distinct segments; and they are remarkable for the rich crimson hue 404 AMPELIDE^:, OR GRAPE TRIBE. which these assume in autumn. Some species of these possess astringent properties, in addition to the ordinary acid of their fruit ; and in the Virginian Creeper there is a considerable amount of acid in the leaves, which causes them, when bruised and applied to the skin, to raise blisters. Hence, these plants have been used medicinally in some countries; but not with any peculiar advantage. 569. Few plants have been more cherished, and more vitu- perated, than the Vine. It must be confessed that, if mankind could abstain frcm the abuse of its products, there is no tree that affords more acceptable or refreshing fruit ; but the abuse has been so prevalent wherever the use has extended, and its consequences have been so pernicious, that it may be questioned whether the evil dispositions of Man have not turned that to a curse, which the Bountiful Creator certainly intended as a bless- ing. The cultivation of the common vine, which is not native to Europe, but which now grows wild near the coasts of the Caspian Sea, in Armenia, &c., and which probably extended, at an early period of the history of Man, over all parts of the earth then tenanted by him, may be traced to a very high antiquity. Its growth, and the preparation of wine from it, were probably branches of antediluvian history ; for we read that, immediately after the Deluge, Noah planted a vineyard, and drank of the wine, even to intoxication ; so that the sin of habitual drunken- ness is likely to have been one of those, which led to that signal manifestation of the Divine displeasure. From Egyptian tra- dition, the culture of the vine appears to have been practised in that country, at the earliest period of its settlement. It was gradually spread, with the progress of civilisation and of inter- course between nations, from its native habitation in Central Asia, to Greece, Sicily, and Italy; and thence to Portugal, Spain, and France. Its introduction into Britain seems to have been due to the Romans ; but the average temperature of this country is too low for its successful cultivation in the open air. With the assistance of artificial heat, however, aided by rich manure, and trained by horticultural skill, the vines grown in this country have surpassed ail others in the size and luscious- AMPELIDEjE, OR GRAPE TRIBE. 405 ness of their fruit. It has &ot been found generally worth while, however, to make wine from the juice of British grapes ; since those produced in hot-houses are by far too valuable for such a purpose ; and those grown without artificial heat do not contain enough sugar, to enable the fermented liquor to rival that obtained from the vineyards of warmer climates. Some centuries since, however, when foreign wines were less readily obtainable in Britain, large quantities of wine were made in the southern part of our island. Even so late as the year 1763> sixty pipes of wine resembling Burgundy were made from the produce of a vineyard belonging to the Duke of Norfolk, near Arundel Castle on the south coast of Sussex ; and at the present time there are still two or three vineyards near the south coast of Devon, from which wine in small quantities is commonly made. 570. The culture of the vine as an article of husbandry extends over a zone stretching from about the 21st to the 50th degree of north latitude, and consequently about 2000 miles in breadth ; and reaching in length from the western shores of Portugal to the North of India. The best wines are made about the centre of the zone ; those of the north being harsh and austere ; whilst the juice of the grapes of the south too soon passes into the acid fermentation, so that they are better adapted for being dried as raisins. Hence in Spain and Greece, the vine- yards of the higher grounds produce the best wines ; whilst the grapes produced upon the low hot shores have always to be dried. On the other hand, in Madeira and the neighbouring islands, in which the near proximity of the sea on every side tends to prevent intense heat, some of the most highly-prized wines are produced, although they are much nearer the southern border of the zone. " A vineyard, associated as it is with all our ideas of beauty and plenty, is in general a disappointing object. The hop plantations of our own country are far more picturesque. In France, the vines are trained upon poles, seldom more than three or four feet in height. In Spain, poles for supporting the vines are not used ; but cuttings are planted, which are not permitted to grow very high, but gradually form thick and stout stocks. 406 AMPELIDILE, OR GRAPE TRIBE. In Switzerland, and in the German provinces, the vineyards are as formal as those of France. But in Italy is found the true vine of poetry, ' surrounding the stone cottage with its girdle, flinging its pliant and luxuriant branches over the rustic verandah, and twining its long garland from tree to tree.' It was the luxuriance and the beauty of her vines and olives, that tempted the rude people of the North to pour down upon her fertile fields. In Greece, too, as well as Italy, the shoots of the vines are either trained upon trees, or supported, so as to display all their luxuriance, upon a series of props. This was the custom of the ancient vine-growers; and their descendants have preserved it in all its picturesque originality. The vine-dressers of Persia train their vines to run up a wall, and curl over on the top. But the most luxurious cultivation of the vine in hot countries, is where it covers the trellis- work which surrounds a well, inviting the owner and his family to gather beneath its shade. 4 The fruitful bough by a well ' (Genesis xlix. 22) is of the highest antiquity." 571. The vine lasts to a considerable age; it spreads also to a large extent, or when supported, rises to a great height. Although it bears plentifully at three or four years, it is said that vineyards improve in quality till they are fifty years old. In France and Italy, there are entire vineyards still in existence, and in full bearing, which were in the same condition at least three centuries -ago. Many vines in this country are above 100 years old. A vine existed at Northallerton, in 1785, which covered a surface of 137 square yards, and the principal stem of which was about 15 inches in diameter; it was then about 100 years old, and it increased in size afterwards, but it is now dead. There is at present a vine grown under glass at Hampton Court, which covers a surface of 22 feet by 72, or 1 694 square feet ; this bears seldom less than 2000 clusters every season ; and in 1816 there were at least 2240, each weighing on the average a pound. Vine-growers enumerate nearly 300 different kinds of grapes, which are all, whether black, white, blue, or varied in colour, but varieties of the same species. The quantity of foreign wine of various descriptions imported into Great Britain AMPELIDE.E. OB GRAPE TRIBE. GERANIUM TRIBE. 407 in the year 1839, was nearly ten millions of gallons ', from which the revenue derived a duty of nearly two millions sterling. The quantity of raisins imported was about ten thousand tons, the duty upon which amounted to 135,000/. An article still more largely imported, is known under the name of " Zante currants;" of these, which are really small dried grapes grown in the Ionian Islands, the importation was in 1839 to the amount of more than ten thousand tons, the duty on which was nearly 190,000^. These facts will serve to show the vast extent over which the vine must be cultivated, in order to yield, to Britain alone, so large an amount of valuable products. Order GERANIACEJB, or Geranium Tribe. 572. This order is chiefly interesting on account of the large number of species which are natives of Britain, and the amount of other kinds which are now naturalized here, being cultivated for their showy and elegant blossoms. What are commonly termed Geraniums by the horticulturists are not really such, but belong to the allied genus Pelargonium. Of the real Geraniums, some species or other may be found growing wild almost every- where, and are commonly known by the name of Cranesbill, which they have received on account of a peculiarity that will be presently noticed. If we examine almost any kind of Gera- nium, we shall find that, as in the last order, the stems are tumid at the points from which the leaves arise ; a character which seems of slight importance, but which often runs through a particular Natural group, and enables us to easily recognize the plants belonging to it. Several flower-stalks very commonly diverge from one centre (in the same manner as do the metal stretchers, by which the whalebones in an umbrella are spread asunder,) forming what is called an umbel; but in most of the British Geraniaceae, each principal stalk bears but two flowers. The calyx consists of five ribbed sepals, which spread asunder when the flower is open ; but when the petals have fallen off, they contract again around the young and tender ovaries, to which they then form an efficient protection. The petals are 408 ORDER GERANIACE^, OR GERANIUM TRIBE. also five in number, except in a few instances in which one is undeveloped ; their veins are unusually prominent, and they give to the petals a streaked or pencilled appearance. These veins consist almost exclusively of air-vessels, and they serve as beautiful objects of microscopic investigation. The stamens are usually two or three times the number of the petals ; in the Geraniums there are ten, and they distinctly form two rows, of which the outer one is shorter than the other ; and in the Ero- dium or Cranesbill, also a British genus, the stamens of the outer row do not bear anthers. In the cultivated Geraniums, or Pelar- goniums, the corolla is somewhat irregular, the two upper petals being larger than the three lower, and standing apart, so as to give the flower the appearance of having two lips. The pistil of the Geranium tribe has a singular structure. It consists of five carpels clustered together round an axis, which is the disk pro- longed upwards through their centre in each cell of the ovarium is a single seed. The styles adhere together in such a manner as to form but a single column, divided at the top into five lobes, which are the stigmas. (Fig- 151). 573. When the fruit is ripe, it resembles in a striking manner the bill of certain birds ; whence the British Geraniums are known by the name of Cranesbill ; and the Erodium (an allied genus) by that of Storksbill. This singular appearance is owing to a very simple circumstance. In most plants, the styles shrink up or fall off, at the same time that the flower fades ; and, by the time the fruit is ripe, they have entirely disappeared. But in the Geranium the styles continue to grow and harden as fast as the fruit itself; and when the latter is ripe, the styles project from the ovaries in the form of a beak. At the time that the fruit is ripe, the seeds are sown in a very curious manner. The carpels and styles are still clustered together round the central axis ; but the latter shorten in drying ; and as they adhere so closely at their points that they cannot separate there, they actually cause the separation of the carpels at their base ; and these, when torn up as it were by the roots, curve towards the top of the style, and at the same time open by the face which was previously adherent, so as to let the seed drop out. This ORDER GERANIACEJE, OR GERANIUM TRIBE. 409 action takes place suddenly: and it may be noticed in any common Geranium whose fruit is ma- ture, if gathered before the dew is off and then put in the sun ; the effect of its heat will be to detach first one and then another carpel with a snap- ping sound, the jerk serving to scatter the seeds. This peculiar mode of separation is common to the whole order, and is very characteristic of the plants in- cluded in it. 574. FIG. 151 STRUCTURE OF FLOWER OF MEADOW GERANIUM. _, A, stamens and pistil ; B^the lower part of the pistil, showing the clustered carpels; C, section of the pistil, showing a, raniaCPEB are exten- the ovule > and b > the prolonged axis, round which the carpels are clufitered, and which forms the hard beak in the ripe sively diffused OVer fruit. D, a couple of ripe fruit, enveloped in the calyx +1-.P rrlnV>P rmp below ' the st y les projecting above ; a, is a carpel which has ^iuue, c been detached by the hardening and contraction of its style. genera being re- stricted to one quarter, and others to a different part. The chief residence of the Pelargoniums is at the Cape of Good Hope, from which all the showy Geraniums (so called) which ornament our windows and gardens, have been derived. These have been greatly improved by cultivation, and many new varieties have sprung up ; and their number has been still further extended by hybridism, which can be very effectually performed in this group, the offspring almost always pre- senting a complete intermixture of the characters of its parents. Thus, if we take the pollen of a plant with red flowers, and place it upon the stigma of one which has white flowers, the 410 ORDER GERANIACEJE, OR GERANIUM TRIBE. seed will produce a plant having light-red flowers ; or if we cause a sort with large unsightly flowers to intermix with one having small neat flowers, we shall probably obtain a variety having large flowers that are as neat in appearance as those of the small flowered kind. This intermixture will only take place, however, among varieties of the same species, or among species nearly related to each other ; there are some Pelargo- niums which will not hybridize together ; and the Pelargonium is not fertile with the Geranium. The Geraniaceae are not marked by any very active properties ; they possess, however, some astringency, and also an aromatic resinous principle. The stem of a foreign species of Geranium burns like a torch, and gives out an agreeable odour. The root of an American species is considered a valuable astringent, and is known by the name of Alum root. The British species commonly termed Herb- Robert, is held in repute for its medicinal virtues in some parts of the country. 575. Very nearly allied to the Geraniacese is the small order TROPJEOLE^E, of which the members are all natives of tropical America, but of which one species is now commonly naturalised in our gardens under the name of Nasturtium (which is, how- ever, an incorrect one), sometimes abbreviated into Sturtion, or occasionally Trophy-cress. The common name refers to the similitude it bears in taste, smell, and general properties, to the true Nasturtia or Cresses ; a similitude so great, that the same insects resort to and feed on both. The plant is cultivated in Bri- tain for the sake of its unripe ovaria, which possess an agreeable pungency of flavour, and are pickled to be used like Capers as a sauce to boiled mutton. This order differs from the last, chiefly in the following particulars. The sepals of the calyx are un- equal in size, and one of them is provided with a long distinct spur (of which a rudiment, however, may be traced in Pelar- gonium) ; this is subject to great varieties of form ; indeed a series of monstrosities, such as may often be easily collected from a single bed of these plants, presents many curious phenomena. There seems a great tendency towards the return to a regular form, by the equalisation of the sepals ; in some instances the STURTION TRIBE. BALSAM TRIBE. 411 spur will be found nearly or altogether deficient; whilst in others it would be double or triple, the three being sometimes united, sometimes divergent from each other. In one curious specimen which came under the Author's notice, a second spur grew from the first, not downwards, however, but upwards into the flower, just as if we push back the finger of a glove, so as to project into the part that receives the hand. The petals are also more or less irregular, three being smaller than the rest, and these being occasionally undeveloped. The stamens are eight in number, and are perigynous or adherent to the calyx (. 498). This, then, is an instance in which an exception occurs to the character that has been taken as the chief guide in classification ; for although the perigynous stamens, considered in themselves, would cause the order to be removed into the next class, yet its affinity with other Thalamiflorae, and especially with Geraniacese, is so manifest, that it cannot be properly re- moved from that group. The ovary is made up of three carpels, adherent as in the last order, around a central elongated axis ; these each contain a single seed. 576. Another allied order is that of BALSAMINKE, the Balsam tribe ; this has not, however, any of those medicinal virtues which might be inferred from its name, but consists only of a small number of plants, which are esteemed for the beauty of their flowers and their elegance of aspect. Of these, one species is a native of Britain, though it is rarely found wild ; and this is remarkable for the curious manner in which its seed-vessel opens (. 419). There is greater irregularity in the flower than in either of the last two orders ; so that the nature of its parts might not be understood at first sight. The sepals are five in number, but unequal and irregular in form ; the two upper and inner ones are adherent, while the lower one is spurred. There are only four petals ; and these are adherent in pairs ; so that the corolla appears as if it consisted of two only. The stamens are five in number, and their position is regular ; so that, by comparing their places with that of the petals, it becomes evident that each of the apparently-single petals consists of two, and that a fifth petal, which should occupy the space between them, EE2 412 ORDER OXALIDE^E, OR WOOD-SORREL TRIBE. is undeveloped. The ovarium is made of five carpels clustered together, their cavities remaining separate ; the stigma is sessile on its top, as in the Poppy (. 523), and exhibits a greater or less division into five parts. The Balsams usually grow in damp places among bushes ; and one or two species are found in nearly every quarter of the globe. 577. Another small order, allied to the Geranium tribe, is that of OXALIDE^E, or Wood Sorrel tribe ; which is chiefly de- serving of notice, on account of an important product yielded by some of its species. The Wood Sorrel (Oxalis) and its allies are herbaceous plants, which abound most in the warmer tem- perate regions, especially in America and at the Cape of Good Hope; but two species are found in the woods and shady places of this country. In the structure of their flowers, they differ but little from Geraniaceae ; their calyx and corolla each con- sisting of five equal leaflets ; their stamens being ten in number, arranged in two rows, of which the outer one is the longest ; and their ovaria consisting of five adherent carpels. The stamens are generally united at the base, however, into a single FIG. 152. DIAGRAM OF THE FIXHVER OF Ox- , ,, ., , AMDK^E. bundle ; there is no central axis in the midst of the carpels ; the styles are distinct ; and there is a minute but im- portant difference in the structure of the seed. They are further distinguished by the division of their leaves, which are generally compound ; and, if simple, become so merely through the want of development of some of the segments. In this group, as in the Balsaminese and Geraniacese, there is a provision for the scattering of the seeds by the sudden rupture of their integument, which possesses elasticity enough to expel them with some force. The Wood-Sorrel is one of the plants whose leaves droop very evidently at night. The property which is most characteristic of the Oxalideae is the acid nature of their juices, which is chiefly to be noticed in the common Wood Sorrel of this country. The ORDER OXALIDEJ3, OR WOOD-SORREL TRIBE. 413 acid is peculiar in its properties, and is named oxalic from its existing in this plant, from which, indeed, it was at first ob- tained. Its uses in the arts have already been noticed (. 401). The quantity obtainable from this and other plants which furnish it, is too small for the supply of these; since, from twenty pounds of the leaves of the Wood Sorrel, which yield about six pounds of juice, not quite three ounces of oxalate of potash can be obtained. Since, therefore, it has been ascertained that the acid might be obtained pure by the action of nitric acid upon sugar, this mode of producing it has been generally adopted, except in places where the plant is very abundant. One Indian subdivision of this tribe differs from the rest, in the larger size of the species belonging to it, which grow into bushes or even trees; and some of these are cultivated for the sake of the juices afforded by the leaves, flowers, and fruit, which are of a pleasant acid character, and are esteemed as cooling remedies in fevers. One species, moreover, is remarkable for the great irri- tability of its leaves, which perform movements resembling those of the Sensitive Plant ; and there is a foreign species of Oxalis, that has in some degree the same property. 578. The last order of Thalamifloral Exogens to be here noticed is that of RUTACE^E, the Rite tribe, of which several species are cultivated in our gardens, though none are originally natives of this country. All the plants of the order are remark- able for their powerful odour, which is usually of a nauseous character ; and this is due to the quantity of essential oil, secreted in little cavities beneath the cuticle of the leaves, the place of which, as in the Orange tribe, is marked by half-transparent dots. To this group belongs the Fraxinella, formerly mentioned (. 374) as rendering the surrounding air inflammable in warm weather, by the quantity of this oil which it diffuses through it. The com- mon Garden Rue will give a very good idea of the structure characteristic of the order. The parts of its flower, however, are arranged in fours ; whilst those of other species are disposed in fives. The calyx consists of four sepals diverging widely from each other ; and within these, alternating with them, are four petals. The stamens are eight in number ; and they arise from a 414 ORDER RUTACE^E, OR RUE TRIBE. fleshy ring surrounding the ovary. Upon this ring is seated the ovary, which consists of four carpels united into one mass. These do not stand upright, however, as they usually do ; but spread FIG. 153. GARDEN RUE. A, magnified flower deprived of petals; a, fleshy ring from which the stamens arise ; B, section of ovarium ; a, the gynobase ; 6, the placentae. C, a sjcd-vessel after bursting; a, the gynobase. away from each other at the base, being arranged on the sides of a conical disk, which rises up between them, but is not continued into the style. This disk is termed the gynobase, or base of the female organs (.484.) The style is single, being formed by the adhesion of those of the several carpels ; but it separates at the top into four stigmas. The seed-vessel, when ripe, splits into four valves, leaving the thick hard gynobase in the centre. The number of seeds contained in each varies considerably, but is almost always less than that of the ovules. In the common Rue, there are about four ovules in each cell ; but only one of these is developed into seed. In others the ovules and seeds are more numerous. One genus (Correa) of this order presents an inte- resting anomaly, of a similar character to that which has been mentioned as occurring in the order TropceolecB ; the petals cohere together into a tube, so that the plant is really Monopetalous ; ORDER RUTACE^E, OR RUE TRIBE. 