^A^: \ .■p3 Digitized by the Internet Archive in 2010 with funding from Boston Library Consortium Member Libraries http://www.archive.org/details/formationofveget97darw THE FORMATION OF VEGETABLE MOULD THROUGH THE AOTIOI^ OF WOEMS. THE FOEMATION VEGETABLE MOULD, THROUGH THE ACTIOIT OF WOEMS, WITH OBSERVATIONS ON THEIR HABITS. CHARLES DARWIN, LL.D., F.R.S. T WITH ILL USTRA TJONS. BOSTON COLLFGK LIBRARY CHE8TNUT HILL, MA8S. NEW YORK : D. APPLETON AND COMPANY, 72 FIFTH AVENUE. 1897. Authorized Edition. 6til51 CONTENTS. INTRODUCTION T;iiS,e 1-7 O" CHAPTER I. HABITS OF WORMS. Nature of the sites inhabited — Can live long under water — Nocturnal — Wander about at night — Often lie close to the mouths of their burrows, and are thus destroyed in large numbers by birds — Structure — Do not possess eyes, but can distinguish between light and darkness— Eetreat rapidly when brightly illuminated, not by a reflex action — Power of atten- tion — Sensitive to heat and cold — Completely deaf — Sensitive to vibrations and to touch — Feeble power of smell — Taste — Mental qualities — Nature of food — Omnivorous — Digestion — Leaves before being swallowed, moistened with a fluid of the nature of the pancreatic secretion — Extra-stomachal digestion — Calciferons glands, structure of — Cal- caieous concretions formed in the anterior pair of glands — The calcareous matter primarily an excre- tion, but secondarily serves to neutralise the acids generated during the digestive process . 8-54 IV CONTENaS. CHAPTER 11. Habits of worms — contiuued. Manner in which worms seize objects — Their power of biintion — The instinct of plugging up the mouths of their burrows — Stones piled over the burrows — The advantages thus gained — Intelligence shown by worms in tbeir manner of plugging up their burrows ■r— Various kinds of leaves and other objects thus used — Triangles of paper — Summary of reasons for believing that worms exhibit some intelligence — Means by which they excavate their burrows, by pushing away the earth and swallowing it — Earth also swallowed fur the nutritious matter which it contains — Depth to which worms burrow, and the construction of their burrows — Burrows lined with castings, and in the upper part with leaves — The lowest part paved with little stones or seeds — Manner in which the castings are ejected — ^Tho collapse of old burrows — Distribution of worms — Tower-like castings in Bengal — Gigantic castings on the Kilgiri Mountains — Castings ejected in all countries . . ... . Page 55-128 CHAPTEE III. THE AMOUNT OF FINE EARTH BROUGHT UP BY WORMS TO THE SURFACE. Rate at which various objects strewed on the surface of grass-fields are covered up by the castings of worms — The burial of a paved path — The slow subsidence of great stones left on tne surface — The number of worms which live within a given space — The CONTENTS. V weight of earth ejected from a burrow, and from all tho burrows within a given space — The thickness (f tho layer of mould which the castings on a given space would form within a given time if uniformly spread out — The slow rate at which mould can increase to a great thickness — Conclusion Pagre 129-175 "&'■ CHAPTER IV. THE TAJ IT WHICH WORMS HAVE PLAYED IN THE BURIAL OF ANCIENT BUILDINGS. The accumulation of lubbish on the sites of great cities independent of the action of worms — Tho burial of a Eoman villa at Abinger — The floors and walls penetrated by worms — Subsidence of a modern pavement — The buried pavement at Beaulien Abbey — Eoman villas at Ched worth and Brading — The remains of the Eoman town at Silchester — Tho nature of the debris by which the remains are covered — The penetration of the tesselated floors and walls by worms — Subsidence of the fioors — Thickness of the mould — The old Eoman city of Wroxeter — Thickness of the mould — Depth of tho foundations of some of the buildings — Conclubion 17G-22D ghapt:se y. THE ACTION OF WORUS IN THE DENUDATION OF THE LAND. Sviience of the amount of denudation which the sand Las undergone — Subaerial denudation — The deposi- tion of dust — Vegetable mould, its dark coloar an.^ vi CONTENTS. fine texture largely due to the action of worms— j'he disintegration of rocks by the humus-acids — • Similar acids apparently generated within tlie bodies of worms — The action of these acids facilitated by the continued movement of the particles of earth — ^A thick bed of mould checks the disintegration of the underljdng soil and rocks — Particles of stone worn or triturated in tbe gizzards of worms — Swallowed stones serve as millstones — The levigated state of the castings — Fragments of brick in the castings over ancient buildings well rounded. The triturating power of worms not quite insignificant under a geological point of view . Page 230-258 CHAPTER YI. THE DENUDATION OF THE LAIHD— Continued, Denudation aided by recently ejected castings flowing down inclined grass-covered surfaces — The amount of earth which annually flows downwards — -The effect of tropical rain on worm castings — The finest particles of earth washed completely away from castings — The disintegration of dried castings into ]>ellets, and their rolling down inclined surfaces — The formation of little ledges on hill-sides, in part due to the accumulation of disintegrated castings — Castings blown to leeward over level land — An attempt to estimate the amount thus blown — The dogradation of ancient encampments and tumuli — The preservation of the crowns and furrows on land anciently p!oughed — The formation and amount of mould over the Chalk formation . . 259-304 CONTENTS. '«'" CHAPTER YII. C025CLUSION. Summary of the part which worms havo played in the history of the world — Their aid in the disintegra- tion of rocks — In the denudation of the land — Iii the preservation of ancient remains — In the pre- paration of the soil for the growth of plants — Mental powers of worms — Conclusion . 30«^-ol(i Index 315-326 THE FORMATION OF VEGETABLE MOULD, THROUGH THE ACTION OF WORMS, WITH OBSERVATIONS ON THEIR HABITS. INTRODUCTION. The share which worms have taken in the formation of the layer of vegetable mould, which covers the whole surface of the land in every moderately humid country, is the subject of the present volume. This mould is generally of a blackish colour and a few inches in thickness. In different districts it differs but little in appearance, although it may rest on various subsoils. The uniform fineness of the particles of which it is com- posed is one of its chief characteristic features ; and this may be well observed in any gravelly country, where a recently-ploughed field 2 INTRODUCTION. immediately adjoins one which has long re- mained undisturbed for pasture, and where the vegetable mould is exposed on the sides of a ditch or hole. The subject may appear an insignificant one, but we shall see that it possesses some interest 5 and the maxim " de minimis lex non curat," does not apply to science. Even Elie de Beaumont, who generally undervalues small agencies and their accumulated effects, remarks.* " la " couche tres-mince de la terre vegetale est un *' monument d'une haute antiquite, et^ par le '' fait de sa permanence, un objet digne d'oc- '' cuper le geologue, et capable de lui fournir ''des remarques interessantes." Although the superficial layer of vegetable mould as a whole no doubt is of the highest antiquity, yet in regard to its permanence, we shall here- after see reason to b,elieve that its component particles are in most cases removed at not a very slow rate, and are replaced by others due to the disintegration of the underlying materials. As I was led to keep in my study during many months worms in pots filled with earthy * ' Lecons de Geologie Pratique,' torn. i. 1845, p. 140 INTEODUCTION. 3 r became interested in them, and wished to learn how far they acted consciously, and how much mental power they displayed. I was the more desirous to learn something on this head, as few observations of this kind have been made, as far as I know, on animals so low in the scale of organization and so poorly provided with sense-organs, as are earth-worms. In the year 1837, a short paper was read by me before the Geological Society of London,* " On the Formation of Mould," in which it was shown that small fragments of burnt marl, cinders, Src, which had been thickly strewed over the surface of several meadows, were found after a few years lying at the depth of some inches beneath the turf, but still forming a layer. This apparent sinking of superficial bodies is due, as was first suggested to me by Mr. Wedgwood of Maer Hall in Staffordshire, to the large quantity of fine earth continually brought up to the surface by worms in the form ol castings. These castings are sooner or later * ' Transactions Geolog. Soc' vol. v. p. 505. Read Novem- ber 1. 1837. 4 INTKODUCTION. spread out and cover up any object left on the surface. I was thus led to conclude that all the vegetable mould over the whole coun* try has passed many times through, and will again pass many times through, the intestinal canals of worms. Hence the term "animal mould " would be in some respects more appropriate than that commonly used of *' vegetable mould." Ten years after the publication of my paper, M. D' Archiac, evidently influenced by the doc* trines of Elie de Beaumont, wrote about my "singuliere theorie," and objected that it could apply only to *'les prairies basses et humides;" and that "les terres labourees, les bois, les prairies elevees, n'apportent aucune preuve a Tappui de cette maniere de voir." * But M. D' Archiac must have thus argued from inner consciousness and not from observation, for worms abound to an extraordinary degree in kitchen gardens where the soil is continually worked, though in such loose soil they generally dejTosit their castings in any open cavities or within their old burrows instead of on the surface. Yon Hensen estimates that there are * • Histoire des progrfes de la Geologic,' torn. i. 1847, p. 224, INTRODUCTION. 5 about twice as many worms in gardens as in corn-field^,.* With respect to '* prairies elevees," I do not know how it may be in France, but nowhere in England have I seen the ground so thickly covered with castings as on commons, at a height of several hundred feet above the sea. In woods again, if the loose leaves in autumn are removed, the whole surface will be found strewed with castings. Dr. King, the superintendent of the Botanic Grarden in Calcutta, to whose kindness I am indebted for many observations on earth- worms, informs me that he found, near Nancy in France, the bottom of the State forests covered over many acres with a spongy layer, composed of dead leaves and innumerable worm-castings. He there heard the Professor of " Amenagement des Forets " lecturing to his pupils, and pointing out this case as a " beautiful example of the natural cultiva- '' tion of the soil ; for year after year the *' thrown-up castings cover the dead leaves ; *' the result being a rich humus of great *' thickness.'* * ' Zeitschrift fiir wissenschaft. Zoologl;,* B xxviii. 1877 p* 361. 6 INTRODUCTION. In tlie year 1869, Mr. Fish* rejected my conclusions with respect to the part which worms have played in the formation of veget- ahle mould, merely on account of their assumed incapacity to do so much work. He remarks that ''considering their weakness and their ' size, the work they are represented to " have accomplished is stupendous." Here wo have an instance of that inability to sum up the effects of a continually recurrent cause, which has often retarded the progress of science, as formerly in the case of geology, and more recently in that of the principle of evolution. Although these several objections seemed to me to have no weight, yet I resolved to make more observations of the same kind as those published, and to attack the problem on another side ; namely, to weigh all the cast- ings thrown up within a given time in a measured space, instead of ascertaining the rate at which objects left on the surface were buried by worms. But some of my observa- tions have been rendered almost superfluous by an admirable paper by Yon Hen sen, * ' Gardeners' Chrouicle,' April 17, 18G9, p. 418. IKTRODUTIOIS^. 7 already alluded to, whicli appeared in 1877. Before entering on details with respect to the castings, it will be advisable to give some account of the habits of worms from ray own observations and from those of other naturalists. HABITS OF WORMS. Chap. L CHAPTER I. HABITS OF WORMS. Nature of the sites inhabited — Can live long under water — Nocturnal — Wander about at night — Often lie close to the mouths of their burrows, and are thus destroyed in large numbers by birds — Structure — Do not possess eyes, but can distinguish between light and darkness — Retreat rapidly when brightly illuminated, not by a reflex action— Power of attention — Sensitive to heat and cold — Completely deaf — Sensitive to vibrations and to touch — Feeble povrer of smell — Taste — Mental qualities — Nature of food — Omnivorous — Digestion — Leaves before being swallowed, moistened with a fluid of the nature of the pancreatic secretion — Extra-stomachal digestion — Calciferous glands, structure of — Calcareous concretions formed in the anterior pair of glands — The calcareous matter primarily an excretion, but secondarily serves to neutralise the acids generated during the digestive process. Earth-worms are distributed throughout the world under the form of a few genera, which externally are closely similar to one another. The British species of Lumbricus have never been carefully monographed; but we may judge of their probable number from those inhabiting neighbouring countries. In Scan- dinavia there are eight species, according to Chap. I. SITES INHABITED. 9 Eisen ;* but two of these rarely burrow in the ground, and one inhabit?! very wet places oi even lives under the water. We are here t^oncerned only with the kinds which bring up earth to the surface in tlie form of cast- ings. Hoifmeister says that the species in Germany are not well known, but gives the same number as Eisen, together with some strongly marked varieties.! Earth-worms abound in England in many different stations. Their castings may be seen in extraordinary numbers on commons and chalk-downs, so as almost to cover the whole surface, wliere the soil is poor and the grass short and thin. But they are almost or quite as numerous in some of the London parks, where the grass grows well and the soil appears rich. Even on the same field worms are much more frequent in some places than in others, without any visible difference in the nature of the soil. They abound in paved court-yards close to houses ; and an instance will be given in which they had * 'Bidrag till Skandinaviens 01igoclia}tfauna,' 1871. t * Die bis jetzt bekaunten Arteu aus der Familie der Eegeii* ftli mer,' 184:5. 10 HABITS OF WOKMS. Chap. L burrowed through the floor of a very damp cellar. I have seen worms in black peat in a boggy field ; but they are extremely rare, or quite absent in the drier, brown, fibrous peaf, which is so much valued by gardeners. On dry, sandy or gravelly tracks, where heath with some gorse, ferns, coarse grass, moss and lichens alone grow, hardly any worms can be found. But in many parts of England, wherever a path crosses a heath, its surface becomes covered with a fine short sw^ard. Whether this change of vegetation is due to the taller plants being killed by the occasional trampling of man and animals, or to the soil being occasionally manured by the droppings from animals, I do not know.* On such grassy paths worm-castings may often be seen. On a heath in Surrey, which was carefully examined, there were only a few castings on these paths, where they were much inclined ; * There is even some reason to believe that pressure is actually favourable to the growth of grasses, for Professor Buckman, who made many observations on their growth in the experimental gardens of the Eoyal Agricultural College, remarks (' Gardeners' Chronicle,' 1854, p. 619) : " Another circumstance in the cultiva- tion of grasses in the separate form or small patches, is the impossibility of rolling or treading them firmly, vvithout whioli uo pasture can continue good." Chap. I. SITES INHABITED. II but on the more level parts, where a bed of fine earth had been washed down from the steeper parts and had accumulated to a thick- ness cfafew inches, worm-castings abounded. These spots seemed to be overstocked with worms, so that they had been compelled to spread' to a distance of a few feet from the grassy paths, and here their castings had been thrown up among the heath ; but beyond this limit, not a single casting could be found. A layer, though a thin one, of fine earth, which probably long retains some moisture, is in all cases, as I believe, necessary for their existence ; and the mere compression of the soil appears to be in some degree favourable to them, for they often abound in old gravel walks, and in foot-paths across fields. Beneath large trees few castings can be found during certain seasons of the year, and this is apparently due to the moisture having been sucked out of the ground by the innu- merable roots of the trees ; for such places may be seen covered with castings after the heavy autumnal rains. Although most cop- pices and woods support many worms, yet in a forest of tall and ancient beech-trees in Knole 12 HABITS OF WORMS. Chap. I. Park, where the ground beneath was bare of all vegetation, not a single casting could be fDund over wide spaces, even during the autumn. Nevertheless, castings were abun- dant on some grass-covered glades and in- dentations which penetrated this forest. On the mountains of North Wales and on the Alps, worms, as I have been informed, are in most places rare ; and this may perhaps be due to the close proximity of the sub- jacent rocks, into which worms cannot burrow during the winter so as to escape being frozen. Dr. Mcintosh, however, found worm-castings at a height of 1500 feet on Schiehallion in Scotland. They are numerous on some hills near Turin at from. 2000 to 3000 feet above the sea, and at a great altitude on the Nilgiri Mountains in South India and on the Himalaya. Earth-worms must be considered as terres- trial animals, though they are still in one sense semi-aquatic, like the other members of the great class of annelids to which they belong. M. Perrier found that their ex- posure to the dry air of a room for only a single night was fatal to them. On the Ohap. I. NOCTUENAL. 13 other hand he kept several large worms alive for nearly four months, completely submerged in water.* During the summer when the ground is dry, they penetrate to a consider- able depth and cease to work, as they do during the winter when the ground is frozen. Worms are nocturnal in their habits, and at night may be seen crawling about in large numbers, but usually with their tails still inserted in their burrows. By the expansion of this part of their bodies, and with the help of the short, slightly reflexed bristles, with which their bodies are armed, they hold so fast that they can seldom be dragged out of the ground without being torn into pieces.f During the day they remain in their burrows, except at the pairing season, when those which inhabit adjoining burrows expose the greater part of their bodies for an hour or two in the early morning. Sick * I shall have occasion often to refer to M. Perricr's admirable memoir, 'Organisation des Lombriciens terrestres' in 'Archives de Zoolcg. exper.' torn. iii. 1874, p. 372. 0. F. Morren (' De Lumbrici terrestris,' 1829, p. 14) fouud that worms endured immersion for fifteen to twenty days in summer, but that ia vi'inter they died when thus treated. t Morren, 'De Lumbrici terrestris,' &c., 1829, p. 67. 