415 but it is not placed in that division of the group, since in its general structure it is so closely allied to the Rutaceae, that it cannot be separated from them. 579. The principal habitation of the Rue tribe is the South of Europe, whence it extends through the temperate portion of the Old World, rarely advancing within the tropics. The common Rue was formerly much esteemed in medicine ; it was mentioned with approbation even by Hippocrates, and for many centuries it was considered a preventive of contagion, and was known under the name of " herb of grace." It is now, how- ever, seldom employed, except by village doctresses. 580. The following table* will be found to express, in a con- cise form, the most evident points of difference among such of the foregoing orders as contain Plants found in Britain ; so that the Student will have little difficulty in assigning to its correct place a specimen of any one of them, which he may meet with. It is to be remembered, however, that there are orders of minor importance, which are not altogether excluded by these characters, and that the specimen may belong to some of them. But as all those which include the commonest wild and garden flowers have been adverted to, this is not likely to happen. CLASS EXOGENS. SUB-CLASS THALAMIFLOR.E. Flowers possessing calyx and corolla, the latter composed of distinct petals. Stamens, as well as petals and carpels, arise at once from the disk ; except when sometimes slightly adherent to the sides of the ovary. A. Stamens more than 20. a, Ovary superior. a, Leaves without stipules. Carpels distinct Ranunculaceae , 504. Carpels united ..... Papaveracece, 523. * By the use of such a table as this, almost any British plant may be referred, with great facility, to its proper Order in the Natural System. For example, we 416 #, Leaves with stipules. Calyx imbricated ..... Cistacea, 536. Calyx valvate. Stamens monadelphous . . . Malvaceae, 546. Stamens distinct . . . . Tiliacece, 557. 6, Ovary partly inferior ...... Nyrnphaceae, 520. B. Stamens less than 20. a, Leaves with stipules; carpels consolidated, o, Placentae parietal. Leaves unfolded from spiral coil ' . . Droseraceee, 540. Leaves unfolded straight . . . Violaceae t 538. )9, Placentae in axis. Fruit with beak . . ... Geraniacea, 572. Fruit without beak. Stamens monadelphous ... Qxalidece, 577. Stamens opposite petals . . . Ampelidece, 566. b t Leaves without stipules. o, Carpels distinct, anthers with valves . . Berber idea, 519. )8, Carpels consolidated. Placentae parietal, stamens tetradynamous . Crucifercs, 529. Placentae in axis, stamens not tetradynamous. Styles distinct. Capsule one-celled, with free central placenta Caryophylleae, 541. Capsule many-celled . . . Linacece, 543. Styles united, leaves dotted . . . Rutacea, 578. pick in our walk through a lane a specimen of the common duckweed, or Stitch- wort. The veined structure of its leaves, the prevalence of the number five in its flowers, and its general aspect, prevent any doubt that it is an Exogen. On examining the structure of the flowers, we at once perceive that the stamens are hypogynous ; for we may pull off both calyx and corolla, without detaching them from the disk, on which they are separately inserted. The plant belongs, there- fore, to the sub-class Thalamiflorae. The stamens may be from five to ten in number; it is comprehended, therefore, in the second division (B) of the table. Its leaves are readily seen to be without stipules, and we consequently look for it in the group of orders below b. On examining the carpels, they are seen to be consolidated; and, on cutting across the ovarium, the placentae are found to bo central; it must, therefore, belong to one of the three lowest orders in the table. It cannot be a Rue, since its leaves are destitute of glandular dots; it must, therefore, be either one of the Linaceae or of the Caryophylleae ; the most obvious difference between which is usually in the structure of their calyx, as formerly explained (. 543); but the most constant difference is that which is specified in the table as existing between their fruit. When the plant has thus been referred to its proper order, the whole of the general account given of that order will be found applicable to it, and to other species closely allied to it. 417 SUB-CLASS II. CALICIFLOR^E. 581. It will be remembered that, in this division of the Exogenous Phanerogamia, the sepals of the calyx are always adherent to each other, and that the petals and stamens appear to arise from them, rather than from the disk or receptacle, to which they may really be traced. Taken as a whole, this divi- sion cannot be regarded as containing a number of species, of essential service to Man, equal to that which has been shown to be comprehended within the former one; yet several orders of very great interest and importance are comprehended in it. To these it will be desirable to give our principal attention, passing over a large number of other groups with little or no notice. 582. The first order which presents itself is that of CELAS- TRINEJE, in which the common Holly is placed by many Botanists. This order is characterised by the possession of four or five sepals, united at the base, and of an equal number of petals alternating with them. The stamens, again, are the same in number, and alternate with the petals; and they are perigynous (.498) in their insertion. The ovarium is superior, and is composed of several adherent carpels ; it is partly enveloped in a large fleshy disk, and usually contains from two to four cells, each of which may include one or several ovules. The style is single, but separates at the top into two or four stigmata. The species of this order are mostly trees or shrubs, the flowers of which are not conspicuous. The section to which the Holly belongs is distinguished by having the petals in some degree adherent to each other ; and hence it has been placed by some Botanists, as a separate order, among the Monopetalae. The common Holly is one of the few British species of this order, which is pretty generally distributed over the surface of the globe. It is a very slow-growing tree, rarely attaining any great size ; its wood is much used by turners (being one of the hardest of the white woods), especially for the manufacture of the toys known as Tunbridge ware. The inner bark abounds in a tenacious sub- stance, which, when separated, is known as bird-lime, from the 418 HOLLY TRIBE. BUCKTHORN TRIBE. use to which it is put in entrapping birds. The bark and leaves are bitter, and have been used as a substitute for other analogous substances, in the cure of intermittent fevers. From the leaves of a species of Holly which is a native of South America, the inhabitants of that country make an infusion, which is employed as tea is among us ; this is known as Mate or Jesuits' Tea, and is very extensively consumed in Brazil, Paraguay, Chili, and Peru. Another species which inhabits the Southern part of North America, furnishes the Indians with a similar article, which is used by them as a medicine, and also as a draught of etiquette at their solemn councils. Another British species is the Euonymus, known under the name of spindle-tree, or prick-wood, from the uses to which it is applied. It has a wood which, without being hard, is very tough ; and this was formerly much employed in making spindles for the spinning-wheel. Now that the jenny has superseded the distaff, however, this is little used except for making toothpicks and skewers; and also by watch- makers, for cleaning delicate machinery, for which it is very well adapted on account of the fine point with which it may be worked without breaking. The second of its common names seems to render it not improbable, that it was formerly used in the manu- facture of those skewer-like pins, which were employed to hold dress together as late as the reign of Henry VIII., when the manufacture of metal pins became more general. The fruit and the bark of this tree have properties, which render them poi- sonous to most animals, and which give them purgative and emetic effects if taken by man. 583. Nearly allied to the last order is that of RHAMNE^:, or the Buckthorn tribe ; which may, however, be readily distin- guished from it by the position of the stamens, these being here found opposite to the petals, or alternating with the sepals. The structure of the calyx is also different, that of the Rhamneaj being valvate (i. e., the sepals, before expanding, having their edges in proximity with each other), whilst that of CelastrmeaE* is somewhat imbricated (the sepals overlying one another). The ovarium is partly enveloped, as in the last order, by the fleshy disk ; and this, as the fruit ripens, grows over the ovary, and ORDER RIIAMNE.E, OR BUCKTHORN TRIBE. 419 completely encloses it. The species of this order are distributed over nearly the whole world, with the exception of the arctic regions. They are mostly shrubs or low trees which are gene- rally remarkable for their spiny character ; this manifests itself strongly in the common Buckthorn of this country, and in the Christ's Thorn, which abounds in Greece and Palestine, and which has been naturalised in our gardens. The latter derives its name from the tradition that our Saviour's crown of thorns was made from it. The spines are, as formerly explained (. 307), undeveloped branches ; and a little examination of any spiny bush will make this evident, since all stages of develop- ment may be found, between the simple thorn and the complete branch. As already stated, cultivation has a tendency to do away with this character, by supplying the plant with nutri- ment sufficient to develop the buds that would otherwise be abortive. Upon the final cause, or object, of this curious pro- vision, the following excellent remarks, by an eminent Botanist, may be quoted : " In open barren tracts of country, the very circumstance of the sterility of the soil must prevent the produc- tion of many plants ; and of those which grow, few will be enabled to perfect many seeds. It is necessary, therefore, to protect such as are produced from extermination by the brows- ing of cattle ; otherwise not only would the progeny be cancelled, but also the present generation would be cut off. And what more beautiful and simple expedient could have been devised, than ordaining that the very barrenness of the soil, which pre- cludes the abundant generation by seed, should at the very same time, and by the very same means, render the abortive buds a defensive armour to protect the individual plant, and to guard the scantier crop, which the half-starved stem can bear ?" s 584. The inner bark and fruit of most species of this order are possessed of active purgative powers ; and some of them are also emetic and astringent. The syrup made from the juice of the berries of the common Buckthorn, was formerly much used in medicine ; but, as its operation is attended with much dis- comfort, it is now seldom employed except for administration to dogs. The berries afford, however, a valuable colouring matter, 420 BUCKTHORN TRIBE. TEREBINTH TRIBE. which is used in dyeing. The " French berries" of the shops, from which a beautiful yellow is obtained, are the unripe fruit of this plant ; and from their juice, when they are ripe, the colour termed sap-green is prepared. Another species affords the colour with which yellow morocco leather is tinged. The fruit of a species allied to the Christ's Thorn, however, contains a large quantity of gummy matter, without any substance pos- sessing active properties ; this, which is known under the name of the fiyubf) is a favourite dessert in Italy and Spain, either when fresh, or when dried as a sweetmeat ; and lozenges made from it are much employed in this country as a remedy for coughs. The Lotus, the fruit of which has been celebrated from the time of Homer, also belongs to this order. It is a native of Persia, and grows wild on the north coast of Africa as well as in its interior ; and its fruit is eaten by the inhabitants, wherever it grows. It is converted into a sort of bread, by drying and pounding ; and from its juice, when pressed out and mixed with water, and afterwards fermented, a sort of wine is commonly made. The leaves of one Chinese species are used for tea by the poorer classes in that country ; and another produces a sort of fruit, which is said to resemble a pear in flavour, but which is nothing else than the flower-stalk become fleshy. 585. Passing over several small orders of little importance, we come to that of TEREBINTACE^S, which contains a large number of species inhabiting tropical countries, distinguished by their resinous secretions, and, at the same time, by their poi- sonous properties. The number and arrangement of the parts of the flower differ considerably in the different sections of the order ; so that many Botanists subdivide it into three or more. The flowers are sometimes complete, but not unfrequently one or other set of organs is suppressed in some of them, so as to render the plant polygamous ( 483) ; and some species are dioecious. The sepals are from 3 to 5 in number, more or less united together, and imbricated. The petals, when present, are equal in number to the sepals ; but they are occasionally absent ; they alternate with the sepals, and are sometimes adherent to each other. The stamens are either equal in number to the TEREBINTH TRIBE ; CASHEW-NUT. 421 petals, or are twice as numerous, and are inserted at the bottom of the calyx, or around the ovary. The carpels are sometimes distinct, and sometimes adherent; but the styles are always distinct. The ovules are few in number in each carpel, and are usually solitary. Most of the species are trees or shrubs, having alternate leaves, which are usually compound. The resinous matter is chiefly contained in the bark, whence it frequently exudes naturally, or may be drawn by incisions. Gum mastic (. 377) and Chian Turpentine (. 375) are obtained from species of this order ; as are also Sumach and the Japan and Chinese FIG. 154, ANACAHDIUM OCCIDENTALS, OR CASHKW-TREE. black varnish, and probably Olibanum. The fruit is very com- monly acrid and astringent, and these qualities usually exist in some degree in the bark also. The well-known Cashew-nut of the East and West Indies is produced by a plant of this order. 422 ORDER LEGUMINOS^E, OR PEA TRIBE. Its appearance, whilst still connected with the plant, is very curious. The nut is borne at the extremity of a fleshy fruit considerably larger than itself; which is nothing else than the peduncle or flower-stalk enlarged and become succulent. This fruit, which is termed the apple, has an agreeable acid flavour, slightly astringent, and is much esteemed in the "West Indies, where the juice expressed from it is fermented and made into a kind of spirit. Between the two layers of the pericarp or ripened carpel, there is found a considerable quantity of inflammable oil, which is so acrid as to blister the skin if the fingers or teeth be used in removing the shell. The kernel abounds with a milky juice, and is much esteemed for its flavour. The juice of the nut of an allied species is of a deep black when ripe, and leaves an indelible stain if applied to linen, &c. ; so that it makes an admirable natural marking-ink. The Mango, a fruit highly prized in India, which has been naturalised in the West Indies also, is produced by another species of this order; several varieties of the fruit are cultivated, differing much in size and flavour. They vary in weight from a few ounces to several pounds ; some have a most delicious, aromatic, sweet, and slightly acid taste ; whilst in others, the resins so much abound that the flesh is ill-flavoured, and, being at the same time fibrous, has been not unaptly compared to a mixture of " tow and turpentine." The tree is a very handsome one; as is also that from which the black varnish of India is obtained. This varnish, whilst still liquid, is so acrid in its properties as to blister the skin, if allowed to touch it. A fruit much esteemed in the south of Europe, as well as among Eastern nations, is the Pistachio nut, which is the produce of one of the dioecious species; and in Sicily, a ceremony similar to the marriage of the Palms (hereafter to be described) is performed, in order to ensure the fertilisation of the seeds. Order LEGUMINOS^E, or Pea Tribe. 586. This is one of the largest and most important orders of the whole group. There are few which are more easily recog- nised, or in which greater interest is usually taken. It is ex- ORDER LEGUMINOS^E ; PAPILIONACEOUS PLANTS. 423 tremely rich in plants useful in various ways to Man. Some furnish him with a large quantity of wholesome and palatable food for himself, such as the Pea, Bean, Lentil, &c. ; whilst others afford equally nutritious food for cattle, such as Clover and Lucerne. Others yield valuable dyes, such as Indigo and Logwood ; and others again have stems which serve as excellent timber, such as Brazil-wood, Rosewood, and the American Locust-trees. From others are derived valuable medicinal pro- ducts, such as Senna and Cassia, or Gums, as that of the Acacia. Others, again, are attractive on account of their beauty, such as the Laburnums, Robinias, &c. ; and others are interesting on account of physiological peculiarities, such as the Sensitive-Plant (. 421), the Gleditsias (. 238), and the New Holland Acacias (. 228). Between all these there is a strong family likeness ; but there is every variety of size among the very numerous species which this order contains ; some being humble plants, whilst others are lofty trees. The most important point in which they all agree, is in the structure of their fruit, which is a pod or Legume; whence the name of the order is derived. A legume may be thus distinguished from all other kinds of fruit. It is a carpel which grows long and flat, and separates when ripe into two valves or halves ; it usually contains several seeds, which are attached to one angle only of the inside of the carpel. A Pea-pod is as apt an illustration as any that can be furnished ; and, by referring to Fig. 96, the mode in which the pod is formed from the carpellary leaf will be at once evident. The ovules proceeding from the thickened edges of this leaf, which are folded together, are attached alternately to the one valve and the other ; so that, when the pod is opened along the suture, or line of adhesion, (as is commonly done in shelling peas) half the seeds remain attached to each valve and lie in its hollow. The seed-vessels of all the plants of this order, how- ever, must not be supposed exactly to resemble the Pea-pod; they may be longer or shorter, larger or smaller, harder, thinner, or differently coloured, or may contain more or fewer seeds ; but they are always formed essentially upon the same plan. 587. A very large number of the order are further dis- 424 ORDER LEGUMINOS^E, OR PEA TRIBE. tinguislied by a singular arrangement of the petals, from which they have been termed Papilionaceous plants, owing to the resemblance which their flowers bear to a Butterfly at rest. Of this structure, the common Pea is an excellent illustration. If we examine its flower, we shall find a calyx composed of five small nearly equal sepals united into a short tube. The corolla is much larger, and consists of five petals, one of which greatly surpasses the rest in size, standing at the back of them, and over- wrapping them before the flower expands ; this is called the standard or vexillum. In front of this are two small petals, which stand nearly parallel with each other, converging a little at the point ; these are the wings, or alee. They are carefully folded over a boat-shaped curved part of the corolla, which is placed in front of all the rest; this part, termed the keel, or carina, is formed of two petals, which are slightly adherent at their lower edge, but which are separately inserted at their base. 588. There is considerable variety, in this order, as to the number and degree of adhesion of the stamens. The Papilionaceous division of it may be separated into those which have their stamens united, and those in which they are distinct. The former group contains all the European species, such as Peas, Beans, Vetches, Clover, Trefoil, &c. The stamens are usually double the number of the sepals (of which there are occasionally only four) ; and very commonly one of them is distinct, whilst the rest are united at their edges, as is the case in the common Pea, Vetch. &c. The division of the Papilionaceous Leguminosas having the stamens separate, contains few but New Holland species. The ovary is a tapering green hairy body, gradually narrowing into a style, which ends in a minute stigma. It is one-celled, and is to be regarded as consisting of but a single carpel ; sometimes, however, two or even five carpels are to be found in the centre of the flower. 589. In another division of the Leguminosse, containing the Senna, Logwood, Tamarind, and many other interesting species, the flowers present a much nearer approach to regularity. Their petals spread equally round the pistil, as in other plants ; and ORDER LEGUMINOS^E, OR PEA TRIBE. 425 their stamens also are spreading and separate. A degree of that irregularity in size, however, which is so striking among the Papilionacece* is here still evident; some of the petals or stamens being larger than the remainder. Few of this group are ever seen in this country ; but in foreign climes they are very abundant. 590. The third division of this order comprehends those which have flowers formed upon the plan of the last, that is, not being papilionaceous, whilst the number of stamens is much greater, being triple or quadruple that of the sepals. The flowers are extremely minute, and grow in compact clusters ; the stamens have very long, slender, and separate filaments. This is the structure of the division which includes the Mimosas, amongst which is the Sensitive Plant. Many of these have a very elegant appearance, the clusters of flowers which they bear being numerous, and often presenting gay colours. 591. Besides the peculiar structure of the fruit, in which these subdivisions all agree, the entire absence of a separate albumen, so that the cotyledons are fleshy, and occupy with the embryo the whole interior of the seed, is a character of great importance, which prevails through the whole group, and shows it to be a natural one. The number of species already known is very considerable, certainly not less than 4000 ; and many more must remain to be discovered. The order is diffused over the whole habitable globe. Some species of it have a very extensive range ; whilst others are restricted to particular coun- tries. The Papilionaceous division with united stamens contains most of the former ; but these appear to flourish best in tem- perate and moderately warm latitudes, diminishing in number towards the poles, and giving place to the Mimosa and Cassia tribes nearer the equator. 