14 HABITS OF WORMS. CnAr. 1. individuals, which are generally affected by the parasitic larvae of a fly, must also be ex- cepted, as they wander about during the day and die on the surface. After heavy rain succeeding dry weather, an astonishing num- ber of dead worms may sometimes be seen lying on the ground. Mr. Galton informs me that on one such occasion (March, 1881), the dead worms averaged one for every two and a half paces in length on a walk in Hyde Park, four paces in width. He counted jio less than 45 dead worms in one place in a length of sixteen paces. From the facts above given, it is not probable that these worms could have been drowned, and if they had been drowned they would have perished in their burrows. I believe that they were already sick, and that their deaths were merely hastened by the ground being flooded. It has often been said that under ordinary circumstances healthy worms never, or very rarely, completely leave their burrows at night ; but this is an error, as White of Sel- borne long ago knew. In the morning, aftei there has been heavy rain, the film of mud or of very fine sand over gravel-w^alks is often Chap. I. WANDEK FKOM THEIR BUEROWS. 15 plainly marked witli their tracks. I have ijoticed this from August to May, both months included, and it probably occurs during the two remaining months of the year when they are wet. On these occasions, very few dead worms could anywhere be seen. On January 31, 1881, after a long-continued and unusually severe frost with much snow, as soon as a thaw set in, the walks were marked with innumerable tracks. On one occasion, five tracks were counted crossing a space of only an inch square. They could sometimes be traced either to or from the mouths of the burrows in the gravel-walks, for distances between 2 or 3 up to 15 yards. I have never seen two tracks leading to the same burrow ; nor is it likely, from what we shall presently see of their sense-organs, that a worm could find its way back to its burrow after having once left it. They apparently leave their burrows on a voyage of discovery, and thus they find new sites to inhabit. Morren states * that worms often lie for hours almost motionless close beneath the mouths of their burrows. I have occasionally Qoticed the same fact with worms kept in * ' Do Liimbrici terrestris,' &c., p. 14. 16 HABITS OF WORMS. Chap. 1 pots in the house ; so that by looking down into their burrows, their heads could just be seen. If the ejected earth or rubbish over the barrows be suddenly removed, the end of the worm's body may very often be seen rapidly retreating. This habit of lying near the surface leads to their destruction to an immense extent. Every morning during cer- tain seasons of the year, the thrushes and blackbirds on all the lawns throughout the country draw out of their holes an astonishing number of worms ; and this they could not do, unless they lay close to the surface. It is not probable that worms behave in this manner for the sake of breathing fresh air, for we have seen that they can live for a long time under water. I believe that they lie near the surface for the sake of warmth, es- pecially in the morning ; and we shall here- after find that they often coat the mouths of their burrows with leaves, apparently to prevent their bodies from coming into close contact with the cold damp earth. It is said that they completely close their burrows during the winter. Structure, — A few remarks must be made on this subject. The body of a large worm Chap. J. THEIR STRUCTURE. 17 consists of from 100 to 200 almost cylindrical rings or segments, each furnished with minute bristles. The muscular system is well developed. Worms can crawl backwards as well as forwards, and by the aid of their affixed tails can retreat with extraordinary rapidity into their burrows. The mouth is situated at the anterior end of tlie body, and is provided with a little projection (lobe or lip, as it has been variously called) which is used for prehension. Internally, behind the mouth, there is a strong pharynx, shown in the ac- companying diagram (Fig. 1) which is pushed forwards when the animal eats, and this part corresponds, according to Perrier, with the pro- trudable trunk or proboscis of other annelids. The pharynx leads into the oesophagus, on each side of which in the lower part there are three pairs of large glands, which secrete a surprising amount of carbonate of lime. These calciferous glands are highly remark- able, for nothing like them is known in any other animal. Their use will be discussed when we treat of the digestive process. In most cf the species, the oesophagus is enlarged into a crop in front of the gizzard. This 18 HABITS OF WORMS. Chap. L latter organ is Mout'i. Pharynx. (Esophagus. Calciferous glands. Esophagus. Crop. Gizzaid. 1^^ Upper part of testin.\ Fig . 1. Diagram of the alimen- tary canal of an earth- worm (Lumhricus), copied from Ray Lan- kester in ' Quart. Journ. of Microscop. Soc' vol. XV. N.S. pi. vii. lined with a smooth thick chitinous membrane, and is surrounded by weak longitudinal, but by power- ful transverse muscles. Perrier saw these muscles in energetic action; and, as he remarks, the trituration of the food must be chiefly eflected by this organ, for worms possess no jaws or teeth of any kind. Grains of sand and small stones, from the 2V ^^ ^ little more than the ^^ inch in diameter, may generally be found in their gizzards and intestines. As it is certain that worms swal- low many little stones, in- dependently of those swal- lowed while excavating their burrows, it is prob- able that they serve, like mill-stones, to triturate their food. The gizzard opens into tlie intestine, Chap. I. THEIR SENSES. 19 which runs in a straight course to the vent at the posterior end of the body. The intes- tine presents a remarkable structure, the typhosohs, or, as the old anatomists called it, an intestine within an intestine ; and Clapa- rede* has shown that this consists of a deep longitudinal involution of the walls of the intestine, by which means an extensive absorbent surface is gained. The circulatory system is well developed. Worms breathe by their skin, as they do not possess any special respiratory organs. The two sexes are united in the same individual, but two individuals pair together. The nervous system is fairly well developed ; and the two almost confluent cerebral ganglia are situated very near to the anterior end of the body. Senses, — Worms are destitute of eyes, and at first I thought that they wxre quite in- sensible to light ; for those kept in confine- ment were repeatedly observed by the aid of a candle, and others out of doors by the aid of a lantern, yet they were rarely alarmed, although extremely timid animals. Other * Histolog. Untersucliungeii iiber die Eegenwiirmer. *Zcit- schrift fiir wissenschaft. Zoologie/ B. xix., 1869, p. 611. 20 HABITS OF WORMS. Cuap. L persons have found no difficuity in observing worms at niglit by the same means.* Hoffmeister, however, states f that worms, with the exception of a few individuals, are extremely sensitive to light ; but he admits that in most cases a certain time is requisite for its action. These statements led me to watch on many successive nights worms kept in pots, which were protected from currents of air by means of glass plates. The pots were approached very gently, in order that no vibration of the floor should be caused. When under these circumstances worms were illuminated by. a bull's-eye lantern having slides of dark red and blue glass, which in- tercepted so much light that they could be seen only with some difficulty, they were not at all affected by this amount of light, however long they were exposed to it. The light, as far as I could judge, was brighter than that from the full moon. Its colour apparently made ao difference in the result. When they were * For instance, Mr. Bridgman and Mr. Newman (' The Zoologist/ vol. vii. 1849, p. 2576), and some friends who observtvi worms for me. t ' Familie der Regenwiirmer,' 1845, p. 18. Chap. I. THEIR SENSES. 2i illuminated by a candle, or even by a bright paraffin lamp, tbey were not usually affected at first. Nor were they when the light was alternately admitted and shut off. Some- times, however, they behaved very differ- ently, for as soon as the light fell on them, they withdrew into their burrows with almost instantaneous rapidity. This occurred perhaps once out of a dozen times. When they did not withdraw instantly, they often raised the anterior tapering ends of their bodies from the ground, as if their attention was aroused or as if surprise was felt ; or they moved their bodies from side to side as if feeling for some object. They appeared distressed by the light ; but I doubt whether this was really the case, for on two occasions after withdrawing slowly, they remained for a long time with their anterior extremities protruding a little from the mouths of their burrows, in which position they were readv for instant and complete withdrawal. When the light from a candle was con- centrated by means of a large lens on the anterior extremity, they generally withdrew instantly ; but this concentrated light failed 22 HABITS OF WORMS. Chap. 1 to act perhaps once out of half a dozen trials. The light was on one occasion concentrated on a worm lying beneath water in a saucer^ and it instantly withdrew into its burrow. In all cases the duration of the light, unless extremely feeble, made a great difference in the result ; for worms left exposed before a paraffin lamp or a candle invariably retreated into their burrows within from five to fifteen minutes ; and if in the evening the pots were illuminated before the worms had come out of their burrows, they failed to appear. From the foregoing facts it is evident that light affects worms by its intensity and by its duration. It is only the anterior extremity of the body, where the cerebral ganglia lie, which is affected by light, as Hoffmeister asserts, and as I observed on many occasions. If this part is shaded, other parts of the body may be fully illuminated, and no effect will be produced. As these animals have no eyes, we must suppose that the light passes through their skins, and in some manner excites their cerebral ganglia. It appeared at first probable that the dif- ferent manner in which they were affected on Chap. L THEIE SENSES. 23 different occasions miglit be explained, either by the degree of extension of their skin and its consequent transparency, or by some particular incidence of the liglit ; but I could discover no such relation. One thing was manifest, namely that when worms were employed in dragging leaves into their burrows or in eating them, and even during the short intervals whilst they rested from their work, they either did not perceive the light or were regardless of it ; and this occurred even when the light was concentrated on them through a large lens. So, again, whilst they are paired, they will remain for an hour or two out of their burrows, fully exposed to the morning light ; but it appears from what Hoffmeister says that a light will occasionally cause paired individuals to separate. When a worm is suddenly illuminated and dashes like a rabbit into its burrow — to use the expression employed by a friend — we are at first led to look at the action as a reflex one. The irritation of the cerebral ganglia appears to cause certain muscles to contract in an inevitable mann^^r, independently of the will 3 24 HABITS OF WORMS. Chap. I or consciousness of the animal, as if it were an automaton. But the different effect which a h'ght produced on different occasions; and especially the fact that a worm when in any way employed and in the intervals ol such employment, whatever set of muscles and ganglia may then have been brought into j)lay, is often regardless of light, are opposed to the view of the sudden withdrawal being a simple reflex action. With the higher animals, when close attention to some object leads to the disregard of the impressions which other objects must be producing on them, we attribute this to their attention being then absorbed ; and attention implies the presence of a mind. Every sportsman knows that he can approach animals whilst they are grazing, fighting or courting, much more easily than at other times. The state, also, of the nervous system of the higher animals differs much at different times, for instance, a horse is much more readily startled at one time than at another. The comparison here implied between the actions of one oJ the higher animals and of one so low in the scale as an earth-w^orm, may appear far- Chap. I. THEIR SENSES. 25 fetched ; for we tlms attribute to the worm attention and some mental power, neverthe- less I can see no reason to doubt the justice of the comparison. Although worms cannot be said to possess the power of vision, their sensitiveness to light enables them to distinguish between day and night ; and they thus escape extreme danger from the many diurnal animals which prey on them. Their withdrawal into their burrows during the day appears, however, to have become an habitual action ; for worms kept in pots covered by glass-plates, over which sheets of black paper were spread, and placed before a north-east win- dow, remained during the day-time in their burrows and came out every night ; and they continued thus to act for a week. No doubt a little light may have entered between the sheets of glass and the blackened paper ; but we know from the trials with coloured glass, that worms are indifferent to a small amount of light. Worms appear to be less sensitive to moderate radiant heat than to a bright light. I judge of this from having held at diflferent 26 HABITS OF WORMS. CiiAP. L times a poker heated to dull redness near some worms, at a distance which caused a very sensible degree of warmth in my hand* One of them took no notice ; a second with- drew into its burrow, but not quickly; the third and fourth much more quickly, and the fifth as quickly as possible. The light from a candle, concentrated by a lens and passing through a sheet of glass which would intercept most of the heat-rays, generally caused a much more rapid retreat than did the heated poker. Worms are sensitive to a low temper- ature, as may be inferred from their not coming out of their burrows during a frost. Worms do not possess any sense of hearing. They took not the least notice of the shrill notes from a metal whistle, which was re- peatedly sounded near them ; nor did they of the deepest and loudest tones of a bassoon. They were indifferent to shouts, if care was taken that the breath did not strike them. When placed on a table close to the keys oi a piano, which was played as loudly as possible^ they remained perfectly quiet. Although they are indifferent to undula- tions in the air audible by us, they are Chap. I. THEIR SENSES. 27 extremely sensitive to vibrations in any solid object. When the pots containing two worms which had remained quite indifferent to the sound of the piano, were placed on this instrument, and the note C in the bass clef was struck, both instantly retreated into their burrows. After a time they emerged, and when Gr above the line in the treble clef was struck they again retreated. Under similar circumstances on another night one worm dashed into its burrow on a very high note being struck only once, and the other worm when C in the treble clef was struck. On these occasions the worms were not touching the sides of the pots, which stood in saucers ; so that the vibrations, before reaching their bodies, had to pass from the sounding board of the piano, through the saucer, the bottom of the pot and the damp, not very compact earth on which they lay with their tails in their burrov/s. They often showed their sensitiveness when the pot in which they lived, or the table on which the pot stood, was accidentally and lightly struck ; but they appeared less sensi- tive to such jars than to the vibrations of the 28 HABITS OF WORMS. Chap. F. piano ; and their sensitiveness to jars varied mnch at different times. It has often been said that if the ground is beaten or otherwise made to tremble, worms believe that they are pursued by a mole and leave their burrows. I beat the ground in many places where worms abounded, but not one emerged. When, however, the ground is dug with a fork and is violently disturbed beneath a worm, it will often crawl quickly out of its burrow. The whole body of a worm is sensitive to contact. A slight puff of air from the mouth causes an instant retreat. The glass plates placed over the pots did not fit closely, and blowing through the Yery narrow chinks thus left, often sufficed to cause a rapid retreat. They sometimes perceived tlie eddies in the air caused by cpickly removing the glass plates. When a worm first comes out of its burrow, it generally moves the much ex- tended anterior extremity of its body from side to side in all directions, apparently as an organ of touch ; and there is some reason to believe, as we shall see in the next chapter, that they are thus enabled to gain a general Chap. I. THEIR SENSES. 29 notion of the form of an object. Of all tlieir senses that of touch, including in this term the perception of a vibration, seems much the most highly developed. In worms the sense of smell apparently is confined to the perception of certain odours, and is feeble. They were quite indifferent to my breath, as long as I breathed on them very gently. This was tried, because it appeared possible that they might thus be warned of the approach of an enemy. They exhibited the same indifference to my breath whilst I chewed some tobacco, and while a pellet of cotton-wool with a few drops of mille-fleurs perfume or of acetic acid was kept in my mouth. Pellets of cotton-wool soaked in tobacco juice, and in millefleurs perfume, and in paraffin, were held with pincers and were waved about within two or three inches of several worms, but they took no notice. On one or two occasions, however^ when acetic acid had been placed on the pellets, the worms appeared a little uneasy, and this was probably due to the irritation of their skins. The perception of such unnatural odours would be of no service to worms ; and as such 30 HABITS OF WORMS. Chap. L timid creatures would almost certainly exhibit some signs of any new impression, we may conclude that they did not perceive these odours. The result was different when cabbage- leaves and pieces of onion were employed, both of which are devoured with much relish by worms. Small square pieces of fresh and half-decayed cabbage-leaves and of onion bulbs were on nine occasions buried in my pots, beneath about i of an inch of common garden soil ; and they were always discovered by the worms. One bit of cabbage was dis- covered and removed in the course of two hours ; three were removed by the next morning, that is, after a single night ; tv*^o others after two nights ; and the seventh bit after three nights. Two pieces of onion were discovered and removed after three nights. Bits of fresh raw meat, of which worms are very fond, were buried, and were not dis- covered within forty-eight hours, during which time they had not become putrid. The earth above the various buried objects was generally pressed down only slightly, so as not to prevent the emission of any odour. Chjip. I. THEIR SENSES. 31 On two occasions, however, the surface was well watered, and was thus rendered some- what compact. After the bits of cabbage and onion had been remcved, I looked beneath them to see whether the worms had acci- dentally come up from below, but there was no sign of a burrow; and twice the buried objects were laid on pieces of tin-foil which were not in the least displaced. It is of course possible that the worms whilst moving about on the surface of the ground, with their tails affixed within their burrows, may have poked their heads into the places where the above objects were buried ; but I have never seen worms acting in this manner. Some pieces of cabbage-leaf and of onion were twice buried beneath very fine ferruginous sand, which was slightly pressed down and well watered, so as to be rendered very compact, and these pieces were never discovered. On a third occasion the same kind of sand was neither pressed down nor watered, and the pieces of cabbage were discovered and re- moved after the second night. These several facts indicate that worms possess some power of smell ; and that they discover by thia 32 HABITS OF WORMS. Chap. L means odoriferous and mucli-coveted kinds of food. It may be presumed that all animals which feed on various substances possess the sense of taste, and this is certainly the case with worms. Cabbage-leaves are much liked by worms ; and it appears that they can dis- tinguish between different varieties ; but this may perhaps be owing to differences in their texture. On eleven occasions pieces of the fresh leaves of a common green variety and of the red variety used for pickling w^ere given them, and they preferred the green, the red being either wholly neglected or much less gnawed. On two other occasions, how ever, they seemed to prefer the red. Half- decayed leaves of the red variety and fresh leaves of the green were attacked about equally. When leaves of the cabbage, horse- radish (a favourite food) and of the onion were given together, the latter were always and manifestly preferred. Leaves of the cabbage, lime-tree, Ampelopis, parsnip (Pastinaca), and celery (Apium) were likewise given together; and those of the celery were first eaten. But when leaves of cabbage, turnip^ beet, celery, Chap. I. THEIR SENSES. 33 wild cherry and carrots were given together, the two latter kinds, especially those of the carrot, were preferred to all the others, including those of celery. It was also mani- fest after many trials that wild cherry leaves were greatly preferred to those of the lime- tree and hazel (Corylus). According to Mr. Bridgman the half-decayed leaves of Phlox verna are particularly liked by worms.* Pieces of the leaves of cabbage, turnip, horse-radish and onion were left on the pots during 22 days, and were all attacked and had to be renewed ; • but during the w^hole of this time leaves of an Artemisia and of the culinary sage, thyme and mint, mingled with the above leaves, were quite neglected excepting those of the mint, which were occa- sionally and very slightly nibbled. These latter four kinds of leaves do not differ in texture in a manner which could make them disagreeable to worms ; they all have a strong taste, but so have the four first mentioned kinds of leaves ; and the wide difference in the result must be attributed to a preference m the worms for one taste over another. The Zoologist; vol. vii, 184D, p. 2576. 34 HABITS OF WOE^IS. Chzlp. I, Mental Qualities. — There is little to be said on this head. We bav^e seen tbat worms are timid. It may be doubted whether they suffer as much pain when injured, as they seem to express by their contortions. Judging by their eagerness for certain kinds of food, they must enjoy the pleasure of eating. Their sexual passion is strong enough to overcome for a time their dread of light. They perhaps have a trace of social feeling, for they are not disturbed by crawling over each other's bodies, and they sometimes lie in contact. According to Hoffmeister they pass the winter either singly or rolled up with others into a ball at the bottom of their burrows.* Although worms are so remark- ably deficient in the several sense-organs, this does not necessarily preclude intelligence, as we know from such cases as those of Laura Bridgman; and we have seen that when theii attention is engaged, they neglect impressions to which they would otherwise have attended ; and attention indicates the presence of a mind of some kind. They are also much more easily excited at certain times than at others. * ' Familie rir.r Regenwiirmcr,' p. 13. Chap. I. MENTAL QUALITIES. 35 They perform a few actions instinctively, that is, all the individuals, including the young, perform such actions in nearly the same i'ashion. This is shown by the manner in which the species of Perichseta eject their castings, so as to construct towers; also by the manner in which the burrows of the common earth-worm are smoothly lined with fine earth and often with little stones, and the mouths of their burrows with leaves. One of their strongest instincts is the plug- ging up the mouths of their burrows with various objects ; and very young worms act in this manner. But some degree of in- telligence appears, as we shall see in the next chapter, to be exhibited in this work, — a result which has surprised me more than anything else in regard to worms. Food and Digestion. — Worms are omnivo- rous. They swallow an enormous quantity of earth, out of which they extract any diges- tible matter which it may contain ; but to this subject I must recur. They also con- sume a large number of half-decayed leaves of all kinds, excepting a few which have an unpleasant taste or are too tough for them : 36 HABITS OF WORMS. Chap. 1 likewise petioles, peduncles and decayed flowers. But they will also consume fresh leaves, as T have found by repeated trials. According to Morren* they will eat particles of sugar and liquorice ; and the worms which I kept drew many bits of dry starch into their burrows, and a large bit had its angles well rounded by the fluid poured out of their mouths. But as they often drag particles of soft stone, such as of chalk, into their burrows, I feel some doubt whether the starch was used as food. Pieces of raw and roasted meat were fixed several times by loug pins to the surface of the soil in my pots, and night after night the worms could be seen tugging at them, with the edges of the pieces engulfed in their mouths, so that much was consumed. Raw fat seems to be preferred even to raw meat or to any other substance which was given them, and much was consumed. They are cannibals, for the two halves of a dead worm placed in two of the pots were dragged into the burrows and. gnawed ; but as far as I could judge, they prefer fresh to putrid meat, and in so far I differ from Hofirneister. * ' De Lumbrici terrestris ' p. 19. CiiAP. I. FOOD AND DIGESTION. 37 Leon Fredericq states* that tlie digestive fluid of worms is of tlie same natm^e as the pancreatic secretion of the higher animals ; and this conclusion agrees perfectly with the kinds of food which worms consume. Pan- creatic juice emulsifies fat, and we have just seen how greedily worms devour fat ; it dissolves fibrin, and worms eat raw meat ; it converts starch into grape-sugar with wonder- ful rapidity, and vtq shall presently show that the digestive fluid of worms acts on starch.f But they live chiefly on half-decayed leaves ; and these would be useless to them unless they could digest the cellulose forming the cell- walls ; for it is well known that all other nutri- tious substances are almost completely with- drawn from leaves, shortly before they fall off. It has, however, now been ascertained that cellulose, though very little or not at all attacked by the gastric secretion of the higher animals, is acted on by that from the pancreas. J • * Arcliives de Zoologie experimentale/ torn. vii. 1878, p. 394. t On the action of the pancreatic ferment, see * A Text-Book cf Physiology,' by Michael Foster, 2n(i edit. pp. 198-203. 1878. X Schmulewitsch, ' Action des Sues digestifs sur la Cellulose. Bull, de I'Acad. Imp. de St. Pe'teisbourg, torn. xxv. p. 549. 1879. 38 HABITS OF WORMS. Chap. 1 The half-decayed or fresh leaves which worms intend to devour, are dragged into the mouths of their burrows to a depth of from one to three inches, and are then moistened with a secreted fluid. It has been assumed that this fluid serves to hasten their decay ; but a large number of leaves were twice pulled out of the burrows of worms and kept for many weeks in a Yerj rnoist atmosphere under a bell-glass in my study ; and the parts which had been moistened by the worms did not decay more quickly in any plain manner than the other parts. When fresh leaves were given in the evening to worms kept in confinement and examined early on the next morning, therefore not many hours after they had been dragged into the burrows, the fluid with which they were moistened^ when tested with neutral litmus paper, showed an alkaline reaction. This was repeatedly found to be the case with celery, cabbage and turnip leaves. Parts of the same leaves which had not been moistened by the worms, were pounded with a few drops of distilled water, and tlie juice thus extracted was not alkaline. Some leaves, however, which had been drawn CiiAP. I. FOOD AND DIGESTION. 39 into burrows out of doors, at an unknown antecedent period, were tried, and though still moist, they rarely exhibited even a trace of alkaline reaction. The fluid, with which the leaves are bathed, acts on thein whilst they are fresh or nearly fresh, in a remarkable manner ; for it quickly kills and discolours them. Thus the ends of a fresh carrot-leaf, which had been dragged into a burrow, were found after twelve hours of a dark brown tint. Leaves of celery, turnip, maple, elm, lime, thin leaves of ivy, and occasionally those of the cabbage were similarly acted on. The end of a leaf of Triticum repens^ still attached to a growing plant, had been drawn into a burrow, and this part was dark brown and dead, whilst the rest of the leaf was fresh and green. Several leaves of lime and elm removed from burrows out of doors were found affected in different degrees. The first change appears to be that the veins become of a dull reddish-orange. The cells with chlorophyll next lose more or less completely their green colour, and their contents finally become brown. The parts thus affected often appeared almost black by 4:0 HABITS OF WORMS. Cuap. L reflected light; but when viewed as a trans- parent object under the microscope, minute specks of h'ght were transmitted, and this was not the case with the unaffected parts of the same leaves. These effects, how^- ever, merely show that the secreted fluid is highly injurious or poisonous to leaves ; for nearly the same effects were produced in from one to two days on various kinds of young leaves, not only by artificial pancreatic fluid, prepared with or without thymol, but quickly by a solution of thymol by itself. On one occasion leaves of Corylus were much dis- coloured by being kept for eighteen hours in pancreatic fluid, without any thymol. With young and tender leaves immersion in human saliva during rather warm weather, acted in the same manner as the pancreatic fluid, but not so quickly. The leaves in all these cases often became infiltrated with the fluid. Large leaves from an ivy plant growing on a wall were so tough that they could not be gnawed by worms, but after four days Ihey were affected in a peculiar manner by the secretion poured out of their mouths. The upper surfaces of the leaves, over which the Chap. I. FOOD AND DIGESTION. 41 worms had crawled, as was sliown by the dirt left on them, were marked in sinuous lines, by either a continuous or broken chain of whitish and often star-shaped dots, about 2 mm. in diameter. The appearance thus pre- sented was curiously like that of a leaf, into which the larva of some minute insect had burrowed. But my son Francis, after making and examining sections, could nowhere find that the cell-walls had been broken down or that the epidermis had been penetrated. When the section passed through the whitish dots, the grains of chlorophyll were seen to be more or less discoloured, and some of the palisade and mesophyll cells contained nothing but broken down granular matter. These effects must be attributed to the trans- udation of the secretion through the epidermis into the cells. The secretion with which worms moisten leaves likewise acts on the starch granules within the cells. My son examined some leaves of the ash and many of the lime, which had fallen off the trees and had been partly dragged into worm-burrows. It is known that with fallen leaves the starch- 42 HABITS OF WOEMS. Chap. L grains are preserved in the guard-cells of tlie storaata. Now in several cases the starch had partially or wholly disappeared from these cells, in the parts which had been moistened by tlie secretion ; while they were still well pre- served in the other parts of the same leaves. Sometimes the starch was dissolved out of only one of the two guard- eel Is. The nucleus in one case had disappeared, together with the starch-granules. The mere burying of lime-leaves in damp earth for nine days did not cause the destruction of the starch- granules. On the other hand, the immersion of fresh lime and cherry leaves for eighteen hours in artificial pancreatic fluid, led to the dissolution of the starch-granules in the guard- cells as well as in the other cells. From the secretion with which the leaves are moistened being alkaline, and from its acting both on the starch-granules and on the protoplasmic contents of the cells, we may infer that it resembles in nature not saliva,* but pancreatic secretion ; and we know from Fredericq that a seci^etion of tiiis * C/laparede doubts whether saliva is secretea by worms : see Zeitschiift fiir wissenschaft. Zoologie,' P>. xix. 1869, p. GOl. Chap. I. CALCIFEROUS GLANDS. 43 kind is found in the intestines of worms. As the leaves whicli are dragged into tlie bur- rows are often dry and shrivelled, it is in- dispensable for their disintegration by the unarmed mouths of worms that they should first be moistened and softened ; and fresh leaves, however soft and tender they may be, are similarly treated, probably from habit. The result is that they are partially digested before they are taken into the alimentary canal. I am not aware of any other case of extra-stomachal digestion having been re- corded. The boa-constrictor bathes its prey with saliva^ but this is solely for lubricating it. Perhaps the nearest analogy may be found in such plants as Drosera and Dionasa ; for here animal matter is digested and con- verted into peptone not within a stomach, but on the surfaces of the leaves. Calciferous Glaiids. — These glands (see Fig. 1), judging from their size and from their rich supply of blood-vessels, must be of much importance to the animal. But almost aa many theories have been advanced on their use as there have been observers. They consist of three pairs, which in the common 14 HABITS OF WORMS. Chap. T. earth-worm debouch into the ahmentary canal in advance of the gizzard, but pos- teriorly to it in Urochtsea and some other genera.* The two posterior pairs are formed by lamellge, which according to Claparede, are diverticula from the oesophagus. y These lamellae are coated with a pulj)y cellular layer, with the outer cells lying free in in- finite numbers. If one of these glands is punctured and squeezed, a quantity of white pulpy matter exudes, consisting of these free cells. They are minute, and vary in diameter from 2 to 6 /^. They contain in their centres a little excessively fine granular matter; but they look so like oil globules that Claparede and others at first treated them with ether. This produces no effect ; but they are quickly dissolved with effervescence in acetic acid, and when oxalate of ammonia is added to the solution a white precipitate is thrown down. We may therefore conclude that they contain carbonate of lime. If the cells * Perrier, ' Archives de Zoolog. exp^r,' July, 1874, pp. 416, 419. t ' Zeitschrift fiir wissenschaft. Zoologie,' B. xix. 18G9, pp, 603-606. Chap. I. CALCIFEROUS GLANDS. 45 are immersed in a very little acid, they become more transparent, look like ghosts, and are soon lost to view ; but if much acid is added, they disappear instantly. After a very large number have been dissolved, a flocculent residue is left, which apparently consists of the delicate ruptured cell-walls. In the two posterior pairs of glands the carbonate of lime contained in the cells oc- casionally aggregates into small rhombic crystals or nito concretions, which lie be- tween the lamellae ; but I have seen only one, and Claparede only a very few such cases. The two anterior glands differ a little in shape from the four posterior ones, by being more oval. They differ also conspicuously in generally containing several small, or two or three larger, or a single very large concre- tion of carbonate of lime, as much as IJ mm. in diameter. When a gland includes only a few very small concretions, or, as sometimes happens, none at all, it is easily overlooked. The large concretions ai'e round or oval, and exteriorly almost smooth. One was found which filled up not only the whole gland, as is often the case, but its neck ; so that it 46 HABITS OF WORMS. Chap. L resembled an olive-oil flask in shape. These concretions when broken are seen to be more or less crystalline in structure. How they escape from the gland is a marvel ; but tliat they do escape is certain, for they are often found in the gizzard, intestines, and in the castings of worms, both with those kept in confinement and those in a state of nature. Claparede says very little about the structure of the two anterior glands, and he supposes that the calcareous matter of which the concretions are formed is derived from the four posterior glands. But if an anterior gland which contains only small concretions is placed in acetic acid and afterwards dissected, or if sections are made of such a gland without being treated with acid, lamellae like those in the posterior glands and coated with cellular matter could be plainly seen, together with a multitude of free calciferous cells readily soluble in acetic acid. When a gland is completely filled with a single large concretion, there are no free cells, as these have been all consumed in forming the concretion. But if such a c(m- <^nAP. I. CALCIFEllOUS GLANDS. 47 cretion, or one of only moderately large size is dissolved in acid, mncli membranous matter is left, which appears to consist of the remains of the formerly active lamellae. After the formation and expulsion of a large concretion, new lamellae must be developed in some manner. In one section made by my son, the process had apparently commenced, although the gland contained two rather large concre- tions, for near the walls several cylindrical and oval pipes were intersected, which were lined with cellular matter and were quite filled with free calciferous cells. A great enlargement in one direction of several oval pipes would give rise to the lamellse. Besides the free calciferous cells in which no nucleus was visible, other and rather larger free cells were seen on three occasions ; and these contained a distinct nucleus and nucleolus. They were only so far acted on by acetic acid that the nucleus was thus rendered more distinct. A very small con- cretion was removed from between two of the lamellae within an anterior gland. It was embedded in pulpy cellular matter, with many free calciferous cells, together with a i8 HABITS OF WOKMS. Chap, h multitude of the larger, free, nucleated cells, aud these latter cells were not acted on by acetic acid, while the former were dissolved. From this and other such cases I am led to suspect that the calciferous cells are developed from the larger nucleated ones ; but how this is effected was not ascertained. When an anterior gland contains several minute concretions, some of these are generally angular or crystalline in outline, while the greater number are rounded with an irregu- lar mulberry-like surface. Calciferous cells adhered to many parts of these mulberry-like masses, and their gradual disappearance could be traced while they still remained attached. It was thus evident that the concretions are formed from the lime contained within the free calciferous cells. As the smaller concre- tions increase in size, they come into contact and unite, thus enclosing the now functionless lamellge ; and by such steps the formation of the largest concretions could be followed. Why the process regularly takes place in th© two anterior glands, and only rarely in the four posterior glands is quite unknown. Morren says that these glands disappear Chap. I. CALCIFEROUS GLANDS. 49 during the winter ; and I have seen some instances of this fact, and others in which either the anterior or posterior glands were at this season so shrunk and empty, ttiat they could be distinguished only with much difficulty. With respect to the function of the calci- ferous glands, it is probable that they pri- marily serve as organs of excretion, and secondarily as an aid to digestion. Worms consume many fallen leaves ; and it is known that lime goes on accumulating in leaves until they drop off the parent-plant, instead of being re-absorbed into the stem or roots, like various other organic and inorganic sub- stances.'