592. The properties of the different species of this order are so various, that it is difficult to enumerate them all. Their difference may also appear to invalidate the principles formerly laid down, respecting the correspondence between structure and properties (, 479) ; for, whilst some of them seem to be remark- able for nothing but the large quantity of tasteless gum which 426 ORDER LEGDMINOS43, OR PEA TRIBE. they contain, others are violently irritant, and others strongly astringent. The seeds of the common Laburnum, for example, of which the flower and the pod very much resemble those o the Pea, are violently emetic and purgative, and have proved absolutely poisonous to children. The seeds of other species are very bitter, and are valued in India for their tonic virtues. The character of the juices which may be extracted from the wood, is equally various. This apparent exception, however, does not really weaken the principle ; since the number of points of dif- ference among the several tribes is so great, that there can be little doubt that they might be subdivided into several orders, each of which might be characterised by properties peculiar, or nearly so, to itself. Having already adverted to some of the best known among the useful products of this order, we may here mention a few others. The pulp of the Tamarind, which is so grateful in thirst on account of the large quantity of acid it contains, lies between the seeds and the valves of a legume ; as does also that of the Cassia, which has a sweetish taste, and which is useful as a mild aperient for children. Licorice is derived from the juice of the roots of the plant which yields it. The juices of other species are powerfully astringent, and are used both in medicine and in arts ; of this kind are Catechu, (. 365), Kino, and other substances. The bark of the New Hol- land Acacias has been introduced into this country as a material for tanning. The fragrant resins, called Balsams of Tolu and Peru, which are in much use for burning as perfumes, and for medicinal purposes, are the produce of a South American species. Full details regarding Indigo, one of the most valuable products of this order, have been given on a former occasion (. 388). Some species, which are found in the "West Indies and in South America, contain juices which have a remarkable power of intoxicating fish, rendering them easy of capture, without in- juring their wholesomeness as food. 593. The next order is one of nearly equal extent and importance ; and contains, like the Leguminosaa, a large number of species having the same general resemblance, yet differing in the structure of many important parts. This is the order PEA TRIBE. ORDER ROSACES. 427 ROSACE^E, or Rose tribe, to which belong not only Roses and their immediate allies, but a large part of our most valued fruits, which seem very unlike each other, such as the Strawberry and Apple, the Raspberry and Pear, the Medlar and the Almond, &c. They all agree, however, in the general plan of the struc- ture of the flower, which may be studied in almost any of the ordinary wild species. The Strawberry flower will, perhaps, at first serve the purpose better than the Dog Rose, or any of the true Roses ; on account of a peculiarity in the latter presently to be mentioned. On looking at the outside of the Strawberry flower, we observe what is apparently a calyx consisting of ten sepals ; this would be an exception to the general rule of the group, which is to have only four or five parts in the calyx ; and, on looking further, it is seen that these leafy parts are arranged in two rows, of which the lower or outer one may be considered as formed by bracts. The corolla consists of five (rarely four) equal petals ; and within these is a large number of stamens. Up to this point, then, we find nothing to distin- guish Rosacese from Ra- nunculaceae ; but, upon looking at the position of the stamens, we ob- serve that, instead of rising directly from the receptacle beneath the carpels, they seem to grow out of the side of the calyx. Hence, whilst the RanunculaceSB F IG 1S5. AGRIJIONIA EUPATORIA. a, flower, showing ,, T . the twelve stamens; 6, the five pistils. mostly belong to the Lm- raean class POLYANDRIA, the order Rosaceae nearly corresponds FF2 428 ORDER ROSACES, OR ROSE TRIBE. with the Linnsean class ICOSANDRIA ; some, however, belong to the class DODECANDRIA, as the Agrimony (Fig. 155.) The pistil of the Strawberry is very much like that of a Crowfoot ; for it con- sists of a large cluster of non-adherent carpels, each having its own style and stigma, and containing a single seed. The trans- formation of such a flower to the fruit of the Strawberry seems very strange, until the process is understood. When the corolla has fallen off, and the calyx has closed on the tender fruit, the receptacle on which the carpels are set, gradually swells, and separates them from each other, bearing them on its outside. It becomes, at last, the soft juicy fruit ; and what appear to be the seeds on its outside, are in reality the carpels, which were originally in proximity with each other, and are now dry and in close contact with the real seed-coats. The calyx remains at the base of the swollen receptacle. 594. It is principally in the number of carpels which undergo development, and in the degree in which these are united toge- ther, that we meet with variety in the structure of the flowers and fruit of this order. In the Raspberry, we find the structure of the Strawberry but slightly modified. The calyx has evi- dently here but five parts ; the petals are five in number ; the stamens are indefinite in number and adherent to the calyx ; and the carpels are numerous and distinct, and are supported upon a fleshy receptacle. In the ripening of the fruit, however, this receptacle does not enlarge, as in the Strawberry, but remains as the white hard core of the fruit ; and the fruit itself consists of the carpels, which, instead of becoming dry, acquire an increase of juice ; and it is the soft fleshy walls of these carpels, that form the succulent part in which the seeds are imbedded, and from which the core may be withdrawn. 595. If we now turn our attention to the Rose tribe, we shall find that the flower is constructed upon a plan which appears similar, until we examine the centre of it, and there we find a tuft of stigmas without any visible carpels. On looking further, however, and pressing the flower forcibly, we find that the styles rise up from the neck, as it were, of an oblong green body which, being below the calyx, looks like an inferior ovarium. ROSE TRIBE. STRUCTURE OF FRUIT, 429 On splitting this body perpendicularly it will be perceived that it is in reality the tube of the calyx, formed by the adhesion of the sepals, which closely envelops the seed-vessels, and is con- tracted into a narrow orifice at the point whence the styles arise. The ripe fruit of the Rose, known by the names of Hip, Hep, or Haw, is nothing else than this tube of the calyx, which may be regarded, perhaps, as a hollow prolongation of the receptacle, turned red and fleshy ; and in its interior will be found the carpels, changed to bony grains. The Apple and Quince, and their allies, are constructed very nearly upon the same plan. The principal difference consists in this, that the ovaries and the tube of the calyx completely coalesce, and form one body, which becomes the fruit. The eye at its end marks the point from which the calyx spreads out ; this is better seen in the Medlar. The principal part of the flesh of the Apple consists of the tube of the calyx or the prolonged receptacle ; but in its interior are found the five carpels, whose thin walls are somewhat horny. In the Medlar, these are thick and have a bony firmness. 596. In the Almond tribe, which includes the Plum, Apricot, Peach, Nectarine, Cherry, and all similar fruits, there is only one carpel developed ; and this in time changes to the fruit, which is termed a drupe, consisting of a hard shell enveloping the kernel, and itself inclosed in a soft flesh. These all agree in the peculiar properties which they derive, from the presence of a certain quantity of Prussic Acid (which, when of full strength, is one of the most violent poisons known) in some part of them, usually either the seeds, or leaves, or both. The quantity is so small as to cause no danger in making use of such parts, unless this ingredient be concentrated in any artificial mode, as it is in what is called Laurel Water, which is distilled from the leaves of the Prunus Laurocerasits, or Cherry Laurel, and is used for giving a flavour to various sweet dishes and liquors. 597. This order principally abounds in the cold and tem- perate regions of the northern hemisphere, In fact, scarcely any species of the Rose, Apple, and Almond tribes are found else- where. There is a small group, however, distinguished from the rest of the order by the constant absence of petals, which abounds at the Cape of Good Hope, where it represents the Rosacese of 430 ROSE TRIBE. MANGROVE TRIBE. Europe. Of this group (which is ranked by some as a distinct rder) the British genus Sanguisorla, or Burnet, is an example ; the Latin name of which is derived from its supposed power of stanching the flow of blood. Another British genus belonging to it is the Alchemilla, or Lady's Mantle, one species of which is common in fields and gravelly soils. This group is characterised by a greater degree of astringency, than that which usually exists in the true Rosaceae ; although many of the latter also possess this character. The roots of the Potentilla, or Cinque- foil, and of the Tormentil, have been used in tanning ; and the roots of a kind of Bramble afford a popular astringent medicine in North America. The leaves of the Sloe and other species have been used as substitutes for tea ; and the fruit of the com- mon Dog-rose and other allied species has a degree of astringeney, which renders it useful in medicine. 598. The next order which will be here noticed is that of RHIZOPHOREJE, the Mangrove tribe, which is chiefly remark- able on account of the singular mode of growth observed in the trees belonging to it. The Mangroves are tropical trees, growing on the banks of large rivers, or on the sea-coast, and even within the bounds of the ocean as far as low- water mark. Their mode of rooting consists, not like that of ordinary trees, of divisions of the stem beneath the ground, but (as it were) of arches of roots above it, so that a more extended base is formed, and a firmer hold FJ(J 156> _ MANGROVJ5 TREB . established, in the loose and swampy soil. From the summit of these overbending roots, the trunk of the Mangrove springs, as shown in the ad- ORDER RHIZOPHOREJ2, OR MANGROVE TRIBE. 431 joining figure. The calyx in this order is formed of from 4 to 13 adherent sepals ; and the petals are equal in number to the sepals, and are inserted upon them. The number of the stamens is double or triple that of the petals. The ovarium is two-celled, being formed by the union of two carpels, which have sepa- rate cells ; and each cell con- tains several ovules. But in the ripe fruit, we find but one cell and one seed, this having been developed at the expense of the others. These seeds are peculiar on account of their power of germinating whilst FrfG. 157- PARTS OF THE FLOWBR OF MAN- . . . . . GROVE. A, the fruit, seated upon a calyx of 7 et Wlthm the Seed-VCSSel. four sepals, and surmounted by two styles. phe final CaUSC Or purpose of U, a 'flower cut open, showing four petals ... ... alternating with four sepals, (the latter being this Singular provision IS CV1- **, when the circumstances under which the tree grows are considered. "Were they to be shed as seeds usually are, they would fall into the water, and be carried by the waves of the sea, or by the currents of the rivers, on the margins of which they live, far from any place that is fitted for their growth. But by the long radicle perforating the seed-vessel, the seedling plant, when dropped, becomes fixed in the swamp ; and thus forests of Mangroves are formed of vast extent, unsafe to be trodden by human foot, but over which the savage natives pass, leaping or climbing from root to root for many miles, without once daring to trust their weight upon the treacherous marshy ground. These swamps continually encroach on rivers, lakes, and seas ; for the network of roots intercepts and collects all the solid matter brought down by the rivers ; and, as a large part of this consists of decomposing vegetable matter, the Mangrove swamps are peculiarly unhealthy to human beings, who are very liable to suffer from pestilental fevers, if too long exposed to their emana- tions. "When the roots of the Mangroves in such places are left bare by the ebb of the tide, they are seen to be covered with 432 MANGROVES. ORDER ONAGRARIACE^E. oysters and other shell-fish, which cluster around them ; and hence originated the wonderful tales of the early voyagers in tropical climates, who affirmed that, in the East and West Indies, oysters, &c. grow upon trees. The properties of this order are astringent ; and the bark of several species is used, in the countries where they grow, for dyeing black with iron. 599. The succeeding order, ONAGRARIACEJE, requires notice chiefly on account of its containing several British species, among which may be mentioned the (Enothera, or Evening-Primrose, and the Epilobium, or Willow-herb. The former derives its common name from the circumstance of its beautiful yellow flower unfolding to the evening sun, but retiring with the glare of advancing day. Its scientific name, which means Wine-trap, was conferred upon it on account of the use formerly made of its roots, which were eaten after dinner (as olives now are) as an incentive to drinking ; it was originally called Onagra, or Ass- food ; and from this name, that of the order has been derived. Of the latter, a great many species exist in this country, some of which may be found in almost every hedge. They may be at once recognised by the peculiar position of the flower, which seems placed at the top of a long pod or seed-vessel, whence the scientific name (meaning upon a pod) is conferred upon it. One of the species of this, known as the Great Hairy Willow-herb, is among the finest of all our British herbs ; its stout hairy stems rising to the height of five or six feet, and being terminated by long clusters of bright red flowers. The typical genera of this order may be at once distinguished, by the prevalence of the number four in all the parts of the flower. The calyx consists of four sepals, which adhere at their lower part, so as to form a long tube enveloping the ovarium ; and they not unfrequently adhere in some degree, after they have diverged from the top of this, so that the calyx appears as if it were divided into only two portions. From the top of the tube of the calyx arise four petals ; and within these are commonly found eight stamens, each of which has a very long anther, swinging (as it were) by its middle from the summit of the filament. The pollen of this tribe is peculiar in form, the grains being triangular, and cohering to EVENING-PRIMROSE TRIBE. 433 each other by delicate threads. The ovariura, which will be found altogether below the flower, is four-sided, and contains four cells, in each of which are a great many ovules ; from this a single style arises, which mounts through the tube of the calyx, and usually separates at the top into four stigmas. The fruit is a dry capsule with four angles, separating into four valves. The seeds of the Willow-herb are remarkable for the curious provision by which they are dispersed ; each of them has a very long tuft of silk at one end, which is so light, that the faintest breeze is sufficient to buoy it up and carry it to a great distance. 600. Although several handsome species of this order abound in Britain and in other parts of Europe, it is in America that it is most predominant ; and from that continent we have derived a plant of far greater beauty than any native species, which is one of the most splendid of the foreign ornaments of our gardens during" the summer and autumn. This is the Fuchsia (pronounced Fushia), which, although at first introduced as a greenhouse plant, is now extensively cultivated in the open air, in the southern parts of Britain, and in sheltered situa- tions in the north. " Every body," it has been remarked, " has Fuchsias ; the poor weaver grows them in his window ; many an industrious cottager shows them as the pride of the little plot of ground before his door ; and even the suburban inhabitants of London speak of the beautiful Fuchsias they rear, with enthusiasm and delight." The calyx of this genus is of a deep crimson ; and the petals, which are of a dark purple, are small, and rolled up within it. The fruit differs from that com- mon to the order, in being a berry with a juicy rind, formed by the thickening of the pericarp, instead of being a dry capsule. This order has little, except its beauty, to render it interesting to mankind ; for there is not a single species which possesses any particularly useful property. The number of its stamens being invariably 2, 4, or 8, its genera are distributed, in the Linnaean classification, among the classes DIANDRIA, TETRANDRIA, and OCTANDRIA. 601. The next important order is that of MYRTACE.E, the Myrtle tribe ; in the flowers of many among which, also, we find 434 ORDER MYRTACE^E, OR MYRTLE TRIBE. the number four predominating ; but it is not the number cha- racteristic of the group. The leaves of the Myrtle and its allies are characterised by the same structure as that which has been noticed in the Orange (. 563), being studded closely with little receptacles, which contain a volatile oil ; so that, if they be held up to the light, they look as if pierced with holes closed up by a green transparent substance; and if bruised they emit a fragrant aromatic odour. In the common Myrtle, as in most of the order, the calyx consists of five sepals, which adhere so as to form a tube ; and within this, there is a corolla consisting of five small petals ; the latter, however, is absent in some species. Within the corolla, we find a considerable number of stamens, inserted on the summit of the tube of the calyx ; their number is generally a multiple of that of the sepals, and they are some- times united into bundles. The ovary of the Myrtle is divided into three cells, each of which contains a good many ovules ; on this is mounted a single style, which ends in a very small stigma. The fruit is a purple berry, very much resembling that of the Fuchsia ; but it contains only three cells instead of four. 602. In some species, however, the ovary is only two-celled, whilst the parts of the flower are arranged in fours. This is the case in the Caryophyllus^ a tree of which the unripe flower- buds are known as Cloves. This tree is a native of the Moluccas and other islands in the Indian Ocean, from which it has been transported to seve- ral parts of the continent of Asia, and also to the West Indies. It is only within a very limited range of climate, however, that the Clove ac- quires its full aromatic flavour, so as to be useful as a spice ; for even when grown in some of the larger islands near the FIG. 158. BRANCH OF CLOVE TREE, WITH FLOWERS AND BUDS. MYRTLE TRIBE ; CLOVE TREE. 435 FlG. 159.-STRUCTURB OF FLOWE Moluccas and in Codim-China, it is almost tasteless. The Clove has been known in Arabia from the earliest ages ; and it was introduced into the European market nearly 2000 years ago. Up to a comparatively re- cent period, how- ever, the source from which it was obtained was not known to Eu- TOpCanS. Early IU bud or Clove. B, the flower expanded, showing the stamens the 16th century, in four bundles. C, flower with stamens removed, showing the calyx and corolla, each consisting of four pieces. D, the Moluccas Were vertical section of ovarium. E, horizontal section of discovered by the ovarium. Portuguese, and were soon afterwards taken from them by the Dutch, who endeavoured to monopolise the growth of the Clove, and to regu- late the quantity which should be supplied, by cutting down or planting trees, according to their own supposed interests. This system more than once occasioned an insurrection among the natives, who regard the Clove-trees with great attachment, and who are in the habit of planting one at the birth of each child. Every part of the Clove-tree abounds with aromatic oil ; but it is most fragrant and plentiful in the unexpanded flower-buds, in which it is so abundant that it may be pressed from them. It is one of the few essential oils that are heavier than water. It is a very powerful stimulant ; and is sometimes employed in medicine; but its principal use is in cookery. The average annual crop of Cloves is from 21bs. to 2|lbs. from each tree ; but a fine tree has been known to yield 1251bs. of this spice in*a single season ; and as 5000 Cloves only weigh one pound, there must have been at least 625,000 flowers upon this single tree. The quantity im- ported into Britain in 1839 was upwards of 367,0001bs. 603. Several other species of this order have aromatic pro- perties, and yield products which are valued as spices. This is the case with the Pimento, the berries of which are known under the name of All- spice, from being considered to unite the flavour 436 ORDER MYRTACE.E ; PIMENTO, EUCALYPTUS. of cloves, cinnamon, and nutmegs. They yield an oil which much resembles that of cloves. The pleasant fruits called the Rose Apple and the Jamrozade of the East Indies, and the Guava of the West Indies, are the succulent berries of shrubs of the Myrtle tribe ; as is also the Pomegranate, which was originally a native of Barbary, but has now migrated to Europe. The volatile oil of Cajeputi is distilled from the leaves of an Indian species ; this has long been known as a valuable external applica- tion in rheumatism ; and, for a short time, it enjoyed the repu- tation of being a specific for the Indian cholera. The leaves of another species are used by the Malays as tea. 604. There is a remarkable division of the Myrtle tribe, in which the fruit is dry, instead of being a berry, and opens at the top. The greater part of the species belonging to it are natives of New Holland ; and amongst these may be specially mentioned the Eucalyptus or Gum-tree. This is destitute of corolla; and the calyx has the sepals adherent very closely together, so as completely to envelop the stamens. When these expand, how- ever, the upper part of the calyx separates from the lower, and is carried off upon the top of the stamens, very much as in the Eschscholtzia (. 525). The Eucalypti are distinguished for their astringency; and the tannin which they yield has been extracted from their bark, and used in the manufacture of leather. An Indian species affords an astringent extract, which has been substituted for Kino. 605. This order is almost entirely restricted to warm climates. A large number of species is found in South America and in the East Indies ; whilst, of the latter division of the group, a consi- derable proportion exists in New Holland and the South Sea Islands. The common Myrtle of this country is a native of the South of Europe ; and it is well known that this beautiful ever- green is liable to great injury, and even to be destroyed, if not carefully protected from the cold of our severe winters. 606. The order CUCURBITACE^J, or Gourd tribe, is not a large one, but it contains several species which are highly useful to Man, such as the various kinds of Melon, Cucumber, Gourd, &c. These plants are all herbaceous, and grow by twining stems, ORDER CTJCURBITACE^J, OR GOURD TRIBE. 437 which are furnished with tendrils. The flowers are very frequently monoecious or dioecious ; but they are sometimes complete. The calyx and corolla are usually small ; the former (as in the Cucum- ber) is not unfrequently absent; and the latter in most cases assumes the appearance of a calyx. Their parts are five in number, as are also the stamens, which very commonly adhere into a tube inclosing the style. The ovarium consists of three or five carpels united together ; these are enveloped by the prolonged receptacle or fleshy tube of the calyx (just as in the Apple, . 