^ The ashes of a leaf of an acacia have been known to contain as much as Y2 per cent, of lime. Worms therefore would be liable to become charged with this earth, unless there were some special means for its excretion ; and the calciferous glands are well adapted for this purpose. The worms which live in mould close over the chalk, often have their intestines filled with this substance, and their castings are almost white. * De Vries, ' Landwirth. Jahrbiicher,' 1881, p. 77. 50 HABITS OF WORMS. Chap. L Here it is evident that the supply of cal- careous matter must be superabundant, Nevertheless with several worms collected on such a site, the calciferous glands contained as many free calciferous cells, and fully as many and large concretions, as did the glands of worms which lived where there was little or no lime ; and this indicates that the lime is an excretion, and not a secretion poured into the alimentary canal for some special purpose. On the other hand, the following considera- tions render it highly probable that the carbonate of lime, which is excreted by the glands, aids the digestive process under ordinary circumstances. Leaves during their decay generate an abundance of various kinds of acids, which have been grouped together under the term of humus acids. We shall have to recur to this subject in our fifth chapter, and I need here only say that these acids act strongly on carbonate of lime. The half-decayed leaves which are swallowed in such large quantities by worms would, there- fore, after they have been moistened and triturated in the alimentary canal, be apt to Chap. I. CALCIFEROUS GLANDS. 5i produce such acids. And in the case of several worms, the contents of the alimentary canal were found to be plainly acid, as shown by litmus paper. This acidity cannot be attributed to the nature of the digestive fluid, for pancreatic fluid is alkaline ; and we have seen that the secretion which is poured out of the mouths of worms for the sake of pre- paring the leaves for consumption, is likewise alkaline. The acidity can hardly be due to uric acid, as the contents of the upper part of the intestine were often acid. In one case the contents of the gizzard were slightly acid, those of the upper intestines being more plainly acid. In another case the contents of the pharynx were not acid, those of tlie gizzard doubtfully so, while those of the in- testine were distinctly acid at a distance of 5 cm. below the gizzard. Even with the higher herbivorous and omnivorous animals, the contents of the large intestine are acid. " This, however, is not caused by any acid '' secretion from the mucous membrane ; the " reaction of the intestinal walls in the larger '^ as in the small intestine is alkaline. It *' must therefore arise from acid fermentations 52 HABITS OF WORMS. Chap. I. " going on in the contents themselves. . . . *' In Garni vora the contents of the coecum " are said to be alkahne, and naturally the *• amount of fermentation will depend largely " on the nature of the food."* With worms not only the contents of the intestines, but their ejected matter or the castings, are generally acid. Thirty castings from different places were tested, and with three or four exceptions were found to be acid ; and the exceptions may have been due to such castings not having been recently ejected ; for some which were at first acid, were on the following morning, after being dried and again moistened, no longer acid ; and this probably resulted from the humus acids being, as is known to be the case, easily decomposed. Five fresh castings from worms which lived in mould close over the chalk, were of a whitish colour and abounded with calcareous matter ; and these were not in the least acid. This shows how effectually carbonate of lime neutralises the intestinal acids. When worms were kept in pots filled • M. Foster, 'A Text-Book of Physiology,' 2iid edit. 1878, p 243. CuAP. I. CALCIFEEOUS GLANDS. 53 with fine ferruginous sand, it was manifest that the oxide of iron, with which the grains of silex were coated, had been dissolved and removed from them in the castings. The digestive fluid of worms resembles Id its action, as already stated, the pancreatic secretion of the higher animals ; and in these latter, " pancreatic digestion is essentially '' alkaline ; the action will not take place " unless some alkali be present ; and the ^' activity of an alkaline juice is arrested by " acidification, and hindered by neutraliza- " tion."* Therefore it seems highly probable that the innumerable calciferous cells, which are poured from the four posterior glands into the alimentary canal of worms, serve to neutralise more or less completely the acids there generated by the half-decayed leaves. We have seen that these cells are instantly dissolved by a small quantity of acetic acid, and as they do not always sufiSce to neu- tralise the contents of even the upper part of the alimentary canal, the lime is perhaps aggregated into concretions in the anterior pair of glands, in order that some may be * M. Foster, Ibid. p. 200. 54 HABITS OF WOEMS. (Jiiap. I. carried down to the posterioi parts of the intestine, where these concretions would be rolled about amongst the acid contents. Tho concretions found in the intestines and in tho castings often have a worn appearance, but whether this is due to some amount of attrition or of chemical corrosion could not be told. Claparede believes that they are formed for the sake of acting as mill-stones, and of thus aiding in the trituration of the food. They may give some aid in this way ; but I fully agree with Perrier that this must be of quite subordinate importance, seeing that the object is already attained by stones being generally present in the gizzards and intestines of worms. CHAPTER II. HABITS OF WORMS — Continued, Jidanner in whicli worms seize objects — Their power of suction — ■ The instinct of plugging up the mouths of their burrows — Stones piled over the burrows — ^The advantages thus gained — Intelligence shown by worms in their manner of plugging up their burrows — Various kinds of leaves and other objects thus used — Triangles of paper — Summary of reasons for believing that worms exhibit some intelligence — Means by which they excavate their burrows, by pushing away the earth and swal- lowing it — P^arth also swallowed for the nutritious matter which it contains — Depth to which worms burrow, and the construction of their burrows — Burrows lined with castings, and in the upper part with leaves — The lowest part paved with little stones or seeds — Manner in which the castings are ejected — The collapse of old burrows — Distribution of worms — Tower-like castings in Bengal — Gigantic castings on the Nilgiri Mountains — Castings ejected in all countries. In the pots in which worms were ke]3t, leaves were pinned down to the soil, and at night the manner in which they were seized could be observed. The worms always endeavoured to drag the leaves towards their burrows; and they tore or sucked o£P small fragments, whenever the leaves were suffi- 56 HABITS OF WOllMS. C11A.P. II ciently tender. They generally seized the thin edge of a leaf with their mouths, between the projecting upper and lower lip ; the thick and strong pharynx being at the same time, as Perrier remarks, pushed forward within their bodies, so as to afford a point of resistance for the upper lip. In the case of broad flat objects they acted in a wholly different manner. The pointed anterior extremity of the bod}^, after being brought into contact with an object of this kind, was drawn within the adjoining rings, so that it appeared truncated and became as thick as the rest of the body. This part could then be seen to swell a little ; and this, I believe, is due to the pharynx being pushed a little forwards. Then by a sliglit withdrawal ol the pharynx or by its expansion, a vacuum was produced beneath the truncated slimy end of the body whilst in contact with the object ; and by this means the two adhered fiiinly together.* That under these circum- Btances a vacuum was produced was plainly * Claparedc remarks (' Zeitschrift fiir wissenschaft. Zoolog. B. 19, 1869, p. 602) that the pharynx appears from its structuie to be adapted for suction. Ciup. II. THEIR MANNEE OF PEEHENSION. 57 seen on one occasion, wlien a large worm lying beneath a flaccid cabbage leaf tried to drag it away ; for the surface of the leaf directly over the end of the worm's body became deeply pitted. On another occasion a worm suddenly lost its hold on a flat leaf; and the anterior end of the body was momen- tarily seen to be cup-formed. Worms can attach themselves to an object beneath watei in the same manner ; and I saw one thus dragging away a submerged slice of an onion-bulb. The edges of fresh or nearly fresh leaves affixed to the ground were often nibbled by the worms ; and sometimes the epidermis and all the parenchyma on one side was gnawed completely away over a considerable space ; the epidermis alone on the opposite side being left quite clean. The veins were never touched, and leaves were thus some- times partly converted into skeletons. As worms have no teeth and as their mouths consist of very soft tissue, it may be pre- sumed that they consume by means of suction the edges and the parenchyma of fresh leaves, after they have been softened by the 58 HABITS OF WORMS. Chap. IL digestive fluid. They cannot attack such sirong leaves as those of sea-kale or large and thick leaves of ivy ; though one of the latter after it had hecome rotten was reduced in parts to the state of a skeleton. Worms seize leaves and other objects, not only to serve as food, but for plugging up the mouths of their burrows ; and this is one of their strongest instincts. Leaves and petioles of many kinds, some flower-pedun- cles, often decayed twigs of trees, bits of paper, feathers, tufts of wool and horse-hairs are dragged into their burrows for this pur- pose. I have seen as many as seventeen petioles of a Clematis projecting from the mouth of one burrow, and ten from the mouth of another. Some of these objects, such as the petioles just named, feathers, &c,, are never gnawed by worms. In a gravel walk in my garden I found many hundred leaves of a pine-tree (P. austriaca or nigin- cans) drawn by their bases into burrows. The surfaces by which these leaves are articu- lated to the branches are shaped in as pecu- liar a manner as is the joint between the leg- bones of a quadruped ; and if these surfaces Chap. II. PROTECTION OF THEIR BURROWS. 59 had been in the least gnawed, the fact would have been immediately visible, but there was no trace of gnawing. Of ordinary dicotyle- donous leaves, all those which are dragged into burrows are not gnawed. I have seen as many as nine leaves of the lime-tree drawn into the same burrow, and not nearly all of them had been gnawed ; but such leaves may serve as a store for future con- sumption. Where fallen leaves are abun- dant, many more are sometimes collected over the mouth of a burrow than can be used, so that a small pile of unused leaves is left like a roof over those which have been partly dragged in. A leaf in being dragged a little way into a cylindrical burrow is necessarily much folded or crumpled. When another leaf is drawn in, this is done exteriorly to the first one, and so on with the succeeding leaves ; and finally all become closely folded and pressed together. Sometimes the worm enlarges the mouth of its burrow, or makes a fresh one close by, so as to draw in a still larger number of leaves. They often or generally fill up the interstices betw^een the drawn-in leaves with 60 HABITS OF WORMS. Chap. IL moist viscid earth ejected from their bodies, and thus the mouths of the burrows are securely plugged. Hundreds of such plugged burrows may be seen in many places, especially during the autumnal and early winter months. But, as will hereafter be shown, leaves are dragged into the burrows not only for plugging them up and for food, but for the sake of lining the upper part or mouth. When worms cannot obtain leaves, petioles, sticks, &c., with which to plug up the mouths of their burrows, they often protect them by little heaps of stones; and such heaps of smooth rounded pebbles may frequently be seen on gravel- walks. Here there can be no question about food. A lady, who was in- terested in the habits of worms, removed the little heaps of stones from the mouths of several burrows and cleared the surface of the ground for some inches all round. She went out on the following night with a lantern, and saw the worms with their tails fixed in their burrows^ dragging the stones inwards by the aid of their mouths, no doubt by suction. ^' After .two nights some of the Chap. IL PROTECIION OF THEIR BURROWS. 61 " holes liad 8 or 9 small stones over "them; after four nights one had about ^' 30, and another 34 stones."* One stone which had been dragged over the gravel-walk to the mouth of a burrow weighed two oances ; and this proves how strong worms are. But they show greater strength in some- times displacing stones in a well-trodden gravel-walk ; that they do so, may be inferred from the cavities left by the displaced stones being exactly filled by those lying over the mouths of adjoining burrows, as I have my- self observed. Work of this kind is usually performed during the night ; but I have occasionally known objects to be drawn into the burrows during the day. What advantage the worms derive from plugging up the mouths of their burrows with leaves, &c., or from piling stones over them, is donbtful. They do not act in this manner at the times when they eject much earth from their burrows ; for their castings then serve to cover the moutli. When gardeners wish to kill worms on a • An account of her observations is given in the ' Gardeners Chronicle,' March 28th, 1868, p. 324. 62 HABITS OF WORMS. Chap. II lawn, it is necessary first to brush or rake away the castings from the surface, in order that the h'me-water may enter the burrows.* It might be inferred from this fact that the mouths are plugged up with leaves, &c., to prevent the entrance of water during heavy rain ; but it may be urged against this view that a few, loose, well-rounded stones are ill- adapted to keep out water. I have moreover seen many burrows in the perpendicularly cut turf-edgings to gravel-walks, into which water could hardly flow, as well plugged as burrows on a level surface. Can the plugs or piles of stones aid in concealing tbe bur- rows from scolopenders, which^ according to Hoffmeister, f are the bitterest enemies of worms ? Or may not worms when thus pro- tected be able to remain with safety with their heads close to the mouths of their bur- rows, which we know that they like to do, but which costs so many of them their lives? Or may not the plugs check the free ingress, of the lowest stratum of air, when chilled by * London's ' Gard. Mag.' xvii. p. 216, as quoted in the ' Cata* logue of the British Museum Worms,' 1865, p. 327. t ' Familie der Regenwiirmer,' p. 19. CSAP. 11. PEOTECTION OF THEIK BURKOWS. 63 radiation at niglit, from the surrounding ground and herbage. I am inclined to be- lieve in this latter view ; firstly, because when worms were kept in pots in a room with a fire, in which case cold air could not enter the burrows, they plugged them up in a slovenly manner ; and secondarily, because they often coat the upper part of their burrows with leaves, apparently to prevent their bodies from coming into close contact with the cold damp earth. But the phigging-up process may perhaps serve for all the above purposes. Whatever the motive may be, it appears that worms much dislike leaving the mouths of their burrows open. Nevertheless they will reopen them at night, whether or not they can afterwards close them. Numerous open burrows may be seen on recently-dug ground, for in this case the worms eject their castings in cavities left in the ground, or in the old burrows, instead of piling them over the mouths of their burrows, and they cannot collect objects on the surface by which the mouths might be protected. So again on a recently disinterred pavement of a Roman villa at Abinger (hereafter to be described^ 64 HABITS OF WORMS. Chap II. the worms pertinaciously opened their bur- rows almost every nighty when these had been closed by being trampled on, although they were rarely able to find a few minute stones wherewith to protect them. Intelligence shown by worms in their manner of plugging up their burrows. — If a man had to plug up a small cylindrical hole, with such objects as leaves, petioles or twigs, he would drag or push them in by their pointed ends ; but if these objects were very thin relatively to the size of the hole, he Avould probably insert some by their thicker or broader ends. The guide in his case would be intelligence. It seemed therefore worth while to observe carefully how worms dragged leaves into their burrows ; whether by their tips or bases or middle parts. It seemed more espe- cially desirable to do this in the case of plants not natives to our country ; for although the habit of dragging leaves into their burrows is undoubtedly instinctive with worms, yel instinct could not tell them how to act in the case of leaves about which their pro- genitors knew nothing. If, moreover, worms acted solely through instinct or an unvary* Chap. II. THEIR INTELLIGENCE. 65 ing inherited impulse, they would draw all kinds of leaves into their burrows in the same manner. If they have no such definite instinct, we might expect that chance would determine whether the tip, base or middle was seized. If both these alternatives are ex- cluded, intelHgence alone is left ; unless the worm in each case first tries many different methods, and follows that alone which proves possible or the most easy ; but to act in this manner and to try different methods makes a near approach to intelligence. In the first place 227 withered leaves of various kinds, mostly of English plants, were pulled out of worm-burrows in several places. Of these, 181 had been drawn into the burrows by or near their tips, so that the foot-stalk projected nearly upright from the mouth of the burrow ; 20 had been drawn in by their bases, and in tbis case the tips pro- jected from the burrows ; and 26 had been seized near the middle, so that these had been drawn in transversely and u-ere much crumpled. Therefore 80 per cent, (always using the nearest whole 'number) had been drawn in by the tip, 9 per cent, by the base B^ HABITS OF WORMS. Chap. IL or footstalk, and 11 per cent. traDSversely or by the middle. This alone is almost suffi- cient to show that chance does not determine the manner in which leaves are dragged into the burrows. Of the above 227 leaves, 70 consisted of the ftillen leaves of the common lime-tree, which is almost certainly not a native of England. These leaves are .much acumin- ated towards the tip, and are very broad at the base with a w^ell-developed foot-stalk. They are thin and quite flexible when half- withered. Of the 70, 79 per cent, had been drawn in by or near the tip ; 4 per cent by or near the base ; and 17 per cent, trans- versely or by the middle. These proportions agree very closely, as far as the tip is con- cerned, with those before given. But the per- centage drawn in by the base is smaller, which may be attributed to the breadth of the basal part of the blade. We here, also, see that the presence of a foot-stalk, which it might have been expected would have tempted the worms as a convenient handle, has little or no in- fluence in determining the manner in which iime leaves are dragged into the burrows. Chap. IL THEIR INTELIJGENCE. 67 The considerable proportioi], viz.^ 17 per cent., drawn in more or less transversely depends no doubt on the flexibility of these half-decayed leaves. The fact of so many having been drawn in by the middle, and of some few having been drawn in by the base, renders it improbable that the worms first tried to draw in most of the leaves by one or both of these methods, and that they after- wards drew in 79 per cent, by their tips; for it is clear that they would not have failed in drawing them in by the base or middle. The leaves of a foreign plant were next searched for, the blades of which were not more pointed towards the apex than towards the base. This proved to be the case with those of a laburnum (a hybrid between Cytisus alpinus and laburnum) for on doubling the terminal over the basal half, they gene- rally fitted exactly ; and when there was any difference, the basal half was a little the narrower. It might, therefore, have been expected that an almost equal number of the>e leaves would have been drawn in by the tip and base, or a slight excess in favour of the latter. But of 73 leaves (not included m t)8 HABITS OF WORMS. CnAP. IL the first lot of 227) pulled out of worm- burrows, 63 per cent, had been drawn in by the tip ; 27 per cent, by the base, and 10 per cent, transversely. We here see that a far larger proportion, viz., 27 per cent, were drawn in by the base than in the case of lime leaves, the blades of which are very broad at the base, and of which only 4 per cent, had thus been drawn in. We may perhaps account for the fact of a still larger proportion of the laburnum leaves not hav- ing been drawn in by the base, by worms having acquired the habit of generally draw ing in leaves by their tips and thus avoid- ing the foot-stalk. For the basal m.argin of the blade in many kinds of leaves forms a large angle with the foot-stalk ; and if such a leaf were drawn in by the foot-stalk, the basal margin would come abruptly into contact with the ground on each side of the burrow, and would render the drawing in of the leaf very difiicult. Nevertheless worms break through their habit of ai^oiding the footstalk, if this part offers them the most convenient means for drawing leaves into their burrows. The leaves Chai'. ri. THEIR INTELLIGENCE. 69 of the endless hybridised varieties of the Rhododendron vary much in shape ; some are narrowest towards the base and others to- wards the apex. After they have fallen off, the blade on each side of the midrib often becomes curled up while drying, sometimes along the whole length, sometimes chiefly at the base, sometimes towards the apex. Out of 28 fallen leaves on one bed of peat in my garden, no less than 23 were narrower in the basal quarter than in the terminal quarter of their length ; and this narrowness was chiefly due to the curling in of the margins. Out of 36 fallen leaves on another bed, in which different varieties of the Rhododendron grew, only 17 were narrower towards the base than towards the apex. My son William, who first called my attention to this case, picked up 237 fallen leaves in his garden (where the Rhododendron grows in the natural soil) and of these 65 per cent, could have been drawn by worms into their bur- rows more easily by the base or foot-stalk than by the tip ; and this was partly due to the shape of the leaf and in a less degree to the curling in of the margins : 27 per 70 HABITS OF WORMS. .Chap. IL cent, could have been drawn in more easily by the tip than by the base : and 8 per cent, with about equal ease by either end. The sliape of a fallen leaf ought to be judged of before one end has been drawn into a burrow, for after this has happened, the free end, whether it be the base or apex, will dry more quickly than the end embedded in the damp ground ; and the exposed margins of the free end will consequently tend to become more curled inwards than they were when the leaf was first seized by the worm. My son found 91 leaves which had been dragged by worms into their burrows, though not to a great depth ; of these 6Q per cent, had been drawn in by the base or foot-stalk ; and 34 per cent, by the tip. In this case, there- fore, the worms judged with a considerable degree of correctness how best to draw the withered leaves of this foreign plant into their burrows; notwithstanding that they had to depart from their usual habit of avoiding the foot-stalk. On the gravel-w^alks in my garden a very large number of leaves of three species of Pinus (P. austriaca, nigricars and sylvestri^) Chap. IL THEIR INTELLIGENCE. 71 are regularly drawn into the mouths of worm- burrows. These leaves consist of two needles, which are of considerable length in the two first and short in the last named species, and are united to a common base ; and it is by this part that they are almost invariably drawn into the burrows. I have seen only two or at most three exceptions to this rule with worms in a state of nature. As the sharply pointed needles diverge a little, and as several leaves are drawn into the same burrow, each tuft forms a perfect chevaux de frise. On two occasions many of these tufts were pulled up in the evening, but by the following morning fresh leaves had been pulled in, and the burrows were again well protected. These leaves could not be dragged into the burrows to any depth, except by their bases, as a worm cannot seize hold of the two needles at the same time, and if one alone were seized by the apex, the other would be pressed against the ground and would resist the entry of the seized one. This was manifest in the above mentioned two or three excep- tional cases. In order, therefore that worma should do their work well, they must drag 6 72 HABITS OF WOEMS. Chap. IL pine-leaves into their burrows by tlieir bases, where the two needles are conjoined. But how they are guided in this work is a per- plexing question. This difficulty led my son Francis and my- self to observe worms in confinement during several nights by the aid of a dim light, while they dragged the leaves of the above named pines into their burrows. They moved the anterior extremities of their bodies about the leaves, and on several occasions when they touched the sharp end of a needle they with- drew suddenly as if pricked. But I doubt whether they were hurt, for they are indif- ferent to very sharp objects, and will swallow even rose-thorns and small splinters of glass. It may also be doubted, whether the sharp ends of the needles serve to tell them that this is the wrong end to seize ; for the points were cut off many leaves for a length of about one inch, and fifty-seven of them thus treated were drawn into the burrows by their bases, and not one by the cut-off ends. The worms in confinement often seized the needles near the middle and drew them to- wards the mouths of their burrows ; and one CiiAP. II. THEIR INTELLIGENCE. 73 worm tried in a senseless manner to drag tliem into the burrow by bending tbem. They sometimes collected many more leaves over the mouths of their burrows (as in the case formerly mentioned of lime-leaves) than could enter them. On other occasions, how- ever, they behaved very differently ; for as soon as they touched the base of a pine-leaf, this was seized, being sometimes completely en- gulfed in their months, or a point very near the base was se^'zed, and the leaf was then quickly dragged or rather jerked into their burrows. It appeared both to my son and myself as if the worms instantly perceived as soon as they had seized a leaf in the proper manner. Nine such cases were observed, but in one of them the worm failed to drag the leaf into its burrow, as it was entangled by other leaves lying near. In another case H leaf stood nearly upright with the points of the needles partly inserted into a burrow, but how placed there was not seen ; and then the n«i«tincr nf two needles arising from, a com- mon base 100 Chap. II. THEIR INTELIJGENCE. 91 Nature of Object. Drawn into the burrows, by or near the Drawn in, by or: near the middle. apex. 76 48-5 •• 44 62 15 59 ■ 25 65 14 Drawn in, by ct near the base. Petioles of a Clematis, somewhat pointed at the apex, and blimt at the base of the Ash, the thick basal end often drawn in to serve as food .... of Robinia, extremely thin, especially towards the apex, so as to be ill-fitted fur plugging up the burrows . Triangles of paper, of the two sizes . of the broad ones alone • of the narrow ones alone 24 51-5 56 23 16 21 If we consider these several cases, we can Lardly escape from the conclusion that worms show some degree of intelligence in their manner of plugging up their burrows. Each particular object is seized in too uniform a manner, and from causes which we can generally understand, for the result to be attributed to mere chance. That every object has not been drawn in by its pointed end, may be accounted for by labour having been saved through some being inserted by their broader or thicker ends. No doubt worms 92 HABITS OF WOKMS. Chap. II are led by instinct to plug up their burrows ; and it might have been expected that they would have been led by instinct how best- to act in each particular case, independently of intelligence. We see how difficult it is to judge whether intelligence comes into play, for even plants might sometimes be thought to be thus directed ; for instance when dis- placed leaves re-direct their upper surfaces towards the light b}^ extremely complicated movements and by the shortest course. With animals, actions appearing due to intelligence may be performed through inherited habit without any intelligence, although aborigin- ally thus acquired. Or the habit may have been acquired through the preservation and inheritance of beneficial variations of some other habit ; and in this case the new habit will have been acquired independently of intelligence throughout the whole course of its development. There is no a prion improbability in worms having acquired special instincts through either of these two latter means. Nevertheless it is incredible that instincts should have been developed in reference to objects, such as the leaves or Chap. II. THEIR INTELLIGENCE. 93 petioles of foreign plants, wholly unknown to the progenitors of the worms which act in the described manner. Nor are their actions 80 unvarying or inevitable as are most true instincts. As worms are not guided by special in- stincts in each particular case, though pos- sessing a general instinct to plug up their burrows, and as chance is excluded, the next most probable conclusion seems to be that they try in many different ways to draw in objects, and at last succeed in some one way. But it is surprising that an animal so low in the scale as a worm should have the capacity for acting in this manner, as many higher animals have no such capacity. For instance, ants may be seen vainly trying to drag an object transversely to their course, which could be easily drawn lougi- fcudinally ; though after a time they gener- ally act in a wiser mauner. M. Fabre states* that a Sphex — an insect belong- ing to the same highly-endowed order with ants — stocks its nest with paralysed * See his interesting work, ' Souvenirs entomologiques,' 1879, pp. 168-177. 9i HABITS OF WORMS. Chap. IL grasshoppers, which are invariably dragged into the burrow by their antennae. When these were cut off close to the head, the Sphex seized the palpi ; but when the.se were likewise cut off, the attempt to drag its prey into the burrow was given up in despair. The Sphex had not intelHgence enough to seize one of the six legs or the ovipositor of the grasshopper, which, as M. Fabre remarks, would have served equally well. So again, if the paralysed prey with an egg attached to it be taken out of the cell, the Sphex after entering and finding the cell empty, nevertheless closes it up in the usual elaborate manner. Bees will try to escape and go on buzzing for hours on a window, one half of which has been left open. Even a pike continued during three months to dash and bruise itself against the glass sides of an aquarium, in the vain attempt to seize minnows on the opposite side.* A cobra- snake was seen by Mr. Layard f to act much more wisely than either the pike or the Sphex ; * Mobius, 'Die Bewegiingen der Thiere,' &c., 1873, p. 111. t 'Annals and Mag. of N. Uistory,' series ii. vol. ix. 1852, P. 333. CiiAP. II. THEIR INTELLIGENCE. 95 it had swallowed a toad lying w^ithin a hole, and could not withdraw its head ; the toad was disgorged, and hegan to crawd away; it was again swallowed and again disgorged ; and now the snake had learnt by experience, for it seized the toad by one of its legs and drew^ it out of the hole. The instincts of even the higher animals are often followed in a senseless or purposeless manner : the weaver-bird will perseveringly wind threads through the bars of its cage, as if building a nest : a squirrel will pat nuts on a wooden floor, as if he had just buried them in the ground : a beaver will cut up logs of wood and drag them about, though there is no water to dam up ; and so in many other cases. Mr, Romanes who has specially studied the minds of animals, believes that we can safely infer intelligence, only when we see an individual profiting by its own experience. By this test the cobra showed some intelli- gence ; but this would have been much plainer if on a second occasion he had drawn a toad out of a hole by its leg. The Sphex failed signally in this respect. Now if worms try to drag objects into their burrows 96 HABITS OF "WORMS. Chap. II. first in one way and then in another, until they at last succeed, they profit, at least in each particular instance, by experience. But evidence has been advanced showing t]iat worms do not habitually try to draw objects into their burrows in many difierent ways. Thus half-decayed lime-leaves from their flexibility could have been drawn in by their middle or basal parts, and were thus drawn into the burrows in considerable numbers; yet a large majority were drawn in by or near the apex. The petioles of the Clematis could certainly have been drawn in with equal ease by the base and apex ; yet three times and in certain cases five times as many were drawn in by the apex as by the base. It might have been thought that the foot-stalks of leaves would have tempted the worms as a convenient handle ; yet they are not largely used, except when the base of the blade is narrov/er than the apex. A large number of the petioles of the ash are drawn in by the base ; tut this part serves the worms as food. In the case of pine-leaves worms plainly show that they at least do not seize the leaf by chance ; but their CnAP. II. THEIR INTELLIGENCE. 97 choice does not appear to be determined by the divergence of the two needles, and the consequent advantage or necessity of drawing them into their burrows by the base. With respect to the triangles of paper, those which had been drawn in by the apex rarely had their bases creased or dirty ; and this shows that the worms had not often first tried to drag them in by this end. If worms are able to judge, either before drawing or after having drawn an object close to the mouths of their burrows, how best to drag it in, they must acquire some notion of its general shape. This they pro- bably acquire by touching it in many places with the anterior extremity of their bodies, which serves as a tactile organ. It may be well to remember how perfect the sense of touch becomes in a man when born blind and deaf, as are worms. If worms have the power of acquiring some notion, however rude, of the shape of an object and of their burrows, as seems to be the case, they deserve to be called intelligent ; for they then act in nearly the same manner as would a man under similar circumstances. 98 HABITS OF vVORMS. Cuap. II To sum up, as chance does not determine the manner in which objects are drawn into the burrows, and as the existence of special- ized instincts for each particular case cannot be admitted, the first and most natural sup- position is that worms try all methods until they at last succeed ; but many appearances are opposed to such a supposition. One alternative alone is left, namely, that worms, although standing low in the scale of organiz- ation, possess some degree of intelligence. This will strike every one as very impro- bable ; but it may be doubted whether we know enough about the nervous system of the lower animals to justify our natural dis- trust of such a conclusion. With respect to tlie small size of the cerebral ganglia, we should remember ' what a mass of inherited knowledge, with some power of adapting means to an end, is crowded into the minute brain of a worker-ant. Means by which worms excavate their burrows. — This is effected in two ways ; by pushing away the earth on all sides, and by swallowing it. In the former ca^e, the worm inserts the stretched out and attenuated Chap. II. EXCAVATION OF THEIE BUEEOWS. 99 anterior extremity of its body into any little crevice, or hole ; and then, as Perrier re> marks,* the pharynx is pushed forwards iiito this part, which consequently swells and pushes away the earth on all sides. The anterior extremity thus serves as a wedge. It also serves, as we have before seen, for prehension and suction, and as a tactile organ. A worm was placed on loose mould, and it buried itself in between two and three minutes. On another occasion four worms disappeared in 15 minutes between the sides of the pot and the earth, which had been moderately pressed dowu. On a third oc- casion three large worms and a small one were placed on loose mould well mixed with fine sand and firmly pressed down, and they all disappeared, except the tail of one, in 35 minutes. On a fourth occasion six large worms were placed on argillaceous mud mixed with sand firmly pressed down, and they disappeared, except the extreme tips of the tails of two of them, in 40 minutes. In none of these cases, did the worms swallow, as far as could be seen, any earth. They * ' Archives de Zoolog exper.' torn. iii. 1874, p. 405. 100 HABITS OF WORMS. Chap. IL generally entered the ground close to tlie sides of the pot. A pot was next filled with very fine ferru- ginous sand, whicli was pressed down, well watered, and thus rendered extremely com- pact. A large worm left on the surface did not succeed in penetrating it for some hours, and did not bury itself completely until 25 hrs. 40 min. had elapsed. This was effected by the sand being swallowed, as was evident by the large quantity ejected from the vent, long before the whole body had disappeared. Castings of a similar nature continued to be ejected from the burrow during the whole of the following day. As doubts have been expressed by some writers whether worms ever swallow earth solely for the sake of making their burrows, some additional cases may be given. A mas? of fine reddish sand, 23 inches in thickness, left on the ground for nearly two years, had been penetrated in many places by worms ; and their castings consisted partly ot the reddish sand and partly of black earth brought up from beneath the mass. This sand had been dug up from a considerable Ch.ap. TI. excavation OF THEIR BUEEOWS. 101 depth, and was of so poor a nature that weeds could not grow on it. It is therefore highly improbable that it should have been swallowed by the worms as food. Again ia a field near my liouse the castings frequently consist of almost pure chalk, which lies at only a little depth beneath the surface ; and here again it is very improbable that the chalk should have been swallowed for the sake of the very little organic matter which could have percolated into it from the poor over- lying pasture. Lastly, a casting thrown up through the concrete and decayed mortar between the tiles, with which the now ruined aisle of Beaulieu Abbey had formerly been paved, was washed, so that the coarser matter alone was left. This consisted of grains of quartz, micaceous slate, other rocks, and bricks or tiles, many of them from -^^ to ■jL inch in diameter. No one will suppose that these grains were swallowed as food, yet they formed more than half of the casting, for they weighed 19 grains, the whole cast- ing having weighed 33 grains. Whenever a worm burrows to a depth of some feet in undisturbed compact ground, it must form its L02 HABITS OF WOllMS. Chap. U passage by swallowing the earth ; for it is incredible that the ground could yield on all sides to the pressure of the pharynx when pushed forwards within the worm's body. That worms swallow a larger quantity of earth for the sake of extracting any nutritious matter which it may contain than for making their burrows, appears to me certain. But as this old belief has been doubted by so high an authority as Claparede, evidence in its favour must be given in some detail. There is no a priori improbability in such a belief, for besides other annelids, especially the Arenicola marina, which throws up such a profusion of castings on our tidal sands, and which it is believed thus subsists, tliere ;ire animals belonging to the most distinct classes, which do not burrow, but habitually swallow large quantities of sand ; namely the mollus- can Oncliidium and many Echinoderms.