595). The ovary, however, has only one cell, the partitions between the carpels having been obliterated ; but in this single cell we mav readily see, on cutting across a Cucumber, that the ovules are arranged on three lines which pass up the sides, and which are, therefore, parietal placentas like that of the Heartsease. It is curious that, in the Melon and Cucumber, which are usually regarded as dioecious species, the development of staminiferous or pistilliferous flowers should be entirely governed by the degree of heat to which the plants are exposed ; the former being produced when the proportion of heat to light has been considerable, and the latter under contrary circumstances. The plants of this order are almost entirely natives of hot climates, and can only be grown elsewhere under a considerable amount of arti- ficial heat. 607. Although we are commonly accustomed to consider Melons and Cucumbers as quite free from injurious properties (except in causing indigestion in weak stomachs), this character does not extend to the whole order. The bitter purgative drug termed Colocynth is obtained from the pulp of a sort of Gourd, which is a native of the Levant, Arabia, &c.; and from the Momordica Elaterium, or Spirting Cucumber, a still more active preparation has been obtained, a few grains of which are so violent in their operation as even to destroy life. This bitter purgative principle is not absent in the common edible fruit, but is present in smaller proportion. Besides furnishing palatable food, this order is very useful to man in supplying him with vessels of various forms and sizes. Some gourds are nearly globular in form ; and the rind, when the fruit is cut in half and the inte- 438 GOURD TRIBE ; CALABASHES, PUMPKINS. rior is removed, furnishes two basins. Others grow in the shape of bottles ; and these sometimes attain the dimensions of six feet long by a foot and a half in circumference ; when very young and small, they are made into spoons. Such vessels are known in the East and West Indies, Arabia, Egypt, &c., as Calabashes. Some of the fruits from which they are made, are as harmless as the cultivated Melon and Cucumber; but others contain much of the bitter purgative principle ; and, in preparing the latter, it is requisite not merely to scoop out the entire pulp, but to allow water to stand in them, and to change this several times, till all the bitterness be removed from the rind. The common Pumpkin is remarkable for its rapid growth ; in good soil, and well supplied with water, it will form shoots 40 or 50 feet long, and will cover an eighth part of an acre ot ground in a season. Its pulp is eatable, but it is not much used in this country. On the Continent, however, it is frequently employed as an ingredient in various dishes ; and it is extensively culti- vated, for the purpose of feeding cattle and hogs, as well as on account of the seed, which yields an oil suitable both for food and for burning. The Vegetable Marrow, which within a few years has become a common dish, is the produce of an allied species of gourd. The Water Melon approaches in character to the Cucum- ber. Its fruit is so succulent that it almost melts in the mouth ; and in warm climates or in hot seasons, is a most refreshing article of diet. To the Egyptians it may be said to be both food and physic. It often grows to a large size even in this country ; but it is only between the tropics, that it attains its greatest dimensions ; in Senegal, one has been known to weigh 60 Ibs. 608. Very nearly allied to the Gourd tribe is the order PAS- SIFLORELE, or Passion- Flower tribe, which also consists of plants having creeping stems, supporting themselves by tendrils, and bearing large juicy fruit. This order is principally to be met with in America ; and its name is derived from the superstitious fancies, entertained by the Spaniards who discovered that con- tinent, respecting the flower, which they considered to be an allegorical representation of the crucifixion and sufferings of our Saviour. In its anthers, they saw his five wcunds ; in the three ORDER PASSIFLORE^E, OR PASSION-FLOWER TRIBE. 439 styles, the nails by which he was fixed to the cross ; in the column which rises from the bottom of the flower, the pillar to which he was bound ; and a number of little fleshy threads which spread from its cup, they compared to the crown of thorns. It seems difficult to imagine how such a notion could have been suggested to them; since the general aspect of the flower does not appear such as to be likely to excite it. Various species of Passion Flower are now naturalised in this country ; and are beautiful orna- ments to the fronts of houses, garden walls, or trellis-work, over which they may be trained. They sometimes climb to the tops of high trees, and hang down in elegant festoons from their branches. On examining the flower, we find that the calyx has five sepals, which are usually green on the outside, but are yellow, red, blue, or purple in their interior. The petals are equal in num- ber to the sepals, and are of the same colour with their inside ; sometimes, however, they are absent. Next within these, we do not at once come, as we might expect, to the stamens ; but we meet with several rings of beautiful fleshy threads, which spread from the calyx like rays, and are splendidly variegated with crimson or blue-and- white. These diminish in size towards the centre of the flower ; and at last. lose themselves, as it w r ere, in some little rings, that surround the base of the column, which now presents itself in the centre. These threads are to be re- garded either as stamens or petals in an undeveloped state ; it is FIG. 160. BRANCH of PASSION-FLOWEK. 440 PASSION-FLOWER TRIBE. of no consequence which we denominate them. In the centre of the flower, from the bot- torn of the calyx, rises a column ; at the top of which we ob- serve five an- thers. The column itself, of which the outside re- FIG. 161. A, SKCTION OF PASSION-FLOWER. B, CENTRAL COLUMN, sembles in CO- shmving the three styles at the top ; the five anthers, a, a ; the tube, ft, b, formed by the cohesion of the filaments ; c, the innermost lour the SUr- ring of the undeveloped petals ; d, the origin of the petals; e, the i- i origin of the ca yx. rounding DO- dies, consists of an exterior sheath, formed by the adhesion of the filaments to each other, and of an interior solid stalk, on the top of which the ovary is mounted. The ovary, when cut across, is found to consist of but one cavity ; the ovules, however, are attached to three parietal placentas (as in the Violet), showing that the seed- vessel is composed of three carpels; and the summit of the ovarium bears three short styles, which terminate in thick swollen stigmas. The fruit is a fleshy egg-shaped body, con- taining a number of pulpy seeds ; but it varies extremely in size and colour, in the different species. In all instances, kowever, it is destitute of any injurious principle, and may be eaten with safety. In the common Passion-flower, it is about as large as a hen's egg, and orange-yellow on its exterior ; in some tropical species, called Grenadillas, it is much larger, attaining the size of a man's head, and is greener in its colour. These are culti- vated on account of the slightly acid pulp they contain, which renders them refreshing ; and the rind, which is also a little acid, is cut into slices and made into tarts, which have somewhat the flavour of those made of apples. The substance which surrounds the seeds is not mere pulp, but is a sort of fleshy coat, termed the ORDER CRAS3ULACE.E, OR HOUSE-LEEK TRIBE. 441 arillus, which gradually rises from the bottom of the ovule, and at last envelops it completely. It will hereafter be seen that the spice known as mace, is the arillus of the nutmeg. A spe- cies of Passion-flower inhabiting the Isle of France is remarkable for the narcotic properties of its root ; but it is not unlikely that these are shared in some degree by others. 609. Passing over several small orders, we come to that of CRASSULACE^E, the House-leek tribe, which is chiefly interesting as containing several British species of succulent plants, which flourish under circumstances that would be fatal to almost all others. They are found in the driest situations, where not a blade of grass nor a particle of moss can grow, on naked rocks, old walls, sandy hot plains, alternately exposed to the heaviest dews of night, and to the fiercest rays of the noon-day sun. Soil is to them a means of keeping them stationary, rather than a source of nutriment. In this respect they resemble the Cacti and other plants of tropical climates, which they represent in more temperate regions. About half of the species known to Botanists are natives of the Cape of Good Hope ; and nearly half the remainder are European plants. Although they re- semble the Cacti, and some other orders, in the succulent nature of their stems and leaves, there is no other very close corre- spondence between them. The number of parts in the flower is subject to great variation. The calyx may consist of from three to twenty sepals, which are united at the base. The petals are equal in number to the sepals, and are inserted into the calyx ; they are sometimes distinct, and sometimes cohere into a mono- petalous corolla. The stamens are either equal in number to the petals, alternating with them ; or are twice as many, in which case those alternating with them are longer, and come to maturity earlier, than the others. The carpels are equal in number to the petals, and are opposite to them ; they are arranged in a circle, and are more or less adherent in different species, each having its own style and stigma. Every one contains several ovules, which are arranged in two series along its internal edge, where the dehiscence or opening usually takes place at the time of maturity. The Sedums or Stonecrops, of which many species 442 HOUSE-LEEK TRIBE ; ORDER CACTE.E. exist in Britain, belong to the Linnaean class and order DECAN- DRIA Pentagynia, having five parts in the calyx, corolla, and ovarium, with double the number of stamens ; whilst the Sem- pervwum, or House-leek, is found under DODECANDRIA Dode- cagynia, having twelve stamens and twelve styles. The common British species of the latter is remarkable, for almost always bearing ovules on its anthers, instead of pollen. These plants are not only very tenacious of life when naturally exposed to the elements, but resist efforts made to destroy their vitality, when it is desired to preserve them. The collector finds it very diffi- cult, therefore, to prepare them for his Herbarium ; for they wili push long shoots whilst under great pressure, and after being submitted to a high temperature. It is from the defi- ciency of stomata, and the thickness of the cuticle, that it is so difficult to dry them ; and it is obviously by these properties, that they are enabled to resist the rays of the sun. 610. The order CACTE^E, or Prickly Pear tribe, is by nature exclusively confined to the New World ; but several spe- cies have now been naturalised elsewhere. They do not, even on that continent, extend far from the tropics ; they fre- quent hot, dry, exposed situa- tions, like those to which the Crassulacese are adapted. Most of the species of this order are remarkable for the absence of leaves, of which no other traces are found, than tufts of prickles arising at regular intervals from the stem, .these being the veins of the leaves, be- tween which the parenchyma is not developed (. 236). The stems and branches are very fleshy and succulent, and usually have flat expanded surfaces, which in some degree per- Pre. 162. STEM, BRANCH, AND FLOWSR OF CACTUS. CACTUS, OR PRICKLY-PEAR TRIBE. 443 form the functions of leaves. In the various species of Cactus, however, we find the form of the stem differing greatly. Thus in one kind, known as the Melon-Cactus from its form, the stem is so much stunted as well as expanded, that it quite resemble? the fruit alluded to. In other species, however, the stems are round and greatly prolonged, resemblin^ ropes ; whilst in others, again, they are equally long, but are angular. All are adapted to the same circumstances of growth ; but the Melon-Cactus, from its greater bulk, in proportion to the surface it presents, can exist in the most exposed situations. It usually happens in tropical climates, that, during a certain portion of the year, a large quantity of rain falls, the atmosphere is loaded with damp- ness for many weeks, and the soil is completely saturated with water. During this time, the Cactuses live very fast, and dis- tend all the cavities of their tissue with fluid. The resistance afforded by their thick cuticle, and by the deficiency of stomata, to the evaporation of this, enables them to retain a store of it (as the Camel holds water in the stomach) until they can ac- quire a fresh supply. At other times, they may be said to live very slowly; the functions of exhalation, digestion, &c., are performed very inactively ; and the fluid which they have ab- sorbed during the rainy season is adequate for their support, during all those months when they cannot live upon the soil or the atmosphere. This property sometimes renders the Cactus tribe of great utility to man. On Mount Etna, for example, and itf, volcanic fields, it is the Indian "Fig which the Sicilians employ, to render such desolate regions susceptible of cultivation. This plant readily strikes into the fissures of the lava, and soon, by extending the ramifications of its roots into every crevice of the stone, and bursting the largest blocks asunder by their gradual increase, makes it capable of being worked. The juiciness of the stems causes them to be sought in the West Indies, during dry seasons, by the cattle; which, tearing off the thorny integu- ment that covers them, feed upon the moist pulp within. 611. The flowers of this tribe are commonly very showy ; and the number of handsome species, which have been of late introduced into our hothouses, gives them an air of splendour cc2 444 CACTUS TRIBE ; NIGHT-BLOWING CEREUS. unknown until recent years. No distinction can be traced be- c tween the calyx and corolla ; for the flow- ers branch off directly from the stem, and its cylindrical axis is covered with scale- like coloured bracts, which at the upper FIG. 1<>3. PARTS OF FLOWER OF CACTUS TUNA. A, , ., thickened axis, bearing the Stamens, a, the style, b, P^rt gradually pass and stigma, c ; and enclosing the ovariura, d. B, vertical j nto thm delicate D6- section of ovanum. C, transverse section of ditto. < \ talline leaves, which unfold, tier after tier, from within each other, adhering by their lower ends so as to produce a firm fleshy tube. From the inte- rior of this tube, spring a number of rows of slender stamens. The ovarium is situated in a cavity within the apparent stalk of the flower; and contains a considerable number of ovules, attached to parietal placentae. The style is a single column, springing from the top of the ovarium ; and, after rising above the anthers, it divides into a star-shaped set of stigmas, equal in number to the placentae. The beauty of the flowers is usually very short-lived ; some of them only last for a few hours. One of the most splendid species is the Cereus grandiflorus or night- blowing Cereus, the blossoms of which begin to expand about 6 or 7 o'clock in the evening, and are fully blown about midnight ; but, by 3 or 4 in the morning, they are quite decayed. During its short continuance, however, there is scarcely any flower of greater known beauty. The perianth, when open, measures nearly a foot in diameter ; the outer leaflets are of a dark brown colour, the inner ones are of a splendid yellow, gradually shaded, toward the centre of the flower, into a pure and brilliant white. When several of these magnificent flowers, therefore, are open at once upon a single plant, they seem like stars shining out in all their lustre, veri- fying the poet's declaration that Darkness shows us worlds of light We never see by day." CACTUS TRIBE ; COCHINEAL. GOOSEBERRY TRIBE. 445 Besides possessing beauty for the eye, these flowers are delight - fully fragrant, and fill the air with odours to a considerable dis- tance around. 612. When the flower has withered, the ovary enlarges and becomes pulpy, and is in time converted into a fruit which has much resemblance to that of a gooseberry, but is usually inferior in flavour. The juiciness of the fruit of many species, however, renders them acceptable in warm climates ; on Etna, for ex- ample, the large cooling fruits of the Indian Fig are sold in con- siderable quantity, and some of the varieties are of great excel- lence.* Independently of this use, the Cactus tribe cannot be said to be of any direct advantage to Man ; they indirectly serve him, however, in a very important manner. Several species of the order are infested with insects of the genus Coccus, some of which, especially the Coccus Cacti, become, from the colouring matter they collect from the fruit and flowers of the plant, of great commercial importance, being, in fact, the Cochineal of the painter and dyer. One particular species of Cactus contains a red juice more delicate than the others ; and it is when feeding on this, that the bodies of the Insects acquire the most brilliant tinge. Cochineal consists of nothing else than the dried bodies of the Insects, which are impregnated throughout with this colour. 613. The next order to be noticed is that of the GROSSU- LARLUB to this country. 448 SAXIFRAGE TRIBE; HYDRANGEA. celled. The styles are commonly distinct, but are sometimes adherent ; in the greater number of the tribe there are no more than two, indicating that the ovarium is made up of but two carpels. Each cell contains a large number of minute ovules. The fruit is ordinarily enclosed in the calyx, and opens only at the point. There is one genus, however, in which there is no adhesion between the calyx and ovarium ; and there are several in which the adhesion does not extend far up. In habit this tribe a good deal resembles some of the Rosacese. 616. The plants of this order are almost universally diffused over the globe ; but they cannot be said to be of any direct utility to Man. The name of the principal genus, Saxifrage, however, is probably derived from the power which may be attributed to the plants composing it, of breaking up the surface of the rocks on which they grow, by insinuating their roots into crevices, and afterwards causing them to distend in the same manner as the Cacteae have been just now stated to do (. 610). If this idea be correct, it is obvious that their function, in pre- paring the surface of barren rocks and mountain sides, for the habitation of plants of a higher order, is one of the most import- ant in the whole economy of nature. At least twenty species of this genus alone exist in Britain ; and some or other of them are found in almost every rocky or exposed situation. To this order belongs the very singular genus Parnassia (so named because it is said to abound on Mount Parnassus), the British species of which is the companion of the Sun-dew in its marshy haunts, and rivals it in singularity of structure. In the latter, the peculiar glandular hairs are found only on the leaves ; but in the Parnassia they exist on the flowers. Alternating with the stamens, there are five fleshy scales, divided at their edge into numerous rays, each of which is tipped with a beautiful pellucid greenish gland ; so that the flower, when viewed from above, appears set with sparkling jewels. The Hydrangeas, (which are not natives of Britain, but have been introduced from China and Japan,) are also marsh plants, and should be kept well supplied with water, when grown in gardens. A full- sized plant requires as much as from 10 to 12 gallons daily in HYDRANGEA. UMBELLIFEROUS TRIBE. 449 warm weather. When the floral envelopes are over-developed by cultivation, the flowers become barren, and the plant must be propagated by cuttings. They grow in closely-set clusters ; and a little examination of one of these will often disclose many curious irregularities, produced by the partial union of two or more flowers, arising from the want of room for their full deve- lopment. The regular number of the large coloured leaflets is four ; but not unfrequently we find a flower possessing five, six, seven, eight, or even more ; and the additional ones are easily shown to be derived from other flowers, which are partially fused or melted down, as it were, into the first. The Hydrangeas are likewise remarkable for the varieties of colour to which the same species, or even the same individual, is subject, according to the soil in which it grows. Their natural and most common colour is red ; in a poor soil, however, they become of a dingy green ; but when grown in richer mould, especially in peat- earth, and watered with an alkaline solution, or manured with wood-ashes, they assume a rich blue tint, and their clusters increase in size and present a very handsome appearance. 617. We next come to an order of great extent and import- ance ; and one that is marked by an evident peculiarity, which enables us to distinguish very readily, in almost every instance, the plants that belong to it. This is the order UMBELLIFERJE, the Umbelliferous tribe, so named from the peculiar arrangement of the flowers upon the stem, which pervades the whole group. If we look at a plant of any common species, such as the Parsley or Hemlock, we observe that the flower-stem divides at the top into a number of short slender rays, which all proceed from one point, just as do the stretchers of the umbrella. If the flowers were borne on these, the whole set would be considered as forming a simple umbel, such as we find in the Geranium and many other plants. But in the Umbellifera?, we commonly find that each stalk of the umbel subdivides again, bearing a second set of rays that carry the flowers at their extremities, which itself constitutes an umbel. The whole system is then termed a compound umbel; and it is this which is characteristic of the order. It may be further noticed, that the stems are 450 UMBELLIFEROUS TRIBE. almost always hollow, and that the leaves are usually much divided. 618. The separate flowers are generally very minute, and require good sight, or the aid of a magnifying-glass, for their parts to be distinguished. The calyx generally appears very small, seeming to consist only of a little narrow border, from within which the petals arise. This border is marked, however, by five indentations, showing that it consists of five adherent parts or sepals ; and these adhere not only to each other, but to the ovarium (which is consequently inferior), so that their points only are free, and these seem to spread out from the sum- mit of the seed-vessel. The petals are five in number, and spring from the top of the tube of the calyx ; between these arise five stamens. In the centre of the flower we observe two styles ; and these arise from the top of the ovary, which is two- celled, each cell containing a single pendulous ovule. These characters are so constant, that very nearly the whole of the order is contained in the Linnsean class and order PENTANDRIA Digynia ; the only exception being in a few species, in which the ovarium is made up of three carpels. As the fruit ripens, the seeds become adherent to the walls of the ovary ; and the two divisions of the latter separate from one another ; so that for the ripe fruit, we find two grains, which seem like seeds, and are commonly considered as such, although really consisting of the carpels enclosed in the tube of the calyx. They are fre- quently marked in a curious manner on the outside, by ribs or nerves which belong to the latter ; and it is in the substance of this envelope, that the little receptacles of secretion exist, which contain the essential oils that are characteristic of the grains of this order, such as those of Anise, Carraway, &c. 619. The strong general resemblance which exists between Umbelliferous Plants, makes it frequently a matter of some dif- ficulty to distinguish their various genera and species. This is the more to be regretted, as there is a great difference in their respective qualities, some being nearly or quite harmless, whilst others are virulent poisons. The Carrot, Parsnep, Celery, Fennel, Parsley, Carraway, Dill, Anise, Coriander, and Sam- UMBELLIFEROUS TRIBE. 451 phire, are all well-known kinds, which are useful for various purposes, the three former being very largely cultivated, as affording important articles f food ; whilst, on the other hand, the group contains the Hemlock, Cowbane, Dropwort, Fool's- Parsley, and many other species, which are more or less unwholesome. The fact is. that the general character of the order is to possess narcotic and acrid qualities, which are espe- cially abundant in some species, and which probably exist, in some degree or other, in all. In regard to the Carrot, and Parsnep, the same remark applies, which has been formerly made (. 659) respecting the Potato; that the edible portion consists principally of starchy matter deposited for the nutrition of the growing parts, and that this is consequently free, or nearly so, from the peculiar properties which characterise the order. The Celery, when growing in its usual manner, pos- sesses these properties in a degree which would render it injuri- ous as well as disagreeable to the taste ; and it is only by being blanched (. 288) that it is rendered palatable and wholesome. The Fennel and Parsley, of which the leaves are employed to flavour various articles of cookery, are by no means devoid of injurious properties, though the small quantities in which they are usually eaten do not cause them to be manifested ; the latter is said to be much more injurious to Parrots, than it is to Man or Cattle. These properties are generally contained in the leaves and stems alone ; and consequently the fruits of even the poisonous species are for the most part destitute of them, and may be used as aromatics. 620. Of the British species, the only one of which the juices are ordinarily used for medicinal purposes is the Conium macu- latum, or Hemlock, which derives its specific name from the spotted appearance of its stems, by which it is easily recognised. Although the order is more abundant in temperate climates than between the tropics, there are certain plants of warm climates which afford medicinal products of great value, known under the name of the foetid gums. They are of the nature of Gum- resins (. 378), and are distinguished by their powerfully dis- agreeable odour. Those most in use are Assafcetida and Galba- 452 ORDER LORANTHACE^, OR MISSELTOE TRIBE. num, which are procured from Persia and the East Indies, and are remedies of great utility in hysteric and spasmodic com- plaints. The geographical distribution of this order presents some points of much interest. Out of ahout 900 species, which it was estimated some time ago to contain, nearly three-quarters are inhabitants of the Northern Hemisphere ; and of these, by far the larger proportion belongs to the Old World. In the whole of America there are but about 160 species ; whilst in the extensive wastes of New Holland, and in the numerous islands of the Polynesian Archipelago, only about 70 are known. The number in Britain alone is not less than 66. 621. The order LORANTHACE.E or Misseltoe tribe may be next briefly noticed, chiefly on account of the curious habits of the numerous species it contains, which are nearly all parasitic upon other plants ; forming, like the Misseltoe, natural grafts with them, by insinuating their roots into their chinks, and de- riving from them the supply of sap afforded by the ascending current (. 320). The calyx of their flowers is adherent to the ovarium, and scarcely exhibits any trace of division into sepals ; its tube is enclosed at its base between two bracts. The corolla is formed of from 3, 4, or 8 petals, more or less united at the base. The stamens are equal in number to the petals, and are opposite to them ; their filaments are usually adherent to the petals ; but sometimes they are absent, so that the anthers are seated, as it were, upon the latter. The ovarium is one-celled, and contains but a single pendulous ovule ; there is only one stigma, and the style that should support this is sometimes ab- sent. The fruit is a berry, containing a viscid matter, like bird lime ; it is frequently eaten by birds, which drop the seed on the trees on which they perch ; and this, by the peculiar direction of its germination (. 321), insinuates its radicle into their stems or branches. 622. The principal genera of this order are the Vistum and the Loranthus. The former only inhabits Britain, and is known as the Misseltoe ; it is generally found parasitic upon trees of the order Rosaceae, such as the Hawthorn and the Apple ; and it rarely occurs on the Oak. Hence it probably was, that, when ORDER CAPRIFOLIACE^E, OR HONEYSUCKLE TRIBE. 453 growing on the latter tree, it was held in superstitious venera- tion by the Druids of old. The Loranthus, on the other hand, infests a great variety of trees, each of these having, for the most part, a particular species which grows on it alone. Above 250 species of it are known ; and these are mostly found in the tropical parts of America and India. In Africa, and in the South Seas, they appear to be very rare. 623. The next order, CAPRIFOLIACE.E, or Honeysuckle tribe, bears a nearer relationship to the foregoing, than might have been suspected. The flower chiefly differs from that of Loran- thacese in the stamens being alternate with the petals, instead of opposite to them ; and the ovarium frequently (but not always) contains more than one cell. The order differs, also, in the absence of parasitic habits. To this group belong not only the Honeysuckle but also the Elder, and, in the opinion of some Botanists, the Ivy ; as also the Guelder- Rose and Laurestinus, the latter of which is a beautiful garden shrub, bearing leaves and flowers all through the winter. All these plants are natives of the northern parts of Europe, Asia, and America ; they are less abundant as we approach the tropics, and are almost un- known in the southern hemisphere. The flowers and leaves of most of this order are strongly odoriferous ; the former are gene- rally very fragrant ; but the latter are frequently (as in the common Elder) foetid, and possessed of acrid properties. The bark is generally astringent ; that of some species has been used for tanning ; and that of others has been employed in medicine for the same purposes, and with similar effects, as Peruvian Bark. The berries of the Elder and of other species contain a good deal of sweet juice, which may be fermented into a kind of wine. Those of an American species, when dried and roasted, furnish the best of all substitutes for Coffee, which is afforded by a plant belonging to the succeeding order. Another species, known as the Snow-berry, is cultivated in gardens on account of the delicate white colour of its fruit. 624. The next order, RUBIACE^E, or Madder tribe, is a very extensive one, but is almost entirely confined to tropical countries. It comprehends the meanest weeds and the noblest flowering 454 ORDER RUBIACE^E, OR MADDER TRIBE. trees, obscure herbs with blossoms which it almost requires a microscope to detect, and bushes whose scarlet corollas are many inches long ; and includes a plant which affords one of the most grateful bever- ages that the luxury of Man has prepared, with others of nauseous and bitter taste, some of which in skilful hands, are most valuable medicines. The Rubiacese, excepting the section which contains the Madder and its allies, pos- sess stipules at the base of the leaves ; of which the last order are destitute. The calyx consists of a cup, enclosing the ovarium, and scarcely divided even at its edge. The petals of the corolla are adherent at their lower part into a tube ; their number is usually five, but varies from 3 to 8, as does also that of the sepals. The stamens are equal in number with the lobes of the corolla, and are alternate with them ; they are generally adhe- rent to the lower part of FIG. 167.-PART OF THE FLOWER OF COFFEE PLANT, the tube. The OVarium A, calyx inclosing ovary, with bifid style. B, tube usua lly contains tWO of the corolla cut open, showing the five divisions J ' <>f its upper part and the five stamens arising Sometimes many cells; the from it. . , . . i i . j style is single, but is di- vided at the top into a number of stigmas equal to that of the FIG. 1(56 COFFEE PLANT, showing the flowers and ierrics, and the stipules at the base of the leaves. ORDER RUBIACE-K COFFEE. 455 cells. The fruit is commonly a berry containing several seeds, inclosed in a fleshy covering ; or it may be a hard capsule merely ; or only one seed may have ripened, which is inclosed in a flesh, forming a drupe, like the Plum. The albumen of the seed is of a horny texture a peculiarity that is well exhibited in Coffee, which consists of the seeds divested of their envelopes. 625. Coffee might be obtained from several species of the genus Coffaea ; that derived from one, however, is so superior to the rest, that it alone is commonly cultivated ; and numerous varieties of it, depending in part upon soil and climate, are now known. The native country of the Coffee Plant is Arabia ; and the use of its seed as a nourishing and agreeable beverage, has been traced to a remote period, having been certainly common in Persia as far back as the year 875. Coffee was not intro- duced into Europe, however, before the year 1517; and it was a century and a half before it came into general use, even in the capitals, where Coffee-houses were established. The seeds were at first sold at an exorbitant price, as much as four or five guineas the pound. The plant was introduced into the West Indies by Louis XIV., from a specimen presented to him by the Dutch, in 1714, of which he sent offsets to Surinam, Cayenne, and Martinique ; and from this all the present plantations are descended. The East India plantations were derived from a similar common source, a plant in the Botanic garden at Amsterdam, which had been raised at Batavia, from seed pro- cured from Mocha, in 1 690. The Mocha berries are smaller, and possess a higher flavour, than those which are brought from the "West Indies. This is partly due to the difference of soil and temperature, and partly to a difference in the mode of culture. It would seem as if nearly the same quantity of the aromatic product were formed in each case ; but that, in the large seed it is diffused through a greater quantity of the tasteless albumen, and is therefore less intense. It has been confidently asserted that, if the West Indian Coffee be kept for several years, instead of being roasted and consumed as soon as it can be transported across the Atlantic, its flavour improves, and becomes equal to that of the best Mocha. 456 COFFEE TREE. 626. The Coffee-tree grows erect, with a single stem, to the height of about 8 or 10 feet, and has long undivided slender branches, not unlike those of the bay-tree. The blossoms are white, and are seated on short footstalks, altogether resembling the flowers of the Jasmine. The berry is red, resembling a cherry, and having a pale, insipid, and somewhat glutinous pulp, inclosing two hard nearly hemispherical seeds, of which the flat sides are opposed to each other ; the seeds are enveloped in a membrane, which resembles that forming the divisions of the core of the apple, and is called the parchment. The trees begin to produce berries when they are two years old ; and in their third year they are in their full bearing. The blossoms expand very rapidly, those of a whole plantation sometimes coming out in a single night, but they fade almost as rapidly. The pulp is separated from the berries, when these have ripened and have been gathered, in various ways. By some the berries are ex- posed to the sun, until they are perfectly dry, and the hardened pulp forms a husk, which is broken away with rollers. By others, the berries are exposed to the sun in layers, so that the pulp is caused to ferment. And by others, again, this is rubbed off in a sort of mill. The seeds, before being roasted, are nearly tasteless ; but during this process, a change seems to take place in the chemical arrangement of their particles, which produces the aromatic flavour and odour so highly valued. 627. When Coffee was first introduced into Turkey, the use of it was forbidden by the government, on the ground of its being an intoxicating beverage ; and the ministers of religion complained that the people forsook the mosques and crowded to the coffee-houses. It has since become, however, quite a neces- sary of life in Turkey ; so that at one time the refusal of a husband to supply his wife with a reasonable quantity of it, was reckoned amongst the legal causes for a divorce. The history of the present large demand for it in this country is very remark- able. In 1808, when the duty on coffee produced in British plantations was two shillings a pound, it was beyond the reach of the poorer classes of consumers. The total quantity con- sumed in Britain was then little more than one million pounds, ORDER RUBIACE^E PERUVIAN BARK. 457 from the importation of which the Government derived a revenue of about 160,000. But in 1824, the duty was lowered to six- pence a pound ; and the consumption has gradually increased to more than 28 million pounds, producing an import duty of 900,000. There are strong reasons of a moral nature for encouraging the consumption of Coffee, by cheapening its price to the lowest amount; for it has been satisfactorily shown that the more extended use of it has mainly contributed to promote improved habits amongst large classes of the community. 628. The order Rubiacese takes its name from the Rubia or Madder plant, which furnishes the most important of our crim- son dyes (. 392). It is only in tropical countries, however, that it presents its finest aspect ; but in some of these it is so predominant, that its species constitute about l-29th of the whole number of flowering plants. Amongst the most important of these are the Cinchonas, which furnish the Peruvian or Jesuits' Bark so largely used in medicine. This is very astringent, and might be used for tanning ; but its chief peculiarity consists in containing a large quantity of an alkaline substance termed quinine, which may be extracted from it by chemical means, and which, being the most valuable part of the drug, is now usually given in a pure state. This is almost a specific for agues ; and is extremely valuable as a tonic in weakened states of the system. The Cinchonas, of which the several species afford this product in varying degrees, grow in extensive forests in South America ; chiefly inhabiting the sides of the range of the Andes, between 10 North Lat., and 22 South Lat., and sometimes rising on these mountains to the height of 10,000 feet. It is from the trees growing in elevated situations, that the best bark is derived. Another most valuable remedy afforded by this order is Ipeca- cuanha, which is the powdered root of a little creeping-rooted, half-herbaceous plant, found in the damp shady forests of Brazil. This is chiefly employed in medicine as an emetic, and also to produce perspiration ; but it has several other important uses. 629. Passing over several orders of secondary importance, we come to one alike remarkable for its peculiarities of structure, for the large number of plants contained in it, and for the variety of 458 ORDER COMPOSITE COMPOSITE FLOWERS. size, colour, properties, &c., which these exhibit. The order alluded to is that of COMPOSITE or Composite plants, so named on account of the manner in which a number of flowers are clus- tered together so as to form one which is apparently single. We are in the habit of speaking of the Dais* , the Dandelion, the Sun-flower, the Dahlia, &c., as single flowers ; and yet every one of these is really composed of a head, on which a large num- ber of blossoms are crowded together. If any one of these be examined in its natural state (that is, not affected by cultiva- tion), it will be found to consist of the following parts. In the first place, the flower-stalk spreads out into a large fleshy ex- pansion, which is the disk or receptacle of all the florets united. Around the edge of this, we notice a whorl of small green leaflets; these are bracts, and .the whole circle is termed the involucrum. Above and within these, we notice one or more whorls of flat leafy-coloured organs, which at first sight appear to be single petals, but which will be presently shown to be so many distinct florets, of which the corolla has expanded itself on one side only. In the wild Daisy and Sunflower, only one whorl of these exists ; but in the cultivated Daisy, as in the Dahlia, they become numerous, from a cause that will imme- diately appear. Within these we find, crowded together upon the disk, a large number of minute flowers, scarcely having any perianth. That these are really such, can often be only distinctly seen with a magnifying glass. Every common Daisy of our meadows contains between two and three hundred such florets, each perfect in itself, that is having its corolla, stamens, pistil, and fruit. These central florets are termed florets of the disk ; in them the floral envelopes are but little developed, whilst the organs essential to reproduction are complete. On the other hand, the flat leaflets by which they are surrounded are called florets of the ray, from the radiating manner in which they are set on the receptacle ; in them, the corolla is developed at the expense of the reproductive organs, one or both sets of which are usually absent. If one of them be pulled up carefully at the end by which it was fastened to the flower, it will be seen that it Is not flat at the bottom, as it is at the top, but that it becomes STRUCTURE OF COMPOSITE FLOWERS. 459 tubular ; and that a little thread ending in two horns, issues from the tube ; this thread is the forked style, the stamens being here deficient. The coloured perianth in both these classes of flowers is evidently to be regarded in the light of a corolla ; where, then, is the calyx ? In the Daisy none is to be found ; but in the Dandelion and many other Composite plants, we may observe that, on rooting up each floret from the receptacle, a few little narrow hairy scales are attached to their lower end, form- ing a sort of down ; and this down or pappus is the only repre- sentative of the calyx. We shall presently see that, where it is present, it has an important function to fulfil. Below the pappus is the ovary, which is one-celled, and contains but a single ovule. The corolla of the florets of the disk is tubular from the bottom to the top ; at the top it widens, and is cleft into five little divisions, indicating that it consists of five ad- herent petals. The style terminates in two stigmas, which pro- ject beyond the mouth of a little hollow cylinder, that is found at the orifice of the flower. This cylinder, when examined with a magnifying glass, is found to consist of the anthers, which adhere together, side by side, so as to form a tube ; in other respects their structure does not differ from the usual character of these organs. The nature of this cluster of flowers may be better understood, by comparing it with an umbel, of which the radiating stalks have not been developed, so that the flowers which should be borne on them are all crowded together at the summit of the flower-stalk, from which these branches would have arisen. The fruit of each flower is a little grain, looking like a seed, but really consisting of a seed enclosed within the ovary. When the downy calyx exists, it remains attached to this, and forms a feathery plume, by which it is wafted through the air; and thus the seed is diffused and scattered by the wind. Every child who blows the delicate feathery balls of the Dande- lion, thus assists in the multiplication of the plant ; which it is very difficult to eradicate, when once it has gained a footing in a neglected garden, on account of this curious provision. 630. This order is one of very great extent, containing many thousand species ; and it is desirable to state its principal sub- H H 2 460 SUBDIVISIONS OP COMPOSITE TRIBE. divisions, as these may be recognised by examining the com- monest British species, as readily as may the characters of the order itself. Such florets as exist in the ray of the Daisy, Mari- gold, &c., are technically called ligulate or strap-shaped, from their flattened as- pect. Now in the Dandelion it will be found that both the ray and the disk are composed of ligulate flowers, to the en- tire exclusion of the tubular Ones ; Such FIG. 168. COMPOSITE FLOWERS ; A, CORYMBIFSIUE ; B, ClCHORACE.E. plants are ranked in a group named Cichoracece, from the common Cichory or Succory, with which they all agree in possessing a milky juice ; and this, when concentrated, is found to have narcotic properties. This group contains a large number of our wild flowers. From these will easily be distinguished the group of Cinaroce- phalce or Thistle-headed plants, which have, like the Thistle, a head of flowers, composed entirely of tubular florets, and of an almost hemispherical form ; these are further distin- guished, for the most part at least, by their hard and spiny leaves. To this section belongs the Artichoke, which is cultivated for the table, on account of the fleshiness of the scales or bracts, which form the involucrum ; -the fleshy bottom of these is the receptacle ; and the choke, which is thrown away, is a collection of florets, separated from each other by numerous stiff hairs. The third section includes those Composite plants, which contain both sorts of florets, ligulate ones in the ray, and tubuiar ones FIG. 169. COMPOSITE FLOWERS ; A, CORYMBIFKRJE ; B, ClNAROCKPHALJE. SUBDIVISIONS OP COMPOSITE TRIBE. 461 in the disk ; hence they are called Radiate flowers or CorymJA- ferce. It sometimes happens that no ray is present ; but the heads of tubular flowers cannot then be mistaken for those of the last section, since the florets of the latter are very wide-mouthed, and spread over the sides of the involucrum, the bracts of which are hard and spiny, whilst in the former case, the tubular flowers are narrow at the mouth, and are not longer than the scales of the involucrum, which are soft and leafy. To this Radiate group belong the Sun-flowers, Chamomiles, Daisies, Marigolds, Groundsel, Wormwood, the beautiful tribe of Asters which add so much to the splendour of our gardens, and thousands of other species. 631. It must not be supposed that the clustering together of the florets in heads is so essential a character of this order, that every plant in which it exists is to be regarded as belonging to the Compositaa. The contrary is the fact; for although no plants of this order have other than composite flowers, there are several in other orders, in which the flowers grow in heads. The most important single character is the adhesion of the anthers into a tube ; such perfect adhesion presenting itself nowhere else. Upon this is founded the Linnaean name of the group, which corresponds with the order Composite, the class SYNGENESIA. In the whole of the subdivision Cichoracece, all the florets are complete, possessing botli stamens and pistils ; this is also the case in the greater number of the Cinarocephalce ; and the plants having this character were arranged by Linnaeus into the order JEqualiS) from the equal character of all the florets. This order dso includes those of the CorymUferce which are destitute of ray. On the other hand, in the remainder of the Corymbiferae, the florets of the disk only are perfect, possessing both stamens and pistils ; and those of the ray seem to have the corolla developed at the expense of the stamens, which are absent : all the flowers, however, usually bear seed, those of the ray being fertilised by the pollen of those of the disk. This division was named by Linnaeus Superftua, from the florets of the ray being as it were superfluous. In the common Garden Marigold perfect seeds are produced in the ray only, and this belongs to the Linnsean order, 462 LINNJEAN SUBDIVISIONS; EFFECTS OF CULTIVATION. Necessaria. Lastly, there are a few of the Cynarocephalae in which the florets of the disk are perfect ; whilst those around the margin are larger than the rest, so as in some instances to form a sort of ray (being still tubular, however,) and are entirely infertile. These are termed by Linnaeus Frustranea, from their incomplete character. 632. It is chiefly among the Radiate group of this order, that those species exist, which are valued as garden plants ; and cultivation has frequently a remarkable effect on them. The corolla of the florets situated towards the margin of the disk undergoes an increased development, at the expense of the true reproductive organs ; and they are changed into ligulate florets, deficient in stamens, and exactly resembling those of the ray. This change is particularly evident in the Dahlia, which has repaid the attention it has received, by a greater improvement in the aspect of its flowers, than any other species, perhaps, has exhibited. In its natural condition, it possessed, like most of its group, but a single row of ligulate florets ; and all the centre of the flower was occupied by the ordinary yellow disk. Under the influence of a rich soil, however, the number of rows of ligu- late florets has gradually increased : and these have also under- gone great changes in regard to their size, elegance of form, and beauty and variety of colour. When a Dahlia is spoken of as eight, ten, or twelve-bloomed, it is meant that it has eight, ten, or twelve rows of ligulate florets. In its highest state of excel- lence as a garden flower, the florets of the disk nearly or alto- gether disappear ; and the smaller the eye (as it is termed) of the Dahlia, the better it is considered to be. Such flowers, however, are not fertile, that is, they do not produce ripe seed ; for the conversion of the complete florets into those bearing pistils only, occasions a great deficiency of pollen. It is curious to observe the change which will be produced in the flower of a Dahlia, if a root of the best kind be planted in a poor soil. There will be an effort, so to speak, to produce a large number of ligulate florets ; but these will be stunted and often curiously twisted ; so that the flower is even less handsome and regular than that of a much poorer kind. The Dahlia is a native of COMPOSITE TRIBE ; DAHLIA. ' , 463 Mexico ; and in its wild state it is a bushy herbaceous plant, growing to the height of about seven or eight feet, with flowers by no means remarkable for their beauty. It was introduced into this country soon after the commencement of the present century. 633. The foregoing general account of the structure of this remarkable order, is all that the limits of the present Treatise permit to be given ; a few remarks will now be added on its geographical distribution, its properties, and uses. The order attains its greatest development, in regard to the size of the species it contains, in the neighbourhood of the Equator ; for whilst, in the temperate parts of the world, Compositae are entirely herbaceous plants, those of Chili are bushes, and those of St. Helena are trees, almost the only ones native to the island. But in regard to number, it would seem that they predominate rather in temperate regions, especially of the northern hemisphere, where they are considered as forming about one-sixth of the whole vegetation. In Britain, about 140 species of them may be reckoned, constituting about one-tenth of the whole number of native flowering-plants. In France they are estimated at about one-seventh, and in Germany at one-eighth ; whilst in Lapland they are only one-fifteenth. In Sicily they are said to constitute more than half; and nearly the same proportion is found in some parts of North America. In the north of New Holland, on the other hand, the proportion is not more than one-sixteenth ; and of a collection of plants formed upon the western coast of Africa, it did not exceed one-twenty-third. The Cichoraceae have been ascertained to be more abundant in cold regions, and the Corymbiferae in hotter ones. 634. In considering the properties of the order /t will be necessary to advert separately to each of its subdivisions. The Cichoracece as already stated, possess a milky juice, which is bitter and astringent, as well as narcotic. These properties are strongly manifested in the Lactuca mrosa or strong-scented Lettuce ; for the juice, when concentrated, has narcotic effects sufficiently powerful to enable it to be used for the purpose of procuring sleep, instead of opium ; and the cells or vessels in 464 PROPERTIES OP COMPOSITE PLANTS. which it is contained, are so irritable at the time of flowering, that, if the surface be touched, the juice is forced out at the point. By proper cultivation, however, the injurious properties may be so far removed from several species of this group, such as the Lettuce, Endive, and Succory, that their fleshy stalks and leaves become wholesome articles of food. The roots, also, have often a considerable tendency to become fleshy, and may be generally eaten without danger. Those of the Succory are much used on the Continent, when roasted, as a substitute for Coffee ; and their powder is very commonly mixed with it, being considered by many persons to improve its flavour. The roots of the Scorzo- nera and Tragopogon are known under the name of Salsafy, and are cultivated for the table in some places to a great extent ; they are said to resemble those of Carrots and Parsnips in flavour. The roots of the Dandelion are used in Germany for the same purpose as those of the Succory ; but in this country they are more employed for medicinal purposes, the extract prepared from them being considered by many as a useful tonic, promoting also the various secretions. In common with many other plants of this tribe, its leaves and stems are believed to be an excellent food for cows, promoting the secretion of milk to a great degree. 635. In the Cinarocephalce, bitterness predominates ; and the principle to which it is due is generally mixed with gum, which is sometimes yielded by the plants of this group in great abun- dance. This bitterness is not found, however, in the unexpanded leaves, or in the receptacles of the flower-buds ; on which account they may in many cases be used as wholesome articles of food. This is the case with the Cardoon, the Artichoke, and several other species. The roots, also, of many species are edible. The flowers of several species yield a yellow dye, which is most powerful in the Carthamus tinctorius ; this plant is supplied from the Levant, and is often used to adulterate Saffron, as well as to tinge silk and cotton goods. 636. In the CorymbifercB, the bitterness common to all the Composites, is combined with a resinous principle of stimulating character, which exists, however, in very different proportions in the various species. Few supply articles of food ; almost the only PROPERTIES OP COMPOSITE PLANTS. CAMPANULACEJE. 465 species of which any part is eaten being a kind of Sun-flower, of which the root is known under the name of the Jerusalem Artichoke. The former part of the name is a corruption of the Italian Girasole, which means " turning towards the sun." The seeds of the common Sun-flower are a nutritious food for poultry, and they are made into cakes by the North American Indians; a large quantity of a fixed oil may be extracted from them (. 371). The roots of the Dahlia are fleshy, but their taste is very dis- agreeable. Of the medicinal properties of this group, those of the common Chamomile, which is in repute as a tonic and stomachic, are a good illustration ; but there are many species in which the bitter, the resinous, or the astringent properties are more predominant, and which have, therefore, their respectively peculiar uses. 637. Quitting this extensive and important order, we next proceed to one which appears very different, but which has, never- theless several points of affinity with it ; this is the order CAM- PANULACE^:, or Hairbell tribe, an extensive group, of which the species are scattered all over Europe, and in the cooler parts* of Asia and America, dwelling in dells and dingles, by the banks of rivers, in shady groves, and on the sides of mountains. The British species are humble plants, bedecked with no other orna- ment than a few blue or purple nodding flowers ; but in many foreign countries there are species of great brilliancy and rich- ness of appearance, which are more striking from the barren nature of the situations in which they usually grow. The genus Campanula is so named from the bell-\\ke form of its corolla ; to which the latter part of its common English name Hairbell also refers. Of this genus alone there are eight species in Britain, any one of which may be selected for examination. The calyx FIG. 170. DIAGRAM OF THE FLOWER OF CAMPA- NULACEJE. 466 ORDER CAMPANULACEJ3, OR HAIRBELL TRIBE. in this order consists of five adherent sepals, which enclose the ovarium, and then spread away from the top of it. The corolla has very much the figure of a bell, save that it is marked by five divisions at its edge, which show it to be made up of five petals ; and it is veined in a very beautiful manner. From its base, and consequently from the summit of the ovary, there spring five stamens, whose filaments are broad and leaf-like at the base, and curve inwards, so as to press the long narrow anthers against the style, around which they cluster in the unblown flower almost as do the adherent anthers of the Composite ; as soon as the flower unfolds, however, the anthers shrivel and fall back. The style is a taper stiff column longer than the stamens. It is covered all over, to the very tips of the stigma, with stiff hairs, which Nature has provided to sweep the pollen out of the cells of the anthers, as the style passes through them in lengthening. If it were not for this simple but effectual contrivance, the pollen, which is set free by the bursting of the anthers as soon as the flower opens, would drop out of the nodding flowers, and be lost, before the stigma is expanded and ready to receive the fertilising influence. The hairs of the style catch the pollen, and keep it, until, by the agency of insects, by wind, or by other accidents, it is brushed down upon the inverted stigmas. Many Cichora- ceae are also furnished with these collecting hairs, which thus constitute another point of alliance between the two groups ; this alliance seems the strongest in some species of Campanulaceae which have the flowers crowded together in heads. 638. On examining the ovarium of the Hairbell, we find that it contains three cells surrounding a central axis ; and that in each cell there is a large fleshy receptacle, to which a great number of minute ovules are attached. After these have been fertilised, and the rest of the flower has withered, the calyx still remains, inclosing the ovarium, and its sepals harden and enlarge ; stout ribs appear in the ovarium ; and the whole fruit, in ripen- ing, becomes dry, brown, and hard. In most of the order, the capsule opens in the usual manner ; but in the genus Campanula the mode is different. On looking at the top of the ovary between the sepals, the point at which the separation of the ORDER CAMPANULACE^, OR HAIRBELL TRIBE. 467 carpels generally commences, that part is found to be even tougher than the sides ; but Nature has provided another very simple means for the exit of the fruit, by the rending of the ova- rium (when every part of it becomes stretched so tight in drying, that some part of it must necessarily give way) at its sides, between the ribs, where the skin is weakest. The rent takes place in such a manner, as to leave a large orifice to each cell, through which the seeds are readily scattered. 639. A large proportion of the plants of the Hairbell tribe are as harmless as they are beautiful ; the roots of some species are eaten under the name of Rampion ; the leaves of others are used in Salads ; and the bells afford an abundant supply of honey to the Bee. The stem and roots abound in a milky juice (another character of alliance to the Cichoracese), which does not possess any deleterious properties. There is a subdivision of the group, however, of which a separate order has been formed by some Botanists under the name of Lobeliace^ the Lobelia tribe, which is distinguished for its extreme acridity. The species belonging to it are known by the irregular form of their corolla, which has some resemblance to the ligulate florets of the Composite ; and also by the partial cohesion of their anthers ; so that they approach the Compositse still more decidedly than do the true Campanulaceae. A character of much interest (which, however, can only be distinguished with the aid of the microscope) is, that in the true Campanulacece the pollen grains are round, whilst in the Lobeliacece they are oval. The plants of the latter group are most abundant in countries bordering on the tropics. Only two species are natives of England ; but many more have been intro- duced into our gardens, where they are valued on account of the beauty of their flowers. One species, the Lobelia inflata, a native of North America, has been used in medicine as an emetic and expectorant, and has been accounted a most important remedy for Asthma ; it is very uncertain, however, in its effects, and has produced fatal consequences when given in an overdose. 640. The last order of Calycifloral Exogens which will be here noticed, is that of ERICINEJE, the Heath tribe, a group of extreme beauty, which is easily recognised by certain peculiar!- 468 HEATH TRIBE. FIG. 171. DIAGRAM OF FLOWER OF ERICK^E. ties that distinguish it from all others. Of the common Heaths, the general aspect is known to every one ; but there are many species far surpassing these in size, and differing so much in appearance, that they would not be associated with them by an unpractised Botanist. The true Heaths are most abundant at tue Cape of Good Hope, where immense tracts are covered with them, and from which most of those exqui- sitely-beautiful spe- cies, which are che- rished in our gardens and green-houses, are derived. Their co- rolla might be likened to that of Campanu- lacese ; but the posi- tion of it is different; for both calyx and corolla are here beneath the ovarium, which is consequently superior. The calyxes usually small, and is cleft at the edge by four notches, which indicate that it is composed of that number of adherent sepals. The corolla is a tube, sometimes swelling out into a little globe, with four short teeth at the end, showing that this is composed of four petals, united up to their points. Arising from beneath the ovarium, and scarcely attached to the corolla, there are eight stamens, whose anthers are purple, and their two lobes separated towards their points like the prongs of a fork ; the anther-lobes, instead of bursting in the usual manner, open by pores or minute apertures at their extremities, a character which is peculiar to the Heath tribe, and marks every member of it. The ovary contains four cells, each including a great many ovules ; it bears a single style, having a flat purple stigma, with four little projections upon it. This in time changes to a dry capsule that bursts by valves, scattering an immense multitude of seeds almost as minute as grains of sand ; and these are frequently provided with little crests or fringes, which enable the wind to catch and disperse them, and are tech- nically called wings. ORDER ERICINEJE, OR HEATH TRIBE. 469 G41. The foregoing description applies especially to the true Heaths : there are many other species belonging to the order, which present several variations from it. For example, the calyx and corolla may be formed of five pieces, instead of four ; the number of stamens may be equal to that of the petals, instead of double ; and the number of cells in the ovary is vari- able. The essential characters of the order are the hypogynous stamens, and the opening of the anthers by pores. To this group belong the Rhododendrons, Kalmias, and Azaleas, which are now so abundant in our gardens ; giving them cheerfulness, by their evergreen aspect, even in the depths of winter ; and making them gay, with their beautiful blossoms, through the warmer parts of the year. The two former are natives of Ame- rica ; the latter comes from Asia Minor ; but they are now all naturalised in this country, though liable to injury from the cold of winter, unless they are planted in sheltered situations. The Rhododendrons and Azaleas differ from the rest of the group in the irregularity of the corolla, which has unequal divi- sions and spreads open at the mouth ; the stamens, too, are bent towards one side. The Kalmia is remarkable for the manner in which the stamens are held down by the corolla, until the pollen is ready to be shed ; the filaments are curved outwards, away from the pistil ; and the anthers are lodged as it were in little niches in the corolla, by which they are held, until the complete expansion of the flower, or any cause (such as the con- tact of insects) which gives the filaments a slight movement, sets them free, and they rise up with a spring, scattering the pollen on the stigma. 642. To what has already been stated of the geographical distribution of this order, it may be added that it is not abun- dant in Asia, and that it is almost unknown in Australia, where, however, its place is supplied by another, which differs from it in little but the structure of the anther. The general quality of the group is astringency; and several species have been used in medicine. Many species have succulent berries for fruit, which may be used as food ; this is the case with the Arbutus, sometimes called Strawberry tree, from the flavour 470 ORDER ERICINE^J, OR HEATH TRIBE. and appearance of its berry, from which an agreeable wine ia said to be prepared in Corsica. The Rhododendrons, Azaleas, and Kalmias, however, possess more active properties than the rest, and are decidedly poisonous to Man. The honey which ia made from their flowers has proved extremely deleterious to those who have eaten of it ; and it has been said that the flesh of Birds, that have fed on the buds of the Kalmia, becomes alike injurious. 643. The following tabular arrangement of the chief British orders that have been described in this sub-class, will assist the student in distinguishing them. SUB-CLASS II.-^-CALYCIFLOR^E. Sepals of calyx adherent into a cup or tube. Calyx united to the disk. Petals and stamens apparently springing from the calyx. A. Petals of corolla distinct, or nearly so. a, Carpels distinct, or but slightly adherent, each having its style and stigina. a, With stipules. Carpels numerous .... Rosacece, 593 Carpels solitary . . . . Leguminosce, 586 j8, Without stipules. Vegetation succulent . . . Crassulace is dis " FLOWERS ; B, single flower; C, three pistilline flowers, tinguished, is not that enlarged> the flowers are dif- ferent in themselves, but that they are crowded together upon or FIG. 176. BRANCH OF BREAD-FRUIT TUBE, bearing r, c, clusters of pistilline flowers ; b, clusters of stami- eous flowers. STRUCTURE OP FIG; BREAD-FRUIT. 497 within a receptacle. This will be readily understood, so far as the Bread-fruit is concerned, from the accompanying figures. The stamineous and pistilline flowers grow in separate clusters, which are of different forms ; that bearing the former is long, resembling a catkin; that of the latter is more globular, its bulk being principally composed of the fleshy receptacle on which the flowers are seated. The flowers are so much crowded together, that the perianth forms a cylindrical tube, composed of two pieces only. This, in the stamineous flowers, contains but a single stamen ; and, in the pistilline flowers, it envelops a one-celled and one-seeded ovarium. During the ripening of the fruit, the receptacle enlarges, and becomes still more fleshy and succulent ; and it is this which constitutes the edible portion. The structure of the Fig is extremely analogous to this; except that the flowers are borne on the inside of a hollow receptacle. This would not be understood upon examining the dry Fig only ; but, if the unripe Fig be cut open, its structure is at once perceived. Its firm fleshy exterior is the receptable, which has grown up around the flowers, so as to direct them inwards towards each other, as if they were growing on the inside of a basin ; this is not com- pletely closed over at the top, however ; for a little aperture is left there, which serves a very important purpose. The stami- neous and pistilline flowers are both included in the same recep- tacle ; but being so much crowded, the pollen of the former would not become applied to the stigmas of the latter, without some special contrivance. This is accomplished by the agency of insects, which enter the cavity through the hole at the top, and disperse the pollen by their movements. The seeds, which we meet with in the ripe Fig, are in reality little grains or nuts ; being the hardened ovaries, closely enveloping the true seed, like those of the Ranunculacese. 674. We have now briefly to notice the chief products of this order, which is surpassed by very few in its importance to Man. The Bread-fruit is the chief support of the natives of a large pro- portion of the islands that are scattered through the Southern Ocean ; it was introduced by the British Government into the West Indian Islands, where it grows very well ; but is not much 498 ORDER URTICE.E; FIG, BANYAN, HEMP, HOPS. relished by the negroes. The timber of this tree is liglit, and is used for building houses and boats ; and the inner bark is beaten into a kind of cloth. Nearly allied to the Bread-fruit is the Mulberry, which is well known to be the source of all our silken fabrics, as upon its leaves alone can Silk- Worms be profitably reared. The Paper-Mulberry affords the material of paper to the Chinese and Japanese, the inner bark being beaten into a pulp, and then pressed into sheets ; and its juice is so tenacious as to be useful as a glue. The Fig is an important article of food in many Eastern Countries ; and it is highly nutritious as well as agreeable. A very large quantity is exported from these to various parts of Europe ; as much as 1000 tons are annually brought to Great Britain alone, chiefly from Turkey and the Levant. Nearly allied to the Fig is the celebrated Banyan-tree of India (. 152) ; and also the famous Upas, which has been reputed to be the most poisonous species of the whole Vegetable kingdom, causing the death of animals which even approached it, or of birds which fly over it. It is quite true that its juice acts as an extremely violent poison, when inserted into a wound ; but the other effects attributed to the tree are not founded in fact. The Trumpet- wood of tropical climates affords the means of con- structing canoes, furniture, &c. ; and its fibrous parts are used as cordage ; the same portion of the Hemp -plant of northern regions, supplies the material, not only of our rope and twine, but of many of our coarser woven fabrics, such as sail-cloth. In India, hemp is cultivated for the sake of the properties of its leaves, which have an intoxicating power, resembling that of opium. This valu- able plant will grow in almost any climate and any soil ; the country in which it is most cultivated, however, is Russia, whence a large quantity is annually imported into Britain. The amount of hemp of foreign growth, employed in the country in 1839, was nearly one million hundred-weight. The fibres are separated and prepared very much in the manner of those of Flax. It is curious that the Hemp-plant destroys almost every other plant that grows in its neighbourhood ; so that it has been sometimes employed to clear from weeds a tract, which is afterwards to be used for some other kind of cultivation. The chief product of HOPS. ORDER PIPER ACE^, OR PEPPER TRIBE. 499 this order, that now remains to be noticed, is Hops ; this consists of the little scales, which form a sort of cone like that of the Fir, having a small pistilline flower at the base of each ; these scales are to be regarded as bracts. This plant, although apparently truly wild in many parts of the country, is considered by some to be not a native of Britain, having been introduced from Flan- ders about three centuries ago ; but it is now very extensively cultivated, as much as 56,000 acres being employed for hop- gardens, of which nearly all are situated in the counties of Kent, Sussex, Worcester, and Hereford. The duty upon their growth is heavy ; and the crop is an extremely uncertain one ; so that the price is frequently high, and is liable to great fluctuations. In 1837, the excise duty on the Hops grown in England amounted to nearly 311,000, of which the county of Kent contributed one half. Besides their use in brewing, hops may be made ser- viceable, through their narcotic properties, in procuring sleep ; the use of a pillow stuffed with them has been much recom- mended in cases of habitual wakefulness. 675. The small order PIPERACE^E, the Pepper tribe, claims notice on account of its utility to Man. Several hundred species are now known ; but they all so closely resemble each other, as to form no more than two genera. They are all tropical plants, abounding in the hottest regions ; and they all possess, in a greater or less degree, the pungent aromatic principle familiar to us. The Exogenous character of the group is by no means distinct ; and of it, with the addition of Menispermaeeae and a few other orders, Dr. Lindley has made a separate class, which he has termed Homogens. On the other hand, it has been placed by some Botanists among Endogens, more especially as in most species there is but a single cotyledon. The structure of the flowers is extremely simple. No vestige of the perianth remains, except a little scale, which is probably to be regarded as a bract; this protects the organs of fructification, which consist of a one-celled ovarium, surmounted by a stigma cleft into two or three divisions, and surrounded by two or three stamens partly adherent to it. These simple flowers are clus- 500 PEPPER . AMENTACEJE. tered together in spikes ; this is also the arrangement of the ripened grains, which consist of the ovarium inclosing the seed. These are known as black pepper ; and it is when deprived of their husk, that they constitute white pepper ; which is less pungent. The annual crop of each pepper-plant varies from half a pound to a pound ; and the whole quantity collected every year for human consumption, is probably not far short of fifty million pounds. Of this a much larger pro- portion is consumed in tropical countries, the in- habitants of which are fonder of highly-seasoned dishes than in Europe; nevertheless, nearly ten million pounds are an- nually imported into Bri- tain, of which only about FIG. 178.-BRANCH OF BLACK PEPPER, with spikes One-fourth is COHSUmed of unopened flowers above, and of fruit below; a, J n tne COU ntry. Pepper portion of flower-stem, with three flowers ; 6, single ' fruit ; c, the same cut open. from other Species forms a small proportion of the whole ; long pepper, as it is termed, is the unripe cluster of flowers, which has nearly similar properties with the fruit. Cayenne pepper, as it is termed, more properly Capsicum, is the seed-vessel of a plant of an entirely different natural order, that of Solaneae. 676. We now come to a very extensive group, which com- prehends a large proportion of the forest trees of our own country and other temperate regions, such as the Oak, Beech, Elm, CATKIN TRIBE ; POPLAR. 501 Plane, and Poplar, with the Birch, Willow, and many others. The name given to the order is AMENTACE^E*, or Catkin tribe, on account of the arrangement of the flowers in most of the species, forming what is termed a catkin t ; but this arrangement Fio. 179 BIRCH. is not universal. There is, indeed, considerable variety in this respect, as well as in the degree of completeness of the flowers, which sometimes contain both sets of organs, whilst in general the stamineous and pistilline flowers are distinct, sometimes, even, being on separate trees. They all agree, however, in the simple structure of the flowers, as well as in other particulars. * Professor Lindley divides the Amentacese into several orders. f A catkin is a long flower-stalk on which the flowers are closely set ; and differs from a spike only in this, that the whole falls off together, as is seen in the Poplar or Willow. 502 CATKIN TRIBE; POPLAR, HAZEL. FIG. 180. CATKINS OF BIKCH. When the stamineous flowers are distinct, they are generally destitute of perianth, but the stamens spring from a sort of scaly disk ; they are usually clustered to- gether, either on a long stalk, forming a catkin, or on a sort of head. The pistilline flowers com- monly possess a perianth in one whorl ; they are sometimes solitary, and sometimes arranged on a catkin. "What may be regarded as the most cha- racteristic structure of the group, is seen in thePojt?- lar and Willow. In these, the stamineous flowers are on one plant, and the pistilline on another ; and both are arranged in catkins. Each of the former consists of a little bract, protecting one or many stamens ; and each of the latter consists of a nearly similar bract, on which is set a one-celled ovarium containing many ovules. The fruit opens by two valves, which discharge a multitude of small seeds, covered with fine hair or wool, like the seeds of the Cotton plant. The Willow has no trace of a real calyx ; but the Poplar has a sort of membranous cup, which may be considered as the rudi- ment of one. 677. A nearly similar structure is seen in the common Hazel; in which, however, the two kinds of flowers are arranged on the same tree ; and the fruit more resembles that of the Oak. The stamineous flowers grow in catkins ; but the pistilline flowers grow near these, clustered together within a scaly envelope, which looks like a little bud. At the time when the stamens are shed- ding their pollen, the clusters will be recognised by the little red threads protruding from their points, which are the stigmas. CATKIN TRIBE; OAK, CORK. 503 The ovarium will be found carefully inclosed in the scales of which the bud consists, and protected by a quantity of soft hair. The ovarium contains two cells, with an ovule in each ; but only one of these usually comes to perfection. The fertilisation of the seed is insured by the immense quantity of the pollen dis- charged from the numerous anthers, which settles upon every- thing around as a fine dust. Each pistil has a sort of imperfect calyx arising above the ovary, the remains of which may be traced at the point of the nut ; but it is also inclosed in an involucrum of bracts, which increases as the fruit ripens, and almost envelops it, forming the husk of the nut. When the spring is mild, all the ovaria are fertilised, and the nuts ripen in clusters ; but in cold springs it often happens that some of the pistilline flowers are destroyed, so that only single nuts are found in the place of the clusters. In the Oak and Beech the calyx is much more definite ; and the involu- crum is very peculiar in its structure, hard- ening into the well-known cup of the Acorn, Beech-mast, &c. The cells and ovules contain- ed in the ovary are frequently numerous ; but only one seed usually comes to perfection. 678. The importance of this order, on account of the valuable timber which it yields, is so well known, that it need not be here dwelt upon. It may be well to mention, however, that in pro- pagating the various species, great care should be taken to select those whose wood is most durable. There is a remarkable differ- ence in this respect, between two species of Oak, which are commonly grown in this country. Of one, which has the acorn- Fro. 181. ACORN. 504 CORK-TREE. ORDER CONIFERS. stalks long, and the leaves short, the timber is cloee-grained, solid, and not liable to rot ; whilst the other, which has the acorn-stalks short, and the leaves long, affords a wood of much looser texture, very apt to decay. The former is the Old English Oak, of which those ancient fabrics are constructed, that have resisted the ravages of time for many hundred years. The latter was probably introduced from the Continent about three hundred years since ; and being more easily propagated, and of quicker growth than the other, it has been latterly substituted for it, especially in the New Forest, in the Northern counties, and in the neighbourhood of London. It is not unlikely that the late prevalence of dry-rot in our dock-yards is partly due to this cause. 679. Next to timber, the most important product of this order is Cork, which is a portion of the bark of a species of Oak common in the South of Europe. This peculiar substance, which consists entirely of cellular tissue, exists in many trees ; but it is most abundantly found, and most quickly renewed, in this one. The cork is first taken off when the tree is about fifteen years old, and the next crop is removed ten years after ; these two, however, are of little value, being thin and full of fissures. Afterwards the operation is repeated every eight or ten years ; and a tree thus barked will live a hundred and fifty years. The importance of the secretions of tannin and gallic acid, which are afforded by the bark, acorn-cups, and gall-nuts of this order, has been formerly dwelt on (. 365 and 399). Willow bark contains a bitter principle, which has been used in medicine as a substitute for that obtained from the Peruvian Bark. The Myrica cerifera, or Wax-plant of North America (. 381), is a species of this order, allied to the Gale or Dutch Myrtle of this country. 680. The last order to be noticed in this group, differs so remarkably from all the rest, and in fact from all other Exogens, that some Botanists consider it in the light of a separate class. This is the order CONIFERS, all the members of which are dis- tinguished by their fructification ; this having the form of cones, of which those of the common Fir, Larch, &c., are examples. CORK-TREE. ORDER CONIFERJ2. 505 These cones consist of a number of thick hard scales, which are adherent together until the organs of fructification are nearly mature, when they separate, so that the structure of 'the parts within can be distinguished. At the bottom of each of these scales are two ovules, which are not enclosed in anything like a seed-vessel. Hence these are the only true naked-seeded or gymnospermous Exogens ; and the peculiarity is a very striking one. The dense scales were formerly oonsid-ered as bracts ; but FIG. 182 INFLORESCENCE OF ABIES EXCELSA. a. Male Catkin. 6. Anther, sheddira; its pollen, c. Female catkin, d. Scales of female catkin, e. Scale of ripe cone. /. Seeds. little bracts may be often found at their base ; and they are now regarded as the carpellary leaves, which have not folded in to enclose the ovules (. 462). The stamineous flowers are arranged in catkins, much resembling those of the last order. The pollen grains fall directly upon the open points of the ovules ; so that 506 ORDER CONIFERS; NATURE OF COAL. the process of fertilisation is here as direct as it possibly can be. The seed is remarkable for having, in many species, a sort of verticil of cotyledons instead of two only ; but these arise in the same manner as the two which we find in other Dicotyledonous plants, and may be regarded in the same light as leaves which present a corresponding sub-division (. 235). 681. The Coniferse certainly present the nearest approach to Cryptogamia, which we anywhere find in the class of Exogens. Their organs of fructification are reduced to the simplest form they can possess, whilst still maintaining the character which distinguishes the reproductive process in Flowering-plants. (. 432). In the mode of growth of their stems, they are clearly Exogenous ; differing from other trees of that class in little, ex- cept that they do not possess ducts, and that their woody fibre is of large diameter, and possesses glandular dots (. 78). It is extremely interesting to be able to prove, by examination of such minute points of structure, the real nature of those vast deposites of Coal, which have long been a source of perplexity to those who interest themselves in inquiries into the history of our globe. Although in most instances the structure of Coal has been so much altered, by the combined agency of water, heat, and pres- sure, that it cannot be clearly distinguished, pieces may not un- frequently be found, in which it is very evident, when examined with the Microscope. It is then seen to correspond with Coni- ferous wood, both in the characters which have been just men- tioned, and also in the presence of a number of little receptacles for secretion, in which a fluid is contained. This fluid may be separated by distillation at a temperature beneath that of boiling water ; and it is found to be identical with Oil of Turpentine. It has been supposed, from the abundance of these remains of Pine forests, and from the absence, in the same deposites, of the remains of wood belonging to higher tribes of Plants, whilst the stems and leaves of Tree-ferns have been most perfectly pre- served, that none of those higher tribes existed on the Earth's surface at that period. This inference, however, must not be relied on ; for it has been found, by placing pieces of various kinds of wood, with Fern-leaves, and other Cryptogamic struc- ORDER CONIFERS; VAST AMOUNT OF DEAL TIMBER. 507 tures, to decay together in water, that, whilst all traces of Oak, Elm, Beech, and other hard woods were lost, the Coniferous woods could be distinguished, as could also the Palms ; whilst the Ferns underwent little alteration. If such a process took place, as is probable, at a former period, the remains would be just what we find them ; although many of the more perfect Exogens might have contributed to form them. 682. The various species of this order are distributed, as is well known, over the whole globe ; but they principally abound in temperate latitudes, and flourish on the sides of lofty hills, where no other trees will grow. They are of great service in rendering ground fertile for other kind of vegetation, by the decay of their leaves and resinous excretions, at the same time that they are themselves a source of profit. Some species grow to an enormous height, as much as 230 feet, with a perfectly straight stem. Every one is acquainted with the value of deal timber, on account of its combination of softness with elasticity and firm- ness, the size at which it may be readily obtained, the ease with which it may be worked. The greatest part of that which is used in this country, is brought eitner from Canada, or from Sweden, Norway, and Russia ; the latter, which is called Baltic timber, is of the best quality, but is partly kept out by a heavier duty. The total quantity imported, is probably a great deal more than a million loads per annum, by far the most bulky product which is brought to this country ; the amount contri- buted to the revenue by the duty paid on it, is about a million and a half sterling annually. 683. The general characters of the foregoing orders are so distinct, that they will not be made more evident by being ar- ranged in a table. L r, 2 508 CLASS II. ENDOGENS. 684. The number of orders belonging to this division of the Phanerogamia is much less than that of the Exogenous class ; and many of these are of little importance to Man. There is one, however, which surpasses all others in the benefits, direct and indirect, which the human race derives from it. This is not, as might be imagined, an order consisting of lofty trees, whose stems and branches afford valuable timber, whose fruits serve as whole- some and nutritious food, and whose juices possess properties that render them valuable as medicines ; but a tribe containing few save humble and apparently insignificant plants, undistinguished either by the beauty of their flowers, the fragrance of their odours, or the delicacy of their leaves ; and having nothing in their general aspect, which could afford the slightest indication of their value. This order is that of the Grasses, which affords to Man his entire supply of the most nutritious of all vegetable substances, and on which are almost entirely supported the domestic animals which he rears for the food they yield, and for the other valuable products derived from them. We shall here- after find, that this order ranks very low in the scale, considered in regard to its structure alone ; and it is interesting to observe, in this as in so many other instances, the apparently insignificant means which the All- Wise Creator employs to effect objects of the greatest magnitude. It will be remembered that, in the class of ENDOGENS, the parts of the flower are generally arranged in threes, not in fours or fives. 685. The first order to be noticed is a small one, containing the British aquatic plants named Frog-bit (Hydrocharis) and Water Soldier (Stratiotes), as well as many foreign species, espe- cially in North America where it is most common ; the first- named of these plants may be regarded as the type of the group, it is named after it HYDROCHARIDE^. The Frog-lit, (some- times formerly called the lesser Water-lily, from its supposed resemblance to the plants of the order Nymphacese,) is common ORDER HYDROCHARIDEJE, OR FROG-BIT TRIBE. 50 tf in many ditches and ponds in this country ; it has long stems which float on the water, sending down roots at intervals below, and erecting its leaves and flower-stems a little above the sur- face. The veins of the leaves run nearly parallel from the foot- stalk to the apex, and are united by little cross bars. The staminiferous and pistilliferous flowers are here distinct; the former are sometimes called barren flowers in botanical works, because they do not bear seeds, whilst the latter are spoken of as infertile flowers. This is an incorrect application of terms, since the pistilliferous flowers can no more produce seed without the pollen of the staminiferous, than the latter can without the ovules of the former. In both kinds of flowers, we find a calyx of three sepals, surrounding a corolla with three petals. In the Frog-bit there are nine stamens, disposed in three rows, on the one flower ; and within these, three imperfect styles ; but in other species, the number of stamens is indefinite. The other flower is destitute of stamens, and has an inferior ovarium, consisting of six adherent carpels, with separate styles and stigmas, each carpel containing numerous ovules. In some the order, the partitions dividing the seed-vessel give way, so that the ovarium contains but a single cell. 686. The Stratiotes, which has been so named from its sword- shaped leaves and its fancied military appearance, is a very orna- mental aquatic. It remains submerged during the greater part of the year, but raises itself to the surface on special stalks during the flowering season, by means of which contrivance the pollen may be scattered upon the stigmata. A still more curious means of effecting this object is met with, however, in another plant of the order, the Vallisneria. This plant, unlike the two already named, which prefer still waters, grows in rivers and rapid streams, of which the level is undergoing frequent and consider- able variations. Now it is essential to the well-being of the plant, both in regard to the fertilisation of the seed and the ripening of the ovule, that the pistilline flowers, from the time of their expansion, should be kept on the surface of the water, and secured from frequent submersion. This is effected by a 510 VALLISNERIA ORDER ALISMACEJE. very curious contrivance. They are themselves so constructed as to be lighter than water, and they are mounted on long cork- screw-like stalks, which are endowed with elasticity enough to enable them to extend when the surface of the water rises, just like a spiral spring when it is stretched out ; whilst these con- tract again as the water sinks, so as still to keep the flower in close apposition with the plant. But the staminiferous flowers have no such provision ; and as these grow from the part of the plant which is continually submerged, it would not seem evident how they are to come into proximity with the others, more especially as they commonly grow from separate roots. It has been observed, however, that, when the pollen is mature, and the anthers are ready to burst, the flowers producing it detach themselves ; and, rising by their lightness to the surface of the water, they mingle with those already floating there, and dis- charge upon them their pollen, as soon as their petals are ex- panded under the influence of the sun. It has been further observed that, when the seeds are ripened, the spiral peduncle again contracts ; and, carrying down the capsule, buries it in the mud. 687. The plants of this order are found in the ponds and streams of most countries ; scarcely any of them, however, have been applied to any useful purpose ; and none are characterised by any remarkable properties. 688. Another small order of aquatic Endogens is the one to which the Sagittaria (. 227) belongs ; it also includes a still more common plant, the Alisma Plantago, or Water Plantain, from which the name of the order, ALISMACE^J, is derived. These are alike in most , i , Fro. 183. FLOWER OP ALISMA respects, in the Structure 01 the PLANTAGO, with the corolla removed, parts of fructification : but the 8bowin s three se pais of calyx, and six stamens; a, undeveloped stamen. former has the pistillme and stami- niferous flowers distinct (hence belonging to the Linnsean class FLOWER OP ALISMA, OR WATER PLANTAIN. 511 Mono3cia), whilst the latter has the two sets of organs united in each flower (and hence belongs to the Linnaean class Hexandria) : the former also has more stamens than the latter. The Water Plantain has oblong, heart-shaped, pointed leaves, marked with about seven nearly parallel ribs or principal veins : and these are united by cross-bars, so that a kind of network is formed. The calyx consists of three distinct green sepals ; and the corolla of three delicate pink or white petals. There are six stamens in this species of Alisma, two placed opposite each sepal ; so that there must evidently be some portion of the flower deficient; since neither of these stamens corresponds with the centre of the sepal, as it should truly do, but each with one of its edges. Upon a more minute examination, a little glandular body may be found at the base of each sepal, and between each pair of stamens ; this is obviously a rudimentary stamen, and thus the whole form an undeveloped whorl, perfectly opposite to the sepals. But neither of the six stamens stand opposite the petals, as one whorl should do if the flower were regular; so that we must imagine the rudiments of another row to exist in a state of still more complete want of development. In reality, then, the flower of Alisma, although containing six stamens, or two whorls only, must be regarded as constructed upon the plan of twelve stamens in four whorls, of which the outer can only be traced in a rudimentary state, the second being entirely deficient, and the two inner ones only being apparent. This scheme of suppression of parts may be expressed thus : I Sep. Sep. Sep. 2 Pet. Pet. Pet. 3 8 s 8 4 o 5 8t Bt Bt 6 Bt st Bt The first line represents the position of the sepals ; the second that of the petals alternating with them; the third that of the, rudimentary stamens opposite the centre of the sepals ; the fourth 512 ORDER ALISMACE2E, OR WATER-PLANTAIN TRIBE. that of the deficient stamens, which should be opposite to the petals ; and the fifth and sixth, the rows actually present, the position of which does not properly correspond with that of the outer whorls of the flower.* Now this view of the matter, which may be considered forced and speculative, is very interesting when it is compared with the fact, that the tendency to the pro- duction of one or two additional whorls of stamens, which have been inferred to exist in this instance, is actually manifested in other species of Alisma, one of which has nine, and another twelve stamens. Had the six stamens been in the position represented in the third and fourth lines, there would have been no reason to suppose that any more existed in an undeveloped state, or that the plant was likely to be allied to any with 9 or 12 of these organs. The ovaries of the Alisma Plantago consist of about twenty-four (eight times three) carpels, which are quite distinct from each other, every one having its own style and stigma ; they are arranged in a somewhat triangular manner, in three clusters. The number varies in other species, and may be regarded as indefinite. In most instances, there is but one ovule in each cell ; and the fruit consists of a triangular head of dry one-seeded nuts, very much resembling that of the Ranunculacese. From the aquatic species of that order, indeed, in which the veining of the leaves departs from the regular Exogenous cha- racter, and the parts of the flower are arranged in threes, this group is not far distant ; and this is one of the instances which show that even the most positively defined groups are liable to approach one another, through aberrant forms, in which the characteristic peculiarities of each are shaded off, until they almost blend together. 689. Some Botanists separate from this order the Butomus or Flowering-Rush, and its allies, on account of their many- seeded follicles, to the whole inner surface of which the seeds are attached; this plant receives its scientific name (which * This view is given on the authority of Dr. Lindley ; if the idea formerly suggested (. 303), however, should prove well-founded, as to the parts of a verticil being often formed by a single leaf, a much simpler explanation of the double row of stamens may be adopted. ORDER LEMNACE.E, OR DUCKWEED TRIBE. 513 means cut-mouth) from the injury done by the sharp leaves to the mouths of the cattle that browse upon them. There is a marked difference in the properties of the two groups ; for the British species of Butomus is one of the most acrid of our plants, its leaves being sometimes used as a purgative; whilst the Alismaceae are much less so, their rhizoma or horizontal stem, which is fleshy in some species, being eaten as food by the Tartars and Chinese. 690. The next two orders, both consisting of aquatic plants, may be considered as presenting a near approach to the aquatic Crypto- gamia in general structure ; and some species are very like Algje in external aspect. They are FIG. 184BuroMUS. f J , clearly separated from them, how- ever, by their organs of fructification ; but these seem reduced to almost their simplest possible form. In the common Duck- weed, for example, of which almost every pond will supply us with specimens, the whole plant consists of a little green scale, looking like a leaf, but really a compound of stem and leaf, from the under side of which, as it floats on the water, hangs down a single root-fibre. Few persons are aware that the Duckweed ever flowers ; indeed there are some kinds which appear to reproduce themselves only by buds, as no organs of fructification can be detected ; but, if properly sought for, the flowers of this little plant may usually be seen in the months of June or July. If the eyes be attentively fixed on a mass of it, on a still sunshiny day, a few minute straw-coloured specks may very probably be discovered here and there upon the edges of the plants ; they have a sparkling appearance, which attracts observation. These are the anthers ; and if the plants possess- ing them be more carefully examined, especially under a micro- 514 ORDER NAIADE^E. GRASS-WRACK, POND-WEED. scope, the whole flower will come into view, having been pre- viously hidden in a slit in the edge of the scale. The inflo- rescence consists of a transparent membranous bag, having a split on one side, through which the two stamens of the stamineous flower pass out ; and within is also a pistilline flower with a single-celled ovary, having a single style and stigma. The sheath that incloses these is probably to be regarded as a large bract or spathe, like that which will be particularly described in the Arum tribe. Such are the means by which this little plant propagates itself, which it sometimes does with amazing rapidity. The Duckweed is so named, from its being a favourite article of food with water- fowl. It is the only genus PIO. 185.-A, SCALE OK DUCKWEED, with of its kind known in Europe ; flower a at its edge. B, THE FLOWER BEPA- and from itg sc i en tific name, Lemna, the group of which it may be considered as the type, is called LEMNACE.E. In tro- pical countries, the surface of the water in ponds, tanks, &c., is often covered with a sort of gigantic Duckweed, termed Pistia ; this has acrid properties, with which it is said to impregnate the water to such a degree, as to make it unwholesome. Neither Lemna nor Pistia have spiral vessels ; so that in this respect they might be associated with Cryptogamia. 691. In the order NAIADES, we have almost as near an approach towards flowerless plants; they are believed to be equally destitute of true spiral vessels ; and they possess no dis- tinct cuticle. In their general form and habits, many of them strikingly resemble AlgEe ; from which, however, they are at once distinguished when in flower. Of the British species, this resemblance is the strongest in the Zostera marina, or Grass- wrack, which is abundant on many parts of our coasts, and in ORDER NAIADE/E. GRASS- WRACK, POND-WEED. 515 the creeks and salt-water lakes that pass inland. It is used, where it is common, for packing glass bottles and earthenware ; and also in cottages for making beds and cushions. The Pond- weed (Potamogeton) of which a large number of species exist in Britain, is another plant of this order ; its roots are fed on by swans, which devour them with avidity, whilst its seeds are a favourite article with ducks. One species is said to grow in the Swiss lakes to the length of from ten to twenty fathoms, forming as it were extensive subaquatic forests, in those vast natural reservoirs; in Siberia the roots of the species which most abounds there, are used as food by Man. The flowers of the plants of this order have a calyx and corolla, each consisting of two little scales, which very early fall off, and occasionally are altogether absent. Some species are monoecious, whilst others possess complete flowers. The stamens and carpels exist in a small definite number; but this varies in the different species. In Potamogeton there are in each flower four anthers, which, not being elevated upon filaments, are said to be sessile ; and four ununited carpels, which become four small nuts. On the other hand, Zostera is monoecious. The plants of this order are most abundant in countries beyond the tropics, although they are also found near the equator. Potamogetons exist in almost every ditch and swamp, as far north as Iceland. Order ORCHIDE^, or Orchis Tribe. 692. The plants associated with the common Orchis in this order, exhibit some of the most curiously-interesting modifica- tions of structure, that any group in the vegetable world affords. Most of them are remarkable for the resemblance between their oddly-shaped flowers, and various objects with which they may be compared; thus two species of this country are known as the Bee-Orchis and the Fly-Orchis, from the similitude between their flowers and those insects ; whilst others are known as the ORDER ORCHIDE^E, OR ORCHIS TRIBE. Man-Orchis, the Lizard- Orchis, and the Lady's Slipper. Ic some foreign species there is an equally strong resemblance to large and splendid Butterflies and other Insects ; one, again, reminds the observer of a grinning monkey ; whilst another resembles an opera- dancer suspended by the head. The accompanying figure represents the Spider- Orchis, in which the likeness to the body of that animal is very striking. The Orchideee of Europe grow on the ground, in meadows, marshes, or woods ; and they are justly considered as among the most curious and beautiful plants of its Flora. But it is in tropical countries, in damp woods, or on the sides of hills, in a serene and equal climate, that they are seen in all their beauty. " Seated on the branches of living trees, or resting among the decayed bark of FIG. ^-SPIDER ORCHIS. f a u en trunks, or running over mossy rocks, or hanging above the head of the admiring traveller, sus- pended from the gigantic arm of some monarch of the forest, they develop flowers of the gayest colours, and the most varied forms, and often fill the woods at night with their mild and delicate fragrance. For a long time such plants were thought incapable of being made to submit to the care of the gardener ; and Europeans remained almost ignorant of the most curious tribe in the whole vegetable kingdom. But it has been dis- covered of late years that, by care and perpverance, they may be brought to as much perfection in a hot-house as they acquire in their native woods ; and they now form the pride of the best collections in England." It is chiefly in the almost impenetrable ORDER ORCHIDEjE, OR ORCHIS TRIBE. 517 forests of South America that the epiphytic species (those that grow upon the surface of trees) are found ; but in the hot damp Fio. 187- AKRIDES ARACHNOIDBS. parts of the East Indies, other kinds are very abundant. Some epiphytic species are known as air-plants, from their power of vegetating when simply suspended in the air, without any soil or any direct supply of water, supported only by the moisture of the atmosphere ; so that, when hung up by strings from the ceiling of a room, they will live for weeks and even months, and will go on blossoming luxuriantly. Hence they are some of the most favourite ornaments of the houses in China and Japan, of which countries they are natives. 693. As the structure of the flower is that which is most peculiar in this group, we shall proceed at once to a description of it. The short peduncle on which the flower seems to be borne, is in reality its ovarium, the position of which is inferior 518 STRUCTURE OF FLOWER OF ORCHIDE^E. in this order, whilst its form is slender. This contains but one cell, having three parietal placentas, from each of which arise a great num- ber of ovules. On ex- amining the leafy parts of the flower, they are seen to be six in number, very irregularly disposed. The three external ones, which are considered as the sepals of the calyx, are seen in the adjoining FIG. 188. A, FLOWER OF SPIDER ORCHIS, much figure (A) pointing UD- enlarged; B, ADHERENT ANTHER AND STIGMA, much ' , enlarged. wards and to the sides ; the two lateral ones in some species rise towards each other, and even meet and adhere, forming a sort of helmet-shaped arch, from beneath which the other parts of the flower project. The petals are also three, one of them being very much larger than the other two ; the two small ones are seen in the figure to point upwards and outwards, alternating with the sepals ; whilst the large one, pointing directly downwards, is that which has the greatest variety of form and colour in the different species, giving rise, by its curious metamorphoses, to the strange resemblances already alluded to. At the upper part of this transformed petal, which is termed the IdbeHum or lip, is an opening that leads in many of the species to a long spur that projects below. The other leafy portions of the flower are, in general, very delicately-coloured on their in- terior side. So far, the structure of the flowers is not very diffi- cult to understand, except in a few species in which the trans- formation is carried much farther. 694. The most remarkable peculiarity of the Orchideae, however, consists in that modification of the special organs of fructification, to which Linnaeus gave the name of gynandrous, and upon which he founded his twentieth class ; and, as this is STRUCTURE OF FLOWER OF ORCHIDEjE. 519 universal throughout the group, and exists in no other, and thus distinguishes the Orchideae from all other orders of the vegetable kingdom, the Linnaean class Gynandria exactly represents the order we are now considering. In the middle of the flower, just above the hole in the labellum which leads to the spur, half hidden by the petals, is a flat fleshy-looking body, represented on an enlarged scale, at B. The upper part of this is seen to be divided, by a channel down its middle, into two lobes, each of which is considerably swollen at one part of the side ; and over this swollen portion there is a fissure, running from one end of it to the other, which will open if the lobe be pressed. If the contents of this swelling be examined, they will be found to consist of an olive- green mass, composed of minute granules adherent together, and tapering gradually into a long stalk, by which it is attached. On examining the nature of these granules with the microscope, it is clearly seen that they are in reality pollen-grains ; and that thus the whole mass corresponds with the usual contents of an anther-lobe, in an adherent state. Hence it follows, that the whole of this curious structure is to be regarded as a metamor- phosed stamen ; the channel down its middle marking the division of the anther-lobes, and the fissures on the two sides being ana- logous to the suture or split, by which other anthers discharge their contents (. 433). On each side of the base of the anther is a little roundish knob, which has something of a granular character, and which is to be regarded as a rudimentary stamen. At the foot of the anther (lower part of B, Fig. 188) is a pale fleshy cup, one side of which is curved over its cavity ; this is called the hood ; and at the bottom of it is the viscid stigmatic surface. Here, then, we have the essential parts of the appa- ratus of fructification ; only one style and one stigma, however, being developed ; and these being adherent to one another. This latter character runs through the whole of the Orchideous group ; as to the former, however, there is some variation. Thus, in the Cypripedium, or Lady's Slipper, a British Orchideous plant, the two little prominences just mentioned are fully developed into stamens, whilst the central one, which is here developed, is rudi- 520 TUBEROUS ROOTS OF THE ORCHIDE.E. mentary ; and in some other species, all three are occasionally present as complete stamens. 695. There is much difficulty in understanding how the usual influence of the pollen on the stigma can be effected in these plants ; since the pollen is not capable of being scattered as a fine powder through the air, as in other plants ; and if it were to fall out in a mass, it would hardly touch the stigma. Some have supposed that absolute contact of the pollen with the stigma is not necessary, and have thought that the fertilising influence could be communicated through the stalk of the pollen-mass. But this is now proved to be incorrect; as numerous experiments have shown that the contact is as necessary here as in other plants. It is difficult to perceive, however, in what manner it is naturally effected ; and recourse has even been had to the sup- position, that the agency of insects is necessary, in order to drag the pollen-masses from their case, and to diffuse their granules over the stigma. 696. On turning our attention to the general aspect of either of our commoner British orchises, we observe that it has a fleshy root usually consisting of two oval tubers, and of a number of succulent fibres ; that its leaves, which have the simple- veined structure characteristic of Monocotyledons, spread upon the sur- face of the ground ; and that a straight flower-stalk is shot up from the midst of these. The stem and roots are connected with but one of the tubers ; the other arises as a sort of lateral bud from this one. When the stem has unfolded its flowers and ripened its fruit, it dies down to the ground, and is succeeded in the ensuing season by a stem developed from the second tuber, the first being exhausted. This, again, serves for the vegetation of one season only, and a new tuber is formed as a bud, from which the next year's stem will be developed. Hence the species possessing this kind of root, always have a pair of tubercles, one shrivelling and in process of exhaustion, the other swelling and in process of completion. Sometimes the bottom of the stem, instead of forming a new tuber upon its side, pushes out a slender subterranean root-like runner, which, after growing to some ORCHIS TRIBE; VANILLA, SALEP 521 length, is arrested and forms a tuber, from which the next stem is shot up ; so that the plant may be said to change its place every year to a considerable distance. In many instances, amongst exotic species, the tuber is formed above the ground, constituting what is known as the pseudo-bulb of the Orchideze ; and its horizontal stem creeps along the surface as a rhizoma. In these cases, the structures are more permanent, the pseudo-bulbs acquiring a woody hardness, and continuing to send up stems ; so that by their gradual multiplication, a large surface is often covered by a single plant. 697. It is remarkable that in a group so numerous as this, consisting as it does of nearly two thousand known species, and of probably as many more which, being buried in the depths of unexplored tropical forests, have not yet been described, and extending over almost the whole habitable globe, as far as the borders of the frozen zone, there should be so few species pos- sessed of properties, that make them in any way useful to Man. It often happens that the most powerful virtues, or the most deadly poisons, are hidden beneath a mean and insignificant exterior; whilst those productions of nature which charm the eye with their beauty, and delight the senses with their perfume, have the least relation with the wants of mankind. So it appears to be in this instance. The aromatic substance called Vanilla, which is sometimes used as an ingredient in chocolate, also to flavour sweet dishes, and to perfume snuff, is the succulent frwit of an Orchideous plant, which, in the "West Indies, creeps over trees and walls like ivy. A nutritive substance termed Salep, somewhat resembling Arrow-root or Sago, is obtained from the tubers of a species which grows in Turkey and Persia, where it is highly esteemed. It used to be sold at the corners of the streets in London, and was a favourite drink with porters, coal- heavers, and other hard-working people, by whom it was consi- dered very strengthening ; and the comparative disuse into which it has fallen is perhaps to be regretted. It is said to contain a greater amount of nutriment in the same buMf, than any othei- vegetable substance ; and for this reason it is much employed by 522 ORCHIS TRIBE; SALEP. GINGER TRIBE. travellers, who have to carry their supplies with them into deserts and uninhabited countries. So high a nutritive power has been assigned to it, that it has been asserted that one ounce of Salep, boiled with an equal quantity of the stiff glue or animal jelly known as portable soup, in two quarts of water, will suffice for the daily nourishment of an able-bodied man. Some of the South American species contain a viscid substance, which, when separated by boiling, serves as a sort of glue, which is used by the Brazilians for sticking together their skins of leather. There is scarcely any other way in which this order is of any direct utility to Man. 698. Of the next order, SCITAMINE^E, the Ginger tribe, there are no British representatives ; but its structure will be very easily comprehended, as we now return to a nearly regular type of structure. They are all aromatic herbaceous plants, only coming to perfection between the tropics ; and they are nearly all characterised by possessing a rhizoma, which creeps along the ground, and from the sides of which the leaf and flower-stalks are annually shot up. The flowers arise from expanded scaly bodies, which are clusters of bracts, one for the protection of each pair of buds. The ovarium, as in the Orchideas, is inferior ; and the calyx, which arises from its summit, is tubular, and is formed by three sepals adherent nearly to their points. Within this are two whorls of leafy organs, the outer of which is to be regarded as the true corolla, whilst the inner one consists of transformed stamens. In each whorl there are three segments ; those of the outer whorl, or petals, are partly adherent so as to form a tube, and are nearly equal one being sometimes larger than the rest or differently shaped, so as to show some affinity with the Orchideae. Of the inner whorl of transformed stamens, one is usually very much enlarged, like the labellum of Orchideae, whilst the others are almost undeveloped. Within this whorl, there are three distinct stamens, of which, however, only one usually bears pollen; but this is quite distinct from the pistil. The ovarium is usually three-celled, though sometimes im- perfectly so, the partitions not being complete, so as to ap- ORDER, SCITA MINE^E, OR LINGER TRIBE. 523 The style is long and proach that of the Orchideae in character, thread-like, dilated into an expanded stigma at the top. The fruit is gene- rally a three-celled capsule. 699. These plants are generally objects of great beauty, either on account of the high degree of development of the coloured parts of the flower itself, or be- cause of the rich and glowing hues of the bracts. They are, however, princi- pally valued on ac- count of the aro- matic and stimu- lating properties, FlG - H-GIN