* If earth were swallowed only when worms deepened their burrow^s or made new ones, castings would be thrown up only occasion- ally ; but in many places fresh castings may * I state this on the authority of Semper, 'Eeisen im Archii>l der rhilippinen," Th. ii. 1877, p. 30. Chap. IT. EARTH SWALLOWED AS FOOD. 103 be seen every morning, and the amount of earth ejected from the same burrow on successive days is large. Yet worms do not burrow to a great depth, except when tlie weather is very dry or intensely cold. On my lawn the black vegetable mould is only about 5 inches in thickness, and overlies light- coloured or reddish clayey soil: now when castings are thrown up in the greatest profusion, only a small proportion are light coloured, and it is incredible that the worms should daily make fresh burrows in every direction in the thin superficial layer of dark -coloured humus, unless they obtained nutriment of some kind from it. I have observed a strictly analogous case in a field near my house where bright red clay lay close beneath the surface. Again on one part of the Downs near Winchester the vegetable mould overlying the chalk was found to be only from 3 to 4 inches in thickness ; and the many castings here ejected were as black as ink and did not effervesce with acids ; so that the worms must have confined themselves to this thin superficial layer of mould, of which large quantities were daily swallowed. In i04 HABITS OF WORMS. Cuap. II. another place at no great distance the castings were white ; and why the worms should have burrowed into the chalk in some places and not in others, I am unable to conjecture. Two great piles of leaves had been left to decay in my grounds, and months after their removal, the bare surface, several yards in diameter, was so thickly covered during several months with castings that they formed an almost continuous layer ; and the large number of worms which lived here must have subsisted during these months on nutritious matter contained in the black earth. The lowest layer from another pile of de- cayed leaves mixed with some earth was ex- amined under a high power, and the number of spores of various shapes and sizes which it contained was astonishingly great ; and these crushed in the gizzards of worms may largely aid in supporting them. When- ever castings are thrown up in the greatest number, few or no leaves are drawn into the burrows ; for instance the turf along a hedge- row, about 200 yards in length, was daily observed in the autumn during several weeks, Chap. II. EARTH SWALLOWED AS FOOD. 105 and every morning many fresli castings were seen ; but not a single leaf was drawn into these burrows. These castings from their blackness and from the nature of the subsoil could not have been brought up from a greater depth than 6 or 8 inches. On what could these worms have subsisted during this whole time, if not on matter contained in the black earth ? On the other hand, whenever a large number of leaves are drawn into the burrows, the worms seem to subsist chiefly on them, for few earth-castings are then ejected on the surface. This difference in the behaviour of worms at different times, perhaps explains a statement by Claparede, namely, that triturated leaves and earth are always found in distinct parts of their intestines. Worms sometimes abound in places where they can rarely or never obtain dead or living leaves ; for instance, beneath the pave- ment in well-swept courtyards, into which leaves are only occasionally blown. My son Horace examined a house, one corner of which had subsided; and he found here in the cellar, which was extremely damp, many small worm-castings thrown up between the 106 HABITS OF WORMS. Chap. IL stones witli which the cellar was paved ; and in this case it is improbable that the worms could ever have obtained leaves. But the best evidence, known to me, of worms subsisting for at least considerable periods of time solely on the organic matter contained in earth, is afforded by some facts communicated to me by Dr. King. Near Nice large castings abound in extraordinary numbers, so that 5 or 6 were often found within the space of a square foot. They consist of fine, pale-coloured earth, containing calcareous matter, which after having passed through the bodies of worms and being dried, coheres with considerable force. I have reason to believe that these castings had been formed by species of Perichaata, which have been naturalised here from the East.* Thev * Dr. King gave me some worms collected near Nice, whicli, as he "believes, had constructed these castings. They were sent to M. Perrier, who with great kindness examiaed and named them for me: they consisted of Ferichceta affinis, a native of Cochin China and of the Philippines ; P. Luzonica, a native of Luzon in the Philippines ; and P. HouUeti, which lives near Calciitta. M. Perrier informs me that species of Perichaata have been natural- ized in the gardens near Montpellier and in Algiers. Before I had any reason to suspect that the tower-like castings from Nice had been formed by worm? not endemic in the country, I waa Chap. II. EAETH SWALLOWED AS FOOD. 107 rise like towers (see Fig. 2), with their sum- inits often a httle hroader than their bases, Fig. 2. Towfer-Iike casting from near Nice, constructed of earth, voided prooably by a species of Pericliseta : of natural size, copied from a photograph. sometimes to a height of above 3 and often to a height of 2 J inches. The tallest of those greatly surprised to see how closely they resembled castings sent to me from near Calcutta, where it is known that species of Perich£eta abound. 108 HABITS OF WORMS. Chap. II. whicli were measured was 3*3 inch in height and 1 in diameter. A small cylindrical pas- sage runs up the centre of each tower, through which the worm ascends to eject the earth which it has swallowed, and thus to add to its height. A. structure of this kind would not allow leaves being easily dragged from the surrounding ground into the bur- rows ; and Dr. King, who looked carefully, never saw even a fragment of a leaf thus drawn in. Nor could any trace be discovered of the worms having crawled down the ex- terior surfaces of the towers in search of leaves; and had they done so, tracks would almost certainly have been left on the upper part whilst it remained soft. It does not, however, follow that these worms do not draw leaves into their burrows during some other season of the year, at which time they would not build up their towers. From the several foregoing cases, it can hardly be doubted that worms swallow earth, not only for the sake of making their bur- rows, but for obtaining food. Hensen, how- ever, concludes from his analyses of humus that worms probably could not live on Chap. U. DEPTH OF THEIK BURROWS. 109 ordinary vegetable mould, though he admits that they might be nourished to some extent by leaf-mould.* But we have seen that worms eagerly devour raw meat, fat, and dead worms ; and ordinary mould can hardly fail to contain many ova^ larvae, and small living or dead creatures, spores of crypto- gamic plants, and micrococci, such as those which give rise to saltpetre. These various organisms, together with some cellulose from any leaves and roots not utterly decayed, might well account for such large quantities of mould being swallowed by worms. It may be worth while here to recall the fact that certain species of Utricularia, which grow in damp places in the tropics, possess bladders beautifully constructed for catching minute subterranean animals ; and these traps would not have been developed unless many small animals inhabited such soil. The depth to which worms penetrate^ and the construction of their burrows. — Although worms usually live near the surface, yet they burrow to a considerable depth during long- * * Zeitsclirift fiii- wissenscliaft. Zoolog.' B. xxviii. 1877 p. 3G4. 110 HABITS OF WOEMS. Chap. II. continued dry weather and severe cold. In Scandinavia, according to Eisen, and in Scot- land, according to Mr. Lindsay Carnagie, the burrows run down to a depth of from 7 to 8 feet ; in North Germany, according to Hoff- meister, from 6 to 8 feet, but Hensen says, from 3 to 6 feet. This latter observer has seen worms frozen at a depth of 1^ feet beneath the surface. I have not myself had many opportunities for observation, but I have often met v/ith worms at depths of 3 to 4 feet. In a bed of fine sand overlying the chalk, which had never been disturbed, a worm was cut into two at 55 inches, and another was found here in December at the bottom of its burrow, at 61 inches beneath the surface. Lastly, in earth near an old Eoman Yilla, which had not been disturbed for many centuries, a worm w^as met with at a depth of 66 inches ; and this was in the middle of August. The burrows run down perjoendicularly, or more commonly a little obhquely. They are said sometimes to branch, but as far as I have seen this does not occur, except in recently dug ground and near the surface. They are Chap. II. CONSTRUCTION OF THEIR BURROWS. Ill generally, or as I believe invariably, lined with a thin layer of fine, dark-coloured earth voided by the worms ; so that they must dt first be made a little wider than their ultimate diameter. I have seen several burrows in undisturbed sand thus lined at a depth of 4 ft. 6 in. ; and others close to the surface thus lined in recently dug ground. The walls of fresh burrows are often dotted with httle globular pellets of voided earth, still soft and viscid ; and these, as it appears, are spread out on all sides by the worm as it travels up or down its burrow. The lining thus formed becomes very com pact and smooth when nearly dry, and closely fits the worm's body. The minute reflexed bristles which project in rows on all sides from the body, thus have excellent points of support ; and the burrow is rendered w^ell adapted for the rapid movement of the animal. The lining appears also to strengthen the walls, and perhaps saves the worm's body from being scratched. I think so because several burrows which passed through a layer of sifted coal-cinders, spread over turf to a thickness of 1^ inch, had been thus lined to an 112 HABITS OF WORMS. Chap. II unusual thickness. In tliis case the worms, judging from the castings, had pushed the cinders away on all sides and had not swallowed any of them. In another place, burrows similarly lined, passed through a layer of coarse coal-cinders, 3^ inches in thickness. We thus see that the burrows are not mere excavations, but may rather be compared with tunnels lined with cement. The mouths of the burrow are in addition often lined with leaves ; and this is an instinct distinct from that of plugging them up, and does not appear to have been hitherto noticed. Many leaves of the Scotch-fir or pine {Pinus sylvestris) were given to worms kept in con- finement in two pots ; and when after several weeks the earth was carefully broken up, the upper parts of three oblique burrows were found surrounded for lengths of 7, 4, and 3^ inches with pine-leaves, together with fragments of other leaves which had been given the worms as food. Glass beads and bits of tile, which had been strewed on the surface of the soil, were stuck into the inter- stices between the pine-leaves ; and these interstices were likewise plastered with the Chap. II. CONSTEUCTION OF THEIR BUEROWS. 113 viscid castings voided by the worms. The structures thus formed cohered so well, that I succeeded in removing one with only a little earth adhering to it. It consisted of a sli ghtly curved cylindrical case, the interior of which could be seen through holes in the sides and at either end. The pine-leaves had all been drawn in by their bases; and the sharp points of the needles had been pressed into the lining of voided earth. Had this not been effectually done, the sharp points would have prevented the retreat of the worms into Their burrows ; and these structures would have resembled traps armed with converging points of wire, rendering the ingress of an animal easy and its egress difiScult or im- possible. The skill shown by these worms is noteworthy and is the more remarkable, as the Scotch pine is not a native of this district After having examined these burrows made by worms in confinement, I looked at those in a flower-bed near some Scotch pines. These had all been plugged up in the ordinary manner with the leaves of this tree, drawn in for a length of from 1 to 1| inch; but the mouths of many of them were likewise lined L14 HABITS OF WOEMS. Chap. 11 with tliem, mingled with fragments of other kinds of leaves, drawn in to a depth of 4 or 5 inches. Worms often remain, as formeilj stated^ for a long time close to the mouthg of their burrows, apparently for warmth ; and the basket-like structures formed of leaves w^ould keep their bodies from coming into close contact with the cold damp earth. That they habitually rested on the pine-leaves, was rendered probable by their clean and almost polished surfaces. The burrows which run far down into the ground, generally, or at least often, terminate in a little enlargement or chamber. Here, ac- cording to Hoffmeister, one or several worms pass the winter rolled up into a ball. Mr. Lindsay Carnagie informed me (1838) that he had examined many burrows over a stone- quarry in Scotland, where the overlying boulder-clay and mould had recently been cleared away, and a little vertical cliff thus left. In several cases the same burrow was a little enlarged at two or three points one beneath the other ; and all the burrows ter- minated in a rather large chamber, at a depth of 7 or 8 feet from the surface. These cham- Chap. II. CONSTRUCTION OF THEIR BURROWS. 115 bers contained many small sharp bits of ston^ and husks of flax-seeds. They must also have contained living seeds, for on the follow- ing spring Mr. Carnagie saw grass-plants sprouting out of some of the intersected chambers. I found at Abinger in Surrey two burrows terminating in similar chambers at a depth of 36 and 41 inches, and these were lined or paved with little pebbles, about as large as mustard seeds ; and in one of the chambers there was a decayed oat-grain, with its husk. Hensen likewise states that the bottoms of the burrows are lined with little stones ; and where these could not be procured, seeds, apparently of the pear, had been used, as many as fifteen having been carried down into a single burrow, one of which had germinated.* We thus see how easily a botanist might be deceived who wished to learn how long deeply buried seeds remained alive, if he were to collect earth from a considerable depth, on the supposition tliat it could contain only seeds which had long lain buried. It is probable that the little stones, * ' Zeitsclirift fiir wissenschaft. Zoolosr.' B. xxviii. 1877, p. 350, 116 HABITS OF WOKMS. Chap. II. as well as the seeds, are carried down from the surface by being swallowed ; for a sur- prising number of glass beads, bits of tile and of glass were certainly thus carried down by worms kept in pots ; but some may have been carried down within their mouths. The sole conjecture which I can form why worms line their winter- quarters with little stones and seeds, is to prevent their closely coiled-up bodies from coming into close contact with the surrounding cold soil ; and such contact would perhaps interfere with their respiration which is effected by the skin alone. A worm after swallowing earth, whether for making its burrow or for food, soon comes to the surface to empty its body. The ejected earth is thoroughly mingled with the intestinal secretions, and is thus rendered viscid. After being dried it sets hard. I have watched worms during the act of ejection^ and when the earth was in a very liquid state it was ejected in little spurts, and when not so liquid by a slow peristaltic movement. It is not cast indifferently on any side, but with some care, first on one and then on another feide ; the tail being used almost like a troweb Chap. II. EJECTION OF THEIR CASTINGS. 117 As soon as a little heap is formed, the worm apparently avoids, for the sake of safety, protruding its tail ; and the earthy matter is forced up through the previously deposited soft mass. The mouth of the same burrow is used for this purpose for a consider- able time. In the case of the tower-hke castings (see Fig. 2) near Nice, and of the similar but still taller towers from Bengal (hereafter to be described and figured) a considerable degree of skill is exhibited in their construction. Dr. King also observed that the passage up these towers hardly ever ran in the same exact line with the under- lying burrow, so that a thin cylindrical object such as a haulm of grass, could not be passed down the tower into the burrow ; and this change of direction probably serves in some manner as a protection. When a worm comes to the surface to eject earth, the tail protrudes, but when it collects leaves its head must protrude. Worms therefore must have the power of turning round in their closely- fitting burrows ; and this, as it appears to us, would be a difficult feat. Worms do not always eject their castings on 118 HABITS OF WORMS. Chap. II. the surface of the ground. When they can find any cavity, aKS when burrowing in newly turned-up earth, or between the stems of banked-up plants, they deposit their castings in such places. So again any hollow beneath a large stone lying on the surface of the ground, is soon filled up with their castings. According to Hensen, old burrows are habitu- ally used for this purpose ; but as far as my experience serves, this is not the case, except- ing with those near the surface in recently dug ground. I think that Hensen may have been deceived by the walls of old burrows, lined with black earth, having sunk in or collapsed ; for black streaks are thus left, and these are conspicuous when passing through light- coloured soil, and might be mistaken for completely filled-up burrows. It is certain that old burrows collapse in the course of time ; for as we shall see in the next chapter, the fine earth voided by worms, if spread out uniformly, would form in many })]aces in the course of a year a layer -^ of an inch in thickness; so that at any rate this large amount is not deposited within the old unused burrows. If the burrows did not collapse^ CuAP. 11. THE COLLAPSE OF OLD BURROWS. 119 the whole ground would be first thickly riddled with holes to a depth of about tea inches, and in fifty years a hollow unsu}> ported space, ten inches in depth, would be left. The holes left by the decay of succes- sively formed roots of trees and plants must likewise collapse in the course of time. The burrows of worms run down perpen- dicularly or a little obliquely, and where the soil is at all argillaceous, there is no difficulty in believing that the walls would slowly flow or slide inwards during very wet weather. When, however, the soil is sandy or mingled with many small stones, it can hardly be viscous enough to flow inwards during even the wettest weather; but another agency may here come into play. After much rain the ground swells, and as it cannot expand latei-ally, the surface rises ; durmg dry weather it sinks again. For instance, a large flat stone laid on the surface of a field sank 3*33 mm. whilst the weather was dry between May 9th and June 13th, and rose 1'91 mm. between September 7th and 19th, much rain having fallen during the latter part of this time. During frosts and thaws 120 HABITS OF WOEMS. Guap. II. the movements were twice as great. These observations were made by my son Horace, who will hereafter publish an acco^mt of the movements of this stone during successive wet and dry seasons, and of the effects of its being undermined by worms. Now when the ground swells, if it be penetrated by cylindrical holes, such as worm-burrows, their walls will tend to yield and be pressed inwards ; and the yielding will be greater in the deeper parts (supposing the whole to be equally moistened) from the greater weight of the superincumbent soil which has to be raised, than in the parts near the sur- face. When the ground dries, the walls will shrink a little and the burrows will be a litl le enlarged. Their enlargement, however, thiough the lateral contraction of the ground, will not be favoured, but rather op- posed, by the weight of the superincumbent soil. Distribution of Worms. — Earth-worms are found in all parts of the world, and some of the genera have an enormous range.* They inhabit the most isolated islands ; they • Perrier, ' Archives de Zoolog. exp^r.' torn. 3, p. 378, 1874. Chap. 11. THEIR WIDE DISTllIBUTJON. 121 abound in Iceland, and are known to exist in the West Indies, St. Helena, Madagascar, New Caledonia and Tahiti. In the Antarctic regions, worms from Kerguelen Land have been described by Ray Lankester; and I found them in the Falkland Islands. How they reach such isolated islands is at present quite unknown. They are easily killed by salt-water, and it does not appear probable that young worms or their egg-capsules could be carried in earth adhering to the feet or beaks of land-birds. Moreover Kerguelen Land is not now inhabited by any land-bird. In this volume we are chiefly concerned with the earth cast up by worms, and I have gleaned a few facts on this subject with respect to distant lands. Worms throw up plenty of castings in the United States. In Yenezuela, castings, probably ejected by species of Urochseta, are common in the gardens and fields, but not in the forests, as I hear from Dr. Ernst of Caracas. He collected 156 castings from the court-yard of his house, having an area of 200 square yards. They varied in bulk from half a cubic centimeter to five cubic centimeters, and were on an average 122 HABITS OF WORMS. Chap. 1.1 three cubic centimeters. They were, therefore of small size in comparison with those often found in Enghmd ; for six large castings from a field near my house averaged 16 cubic centi- meters. Several species of earth-worms are common in St. Catharina in South Brazil, and Fritz Muller informs me " that in most parts of " the forests and pasture-lands, the whole soil, '' to a depth of a quarter of a metre, looks as if it "had passed repeatedly through the intestines " of earth-worms, even where hardly any cast- " ings are to be seen on the surface." A gigantic but very rare species is found tbere, the burrows of which are sometimes even two centimeters or nearly -J of an inch in diameter, and which apparently penetrate the ground to a great depth. In the dry climate of New South Wales, I hardly expected that worms would be com- mon ; but Dr. G. Krefft of Sydney, to whom I applied, after making enquiries from gardeners and others, and from his own observations, informs me that their castings abound. He sent me some collected after heavy rain, and they consisted of little pellets, about '15 inch in diameter ; and the blackened Chap. IJ. THEIR WIDE DISTRIBUTION. 123 sandy earth of which they were formed still cohered with considerable tenacity. The late Mr. John Scott of the Botanic Gardens near Calcutta made many observa* tions for me on worms living under the hot and humid climate of Bengal. The castings abound almost everywhere, in jungles and in the open ground, to a greater degree, as he thinks, than in England. After the water has subsided from the flooded rice-fields, the whole surface very soon becomes studded with castings — a fact which much surprised Mr. Scott, as he did not know how long worms could survive beneath water. They cause much trouble in the Botanic garden, "for " some of the finest of our lawns can be kept *' in anything like order only by being almost '' daily rolled ; if left undisturbed for a few days ** they become studded with large castings." These closely resemble those described as abounding near Nice ; and they are probably fche work of , a species of Perichseta. They stand up like towers, with an open passage in the centre. A figure of one of these castings from a photograph is here given (Fig. 3). The 124 HABITS OF WOKMS. Chap. II. largest received by me was 3| inches in height and 1-35 inch in diameter; another Fig. 3. A tower-like casting, probably ejected by a species of Perichgeta, from the Botanic Garden, Calcutta : of natural size, engraved from a photograph. was only | inch in diameter and 2| in height. Cdap. II. THEIR WIDE DISTRIBUTION. 125 In the following year, Mr. Scott measured several of the largest ; one was inches in height and nearly 1^ in diameter : two others were 5 inches in height and respectively 2 and rather more than 2^ inches in diameter The average weight of the 22 castings sent to me was 35 grammes (li oz.) ; and one of them weighed 44*8 grammes (or 2 oz.). All these eastings were thrown up either in one night or in two. Where the ground in Bengal is dry, as under large trees, castings of a different kind are found in vast numbers : these con- sist of little oval or conical bodies, from about the 2V ^^ rather above -^^ of an inch in length. They are obviously voided by a distinct species of worms. The period during which worms neai Calcutta display such extraordinary activity lasts for only a little over two months namely, during the cool season after the rains. At this time they are generally found within about 10 inches beneath the surface. Dunnpearance of the field in 1842, the transfor- mation was wonderful. This was certainly the work of the worms, for though castings were not frequent for several years, yet some were thrown up month after month, and 114 AMOUNT OF EARTH Chap. Ill tljese gradually increased in numbers as tlio pasture improved. In the year 1871 a trench was dug on the above slope, and tlie blades of grass were cut off close to the roots, so that the thickness of the turf and of the vegetable mould could be measured accur- ately. The turf was rather less than half an inch, and the mould, which did not contain any stones, 2^ inches in thickness. Beneath this lay coarse clayey earth full of flints, like that in any of the neighbouring ploughed fields. This coarse earth easily fell apart from the overlying mould when a spit was lifted up. The average rate of accumulation of the mould during the whole thirty years was only '083 inch per year (i.e., nearly one inch in twelve years) ; but the rate must have been m.uch slower at first, and after- wards considerably quicker. The transformation in the appearance of this field, which had been effected beneath my eyes, was afterwards rendered the more Bt] iking, when I examined in Knole Park a dense forest of lofty beech-trees, beneath which nothing grew. Here the ground was thickly strewed with large naked stones, and CuAP. IIL BEOUGHT UP BY WOHMS. 145 worm-castings were almost wholly absent. Obscure lines and irregularities on the sur- face indicated that the land had been cul- tivated some centuries ago. It is probable that a thick wood of young beech-trees sprung up so quickly, that time enough was not allowed for worms to cover up the stones with their castings, before the site became unfitted for their existence. Anyhow the contrast between the state of the now miscalled " stony field," well stocked with worms, and the present state of the ground beneath the old beech-trees in Knole Park, where worms appeared to be absent, was striking. A narrow path running across part of my lawn was paved in 1843 with small flag- stones, set edgeways ; but worms threw up many castings and weeds grew thickly be- tween them. During several years the path was weeded and swept ; but ultimately the weeds and worms prevailed, and the gardener ceased to sweep, merely mowing off the weeds, as often as the lawn was mowed. The path soon became almost covered u]), and after several years no trace of it wais 14G AMOUNT OF EAKTH Chap, llh lef^. On removing, in 1877, the thin over* lying layer of turf, the small flag-stones, all in their proper places, were found covered by an inch of fine mould. Two recently published accounts of sub- stances strewed on the surface of pasture-land, having become buried through the action of worms, may be here noticed. The Rev. H. C. Key had a ditch cut in a field, over which coal-ashes had been spread, as it was believed, eighteen years before ; and on the clean-cut perpendicular sides of the ditch, at a depth of at least seven inches, there could be seen, for a length of 60 yards, " a distinct, very ''even, narrow line of coal-ashes, mixed with " small coal, perfectly parallel with the top- sward."* This parallelism and the length of the section gives interest to the case. Secondly, Mr. Dancer statesy that crushed bones had been thickly strewed over a field ; and " some years " afterwards " these were found " several inches ''below the surface, at a uniform depth." Worms appear to act in the same manner in New Zealand as in Europe ; for Professor J. * ' Nature,' November 1877, p. 28. ♦ * Proc. Phil. Soc' of Manchester, 1877, p. 247, Chap III. BROUGHT UP BY WORMS. 147 von Haast has described * a section near the coast, consisting of mica-schist, " covered by "5 or 6 feet of loess, above which about ] 2 " inches of vegetable soil had accumulated.'* Between the loess and the mould there was a layer from 3 to 6 inches in thickness, consisting of "cores, implements, flakes, and *' chips, all manufactured from hard basaltic "rock." It is therefore probable that the aborigines, at some former period, had left these objects on the surface, and that they had afterwards been slowly covered up by the castings of worms. Farmers in England are well aware that objects of all kinds, left on the surface of pasture-land, after a time disappear, or, as they say, work themselves downwards. How powdered lime, cinders, and heavy stones, can work down, and at the same rate, through the matted roots of a grass-covered surface, is a question which has probably never occurred to them.f • * Trans, of the New Zealand Institute,' vol. xii., 1880, p. 152. t Mr. Lindsay Carnagie, in a letter (June 1838) to Sir C Lyell, remarks that Scotch farmers are afraid of putting lime on ploughed land until just before it is laid down for pasture, from a beUef that it has some tendency to sink. He adds : " Some 118 GREAT STONES Cn^r. Ill, The Sinking of great Stones through the Action of Worms. — When a stone of large size and of irregular shape is left on the surface of the ground, it rests, of conrso, on the more protuberant parts ; but worms soon fill up with their castings all the hollow spaces on the lower side ; for, as Hensen re- marks, they like the shelter of stones. As soon as the hollows are filled up, the worms eject the earth which they have swallowed beyond the circumference of the stones ; and thus the surface of the ground is raised all round the stone. As the burrows ex- cavated directly beneath the stone after a time collapse, the stone sinks a little.* Hence it is, that boulders which at some ancient years since, in autumn, I laid lime on an oat-stubble and ploughed it down ; thus bringing it into immediate contact with the dead vegetable matter, and securing its thorough mixture through the means of all the subsequent operations of fallow. In consequence of the above prejudice, I was considered to have committed a great fault ; but the result was eminently successful, and the practice was jpartially followed. By means of Mr. Darwin's observations, I think the prejudice will be removed." * This conclusion, which, as we shall immediately see. is fully justifipd,isofsome little importance, as the so-called bench-stones, which sun-eyors fix in the ground as a record of their levels, may in time become false standards. My son Horace intends al »ome future period to ascertain how far this has occurred. CiiAP. III. UNDERMINED BY WORMS. 149 period have rolled down from a rocky moun- tain or cliff on to a meadow at its base, are always somewliat embedded in the soil ; and, when removed, leave an exact impression of their lower surfaces in the nnder-lying fine mould. If, however, a boulder is of such huge dimensions, that the earth beneath is kept dry, such earth will not be inhabited by worms, and the boulder will not sink into the ground. A lime-kiln formerly stood in a grass-field near Leith Hill Place in Surrey, and was pulled down 35 years before my visit ; all the loose rubbish had been carted away, excepting three large stones of quartzose sandstone, which it was thought might here- after be of some use. An old workman re- membered that they had been left on a bare surface of broken bricks and mortar, close to the foundations of the kiln ; but the whole surrounding surface is now covered with turf and mould. The two largest of these stones had never since been moved ; nor could this easily have been done, as, when I had them removed, it was the work of two men with levers. One of these stones, and not the 150 GREAT STONES Chap. III. largest, was 64 inches long, 17 inches broad, and from 9 to 10 inches in thickness. Its lower surface was somewhat protuberant in the middle ; and this part still rested on broken bricks and mortar, showing the truth of the old workman's account. Beneath the brick rubbish the natural sandy soil, full of fragments of sandstone was ibund ; and this could have yielded very little, if at all, to the \veight of the stone, as might have been expected if the sub-soil had been clay. The surface of the field, for a distance of about 9 inches round the stone, gradually sloped up to it, and close to the stone stood in most places about 4 inches above the surrounding ground. The base of the stone was buried from 1 to 2 inches beneath the gen(?ral level, and the upper surface projected about 8 inches above this level, or about 4 inches above the sloping border of turf. After tl.e removal of the stone it became evident that one of its pointed ends must at first have stood clear above the ground by some inches, but its upper surface was now on a level v^ith the surrounding turf. When the stone v/as removed, an exact cast of its lowei Chap. III. UNDERMINED BY WORMS. 151 side, forming a shallow crateriform hollow, was left^ the inner surface of which consisted of fine black mould, excepting where the more protuberant parts rested on the brick- tubbish. A transverse section of this stone, together with its bed, drawn from measure- ments made after it had been displaced, is here given on a scale of ^ inch to a foot (Fig. 6). The turf-covered border which irmtP^^ . ^J:!ii^l ^ ^-v Fig. 6. Transverse section across a large stone, which had lain on a grass-field for 35 years. A A, general level of the field. The underlying brick rubbish has not been represented. Scale i inch to one foot. sloped up to the stone, consisted of fine vegetable mould, in one part 7 inches in thickness. This evidently consisted of worm- castings, several of which had been recently ejected. The whole stone had sunk in the thirty-fi.ve years, as far as I could judge, about 1^- inch ; and this must have been due 11 152 GREAT STONES Chap. Ill to the brick-rubbish beneath the more pro- tuberant parts having been undermined by worms. At this rate the upper surface of the stone, if it had been left undisturbed, would have sunk to the general level of the field in 247 years ; but before this could have occurred, some earth would have been washed down by heavy rain from the castings on the raised border of turf over the upper surface of the stone. The second stone was larger than the one just described, viz., 67 inches in length, 39 in breadth, and 15 in thickness. The lower surface was nearly flat, so that the worms must soon have been compelled to eject their castings beyond its circumference. The stone as a whole had sunk about 2 inches into the ground. At this rate it would have required 262 years for its upper surface to have sunk to the general level of the field. The up- wardly sloping, turf-covered border round the stone was broader than in the last case, viz., from 14 to 16 inches; and why this should be so, I could see no reason. In most parts this border was not so high as in the last case, viz., from 2 to 2| inches, but in one Chap. III. UNDERMINED BY WOEMS. 153 place it was as much as 5^. Its average height close to the stone was prohably about 3 inches, and it thinned out to nothing. If so, a layer of fine earth, 15 inches in breadth and 1^ inch in average thickness, of sufficient length to surround the whole of the much elongated slab, must have been brought up by the worms in chief part from beneath the stone in the course of 35 years. This amount would be amply sufficient to account for its having sunk about 2 inches into the ground ; more especially if we bear in mind that a good deal of the finest earth would have been washed by heavy rain from the castings ejected on the sloping border down to the level of the field. Some fresh castino-s o were seen close to the stone. Nevertheless, on digging a large hole to a depth of 18 inches where the stone had lain, only two worms and a few burrows were seen, although the soil was damp and seemed favourable for worms. There were some large colonies of ants beneath the stone, and possibly since their establishment the worms had decreased in number. The third stone was only about half as 154 GREAT STONES Chap. TIT. large as the others ; and two strong boys could together have rolled it over. I have no doubt that it had been rolled over at a moderately recent time, for it now lay at some distance from the two other stones at the bottom of a little adjoining slope. It rested also on fine earth, instead of partly on brick-rubbish. In agreement with this con- clusion, the raised surrounding border of turf was only 1 inch high in some parts, and 2 inches in other parts. There were no colonies of ants beneath this stone, and on digging a hole w^here it had lain, several burrows and worms were found. At Stonehenge, some of the outer Druidical stones are now prostrate, having fallen at a remote but unknown period ; and these have become buried to a moderate depth in the ground. They are surrounded by sloping borders of turf, on which recent castings were seen. Close to one of these fallen stones, which was 17 ft. long, 6 ft. broad, and 28. | inches thick, a hole was dug ; and here the vegetable mould was at kast 9^ inches in thickness. At this depth a flint was found, and a little higher up on one side of the hole Chap. III. UNDERMINED BY WORMS. 155 a fragment of glass. The base of the stone Jay about 9^ incbes beneath the level of the surrounding ground, and its upper surface 1 9 inches above the ground. A hole was also dug close to a second huge stone, which in falling had broken into two pieces; and this must have happened long ago, judging from the weathered aspect of the fractured ends. The base was buried to a depth of 10 inches, as was ascertained by driving an iron skewer horizontally into the ground beneath it. The vegetable mould forming the turf-covered sloping border round the stone, on which many castings had re- cently been ejected, was 10 inches in thick- ness ; and most of this mould must have been brought up by worms from beneath its base. Ai a distance of 8 yards from the stone, the mould was only 5 J inches in thickness (with a piece of tobacco pipe at a depth of 4 inches), and this rested on broken flint and chalk which could not have easily yielded to the pressure or weight of the stone. A straight rod was fixed horizontally (by the aid of a spirit-level) across a third fallen stone, which was 7 feet 9 inches long ; and the 156 GREAT STONES Chap. III. contour of the projecting parts and of the ad- joining ground, which was not quite level, was thus ascertained, as shown in the ac- companying diagram (Fig. 7) on a scale of Grass Fig. 7. Section thrmigh one of the fallen Dmidical stones at Stonehenge, showing how much it had sunk into the ground. Scale h inch to 1 foot. ^ inch to a foot. The turf-covered border sloped up to the stone on one side to a height of 4 inches, and on the opposite side to only 2i inches above the general level. A hole was dug on the eastern side, and the base of the stone was here found to lie at a depth of 4 inches beneath the general level of the ground, and of 8 inches beneath the top of the sloping turf-covered border. Sufficient evidence has now been given showing that small objects left on the surface Chap. III. UNDEKMINEB BY WOEMS. 157 of the land where worms abound soon gel buried, and that large stones sink slowly downwards through the same means. Every step of the process could be followed, from the accidental deposition of a single casting on a small object lying loose on the surface, to its being entangled amidst the matted roots of the turf, and lastly to its being embedded in the mould at various depths beneath the surface. When the same field was re-ex- amined after the interval of a few years, such objects were found at a greater depth than before. The straightness and regularity of the lines formed by the embedded objects, and their parallelism with the surface of the land, are the most striking features of the case ; for this parallelism shows how equably the worms must have w^orked; the result being, however, partly the effect of the wash- ing down of the fresh castings by rain. The specific gravity of the objects does not affect their rate of sinking, as could be seen by porous cinders, burnt marl, chalk and quartz pebbles, having all sunk to the same depth within the same time. Considering the nature of the substratum, which at Leith Hill L58 NUMBER OF WORMS. Chap. III. Place was sandy soil including' many bits of rock, and at Stonehenge, clialk-rubble with broken flints; considering, also, the presence of the turf-covered sloping border of mould round the great fragments of stone at botb tliese places, their sinking does not appear to have been sensibly aided by their weight, though this was considerable.* Oil the number of ivorms which live within a given space. — We will now show, firstly, what a vast number of worms live unseen by us beneath our feet, and, secondly, the actual weight of the earth which they bring up to the surface within a given space and within a given time. Hensen, who has published so full and interesting an account of the habits of worms,! calculates, from the number which he found in a measured space, that there must exist 133,000 living worms in a hectare of » Mr. R. Mallet remarks (' Quarterly Journal of Geolog. Soc, vol. xxxiii., 1877, p. 745) that " the extent to which the ground beneath the foundations of ponderous architectural structures, FiCli as cathedral towers, has been known to become compressed, is as remarkable as it is instructive and curious. The amount of depression in some cases may be measured by feet." He i'lstances the Tower of Pisa, but adds that it was founded on " vlense clay." t ' Zoitschrift fiir wissensch. Zoolog.' Bd. xxviii., 1877, p. 354 Ceap III. KUMBER OF WORMS. 159 land, or 53,767 in an acre. This latter Dinnber of worms would weigh 356 pounds, raking Hensen's standard of the weight of a ?gingle worm, namely, one gram. It should, however, be noted that this calculation is founded on the numbers found in a garden, and Hensen believes that worms are here twice as numerous as in corn-fields. The above result, astonishing though it be, seems to me credible, judging from the number of worms which I have sometimes seen, and from the number daily destroyed by birds without the species being exterminated. Some barrels of bad ale were left on Mr. Miller's land,* in the hope of making vinegar, but the vinegar proved bad, and the barrels were upset. It should be premised that acetic acid is so deadly a poison to worms that Perrier found that a glass rod dipped into this acid and then into a considerable body of ;vater in which worms were immersed, in- variably killed them quickly. On the morn- ing after the barrels had been upset, " the '' heaps of worms which lay dead on the • See Mr. Dancer's paper in ' Proc. Phil. Soc. of Manchester, 1877, p. 248. 160 WEIGHT OF EARTH Chap. IIL " ground were so amazing, that if Mr. Miller '' had not seen them, he could not have '•thought it possible for such numbers to " have existed in the space." As further evi- dence of the large number of worms which live in the ground, Hensen states that he found in a garden sixty-four open burrows in a space of 14i square feet, that is, nine in 2 square feet. Bat the burrows are some- times much more numerous, for when digging in ^ grass-field near Maer Hall, I found a cake of dry earth, as large as my two open hands, which was penetrated by seven bur- rows, as large as goose-quills. Weight of the earth ejected from a single burrow^ and from all the burrows within a given space. — With respect to the weight of the earth daily ejected by worms, Hensen found that it amounted, in the case of some worms which he kept in confinement, and which he appears to have fed with leaves, to only 0*5 gram, or less than 8 grains per diem. But a very much larger amount must be ejected by worms in their natural state, at the periods when they consume earth as food instead of leaves, and when they are Chap. III. BROUGHT UP BY WORMS. 161 making deep burrows. This is rendered almost certain by the following weights of the castings thrown up at tlie mouths of single burrows ; the whole of which appeared to have been ejected within no long time, as was certainly the case in several instances. The castings were dried (excepting in one specified instance) by exposure during many days to the sun or before a hot fire. Weight of the Castings accumulated at the mouth of a single buerow. Ounces. (1.) Down, Kent (sub-soil red clay, full of flints, over-\ lying the chalk). The largest casting which 1 1 could find on the flanks of a steep valley, the? 3*98 sub-soil being here shallow. In this one case, the casting was not well dried .. .. ,. ..^ (2.) Down. — Largest casting which I could find (con- sisting chiefly of calcareous matter), on extremely poor pasture land at the bottom of the valley mentioned under (1.) (3.) Down. — A large casting, but not of unusual size, j from a nearly level field, poor pasture, laid down in \ 1'22 grass about 35 years before.. .. .. .. ) (4.) Down. — Average weight of 11 not large castings] ejected on a sloping surface on my lawn, after they I ^ _ had suffered some loss of weight from being exposed [ during a considerahle length of time to rain .. ) (5.) Near Nice in France. — Average weight of 121 castings of ordinary dimensions, collected by Dr. King on land which had not been mown for a long time and where worms abounded, viz., a lawn pro- tected by shrubberies, near the sea ; soil sandy and calcareous ; the.se castings had been exposed for some time to rain, before being collected, and must have .ost some weight by disintegration, but they still re- tained tV.rir form 3-8'; 1-37 162 WEIGHT OF EARTH Chap. Ill "Weight of the Castings accumulated at the mouth OF A SINGLE BuRROW — continued. Dunces. (6.) The heaviest of the above twelve castings .. 1*76 (7.) Lower Bengal. — Avtiage weight of 22 castings,! collected by Mr. J. Scott, and stated by him to havei 1*24 been thrown up in the course of one or two nights ) (8.) The heaviest of the above 22 castings .. ,. 2 '09 (9.) Nilgiri Mountains, S. India ; average weight of^ the 5 largest castings collected by Dr. King. They I q.ik had been exposed to the rain of the last monsoon, j and must have lost some weight .. .. ..J (10.) The heaviest of the above 5 castings .. .. 4" 34 In this table we see that castings which had been ejected at the mouth of the same burrow, and which in most cases appeared fresh and always retained their vermiform configuration, generally exceeded an ounce in weight after being dried, and sometimes nearly equalled a quarter of a pound. On the Nilgiri moun- tains one easting even exceeded this latter weight. The largest castings in England were found on extremely poor pasture- land ; and these, as far as I have seen, are generally larger than those on land producing a rich vegetation. It would appear that worms ];ave to swallow a greater amount of earth 0J1 poor than on rich land, in order to obtain Bufficient nutriment. With respect to the tower-like castings Chap. III. BROUGHT UP BY WORMS. 163 near Nice (Nos. 5 and 6 in the above table)^ Dr. King often found five or six of them on a square foot of surface ; and these, judging from their average weight, would have weighted together 7^ ounces ; so that the weight of those on a square yard would have been 4 lb. 3 J oz. Dr. King collected, near the close of the year 1872, all the castings which still retained their vermiform shape, whether broken down or not, from a square foot, in a place abounding with worms, on the summit of a bank, where no castings could have rolled down from above. These castings must have been ejected, as he judged from their appearance in reference to the rainy and dry periods near Nice, within the previous five or six months ; they weighed 9^ oz., or 5 lb. 5^ oz. per square yard. After an interval of four months, Dr. King collected all the castings subsequently ejected on the same square foot of surface, and they weighed 2^oz., or lib. 6 J oz. per square yard. Therefore within about ten months, or we will say for safety's sake within a year, 12 oz. of castings were thrown up on this one square foot, or 6*75 pounds on the square 164 WEIGHT OF EARTH Chap. TIL yard ; and tins would give 14*58 tons per acre. In a field at the bottom of a valley in the chalk (see No. 2 in the foregoing table), a square yard was measured at a spot where very large castings abounded ; they appeared, however, almost equally numerous in a few other places. These castings, which retained perfectly their vermiform shape, were col- lected ; and they weighed when partially dried, 1 lb. 13^ oz. This field had been rolled with a heavy agricultural roller fifty-two days before, and this would certainly have flattened every single casting on the land. The weather had been very dry for two or three weeks before the day of collection, so that not one casting appeared fresh or had been recently ejected. We may therefore assume that those which were weighed had been ejected within, we will say, forty days from the time when the field was rolled, — that is, twelve days short of the whole inter- vening period. I had examined the same part of the field shortly before it was rolled, and it then abounded with fresh castings. Worms do not work in dry weather during Chap. III. BKOUGIIT UP BY WORMS. 165 the summer, or in winter during severe frosts. If we assume that they work for only half the year — though this is too low an estimate ' — then the worms in this field would eject during the year, 8*387 pounds per square yard; or 18'12 tons per acre, assuming the wdiole surface to be equally productive in castings. In the foregoing cases some of the necessary data had to be estimated, but in the two following cases the results are much more trustworthy. A lady, on whose ac- curacy I can implicitly rely, offered to collect during a year all the castings thrown up on two separate square yards, near Leith Hill Place, in Surrey. The amount collected was, however, somewhat less than that originally ejected by the worms ; for, as I have repeatedly observed, a good deal of the finest earth is washed away, whenever castings are thrown up during or shortly before heavy rain. Small portions also adhered to the surrounding blades of grass, and it required too much time to detach every one of them. On sandy soil, as in the present instance, castings are liable to crumble after dry weather, and 163 WEIGHT OF EARTH Chap. IH particles were thus o^ten lost. The lady also occasionally left home for a week or iwo^ and at such times the castings must have suffered still greater loss from exposure to the weather. These losses were, however, compensated to some extent by the collections having been made on one of the squares for four days, and on the other square for two days more than the year. A space was selected (October 9th, 1870) on a broad, grass-covered terrace, which had been mowed and swept during many years. It faced the south, but was shaded during part of the day by trees. It had been formed at least a century ago by a great accumulation of small and large fragments of sandstone, together with some sandy earth, rammed down level. It is probable that it was at first protected by being covered with turf. This terrace, judging from the number of castings on it, was rather unfavourable for the existence of worms, in comparison with the neighbouring fields and an upper terrace. It was indeed surprising that as many worms could live here as were seen ; for on digging a hole in this terrace, the black vegetable Chap. III. BROUGHT UP BY WORMS. 167 mould together with the turf was ouly four inches in thickness, beneath which lay the level surface of light-coloured sandy soil, with many fragments of sandstone. Before any castings were collected all the previously existing ones were carefully removed. The last day's collection was on October 14th, 1871. The castings were then well dried before a fire ; and they weighed exactly 3 J lbs. This would give for an acre of similar land 7*56 tons of dry earth annually ejected by worms. The second square was marked on un- enclosed common land, at a height of about 700 ft. above the sea, at some little distance from Leith Hill Tower. The surface was clothed with short, fine turf, and had never been disturbed by the hand of man. The spot selected appeared neither particularly favourable nor the reverse for worms ; but I have often noticed that castings are especially abundant on common land, and this may, perhaps, be attributed to the poorness of the soil. The vegetable mould was here between three and four inches in thickness. As this spot was at some distance from the 12 168 WEIGHT OF EARTH Chap. III. house where the lady lived, the castings were not collected at such short intervals of time as those on the terrace ; consequently the loss of fine earth during rainy weather must have been greater in this than in the last case. The castings moreover were more sandy, and in collecting them during dry weather they sometimes crumbled into dust, and much was thus lost. Therefore it is certain that the worms brought up to the surface considerably more earth than that which was collected. The last collection was made on October 27th, 1871 ; i.e., 367 days after the square had been marked out and the surface cleared of all pre-existing castings. The collected castings, after being well dried, weighed 7*453 pounds; and this would give, for an acre of the same kind of land, 16*1 tons of annually ejected dry earth. Summary of the four foregoing Cases. (1.) Castings ejected near Nice within about a year, collected by Dr. King on a square foot of surface, calculated to yield per acre 14*58 tons. (2.) Castings ejected during aoout 45 days on a square yard, in a field of poor pasture at the bottom of a large valley in the Chalk, calculated to yield annually per acre 18*12 tons. (3.) Castings collected from a square yard on an old terrace at Chap. III. BKOUGHT UP BY WOEMS. 169 Leith Hill Place, during 369 days, calculated to yield annually per acre 7 ' 56 tons. (4.) Castings collected from a square yard on Leith Hill Common during 367 days, calculated to yield annually per acre 16*1 tons. The thickness of the layer of mouldy which castings ejected during a year would form if uniformly spread out. — As we know from the two last cases in the above summary, the weight of the dried castings ejected by worms during a year on a square yard of surface, I wished to learn how thick a layer of ordinary mould this amount would form if spread uni- formly over a square yard. The dry castings were therefore broken into small particles, and whilst being placed in a measure were well shaken and pressed down. Those col- lected on the Terrace amounted to 124*77 cubic inches ; and this amount, if spread out over a square yard, would make a layer •09612 inch in thickness. Those collected on the Common amounted to 197*56 cubic inches, and would make a similar layer *1524 inch in thickness. These thicknesses must, however, be cor- rected, for the triturated castings, after being well shaken down and pressed, did not make 170 THICKNESS OF THE MOULD Chap. III. nearly so compact a mass as vegetable mould, though each separate particle was very compact. Yet mould is far from being com- pact, as is shown by the number of air- bubbles which rise up when the surface is flooded with water. It is moreover pene- trated by many fine roots. To ascertain ap- proximately by how much ordinary vegetable mould would be increased in bulk by beiiig broken up into small particles and then dried, a thin oblong block of somewhat argillaceous mould (with the turf pared off) was measured before being broken up, was well dried and again measured. The drying caused it to shrink by ^ of its original bulk, judging from exterior measurements alone. It was then triturated and partly reduced to powder, in the same manner as the castings had been treated, and its bulk now exceeded (notwithstanding shrinkage from drying) by -^ that of the original block of damp mould. Therefore the above calculated thickness of the layer, formed by the castings from the Terrace, after being damped and spread over a square yard, would have to be reduced by yV» ^^^^ ^^^^ ^^i^^ reduce the layer to '09 of an inch, so that a Chap. III. ANNUALLY ACCUMULATED. 171 layer '9 inch in thickness would be formed in the course of ten years. On the same prin- ciple the castings from the Common would make in the course of a single year a layer •1429 inch, or in the course of 10 years 1'429 inch, in thickness. We may say in round numbers that the thickness in the former case would amount to nearly 1 inch, and in the second case to nearly IJ inch in 10 years. In order to compare these results with those deduced from the rates at which small objects left on the surfaces of grass fields become buried (as described in the early part of this chapter), we will give the following summary : — BlTMMARY OF THE THICKNESS OF THE MoULD ACCUMULATED OVER Objects left strewed on the Surface, in the COURSE OF TEN YEARS. The accumulation of mould during 14| years on the surface of a dry, sandy, grass-field near Maer Hall, amounted to 2*2 inches in 10 years. The accumulation during 21^ years on a swampy field near Maer Hall, amounted to nearly 1*9 inch in 10 years. The accumulation during 7 years on a very swampy field near Maer Hall amounted to 2 • 1 inches in 10 years. The accumulation during 29 years, on good, argillaceous pasture-land over the Chalk at Down, amounted to 2*2 inches in 10 years. The accumulation durmg 30 years on the side of a valley over 172 THICKNESS OF THE MOULD Chap. III. the Chalk at Down, the soil being argillaceous, very poor, and only just converted into pasture (so that it was for some years unfavourable for worms), amounted to 0*83 inches in 10 years. In these cases (excepting the last) it may be seen that the amount of earth brouglit to the surface during 10 years is somev^hat greater than that calculated from the castings which were actually weighed. This excess may be partly accounted for by the loss which the weighed castings had previously under- gone through being washed by rain, by the adhesion of particles to the blades of the sur- rounding grass, and by their crumbling wlien dry. Nor must we overlook other agencies which in all ordinary cases add to the amount of mould, and which would not be included in the castings that were collected, namely, the fine earth brought up to the surface by burrowing larvge and insects, espe- cially by ants. The earth brought up by moles generally has a somewhat different appearance from vegetable mould ; but after a time would not be distinguishable from it. In dry coun- tiies, moreover the wind plays an important part in carrying dust from one place to another, and even in England it must add to the mould Chap. HI. ANNUALLY ACCUMULATED. 173 on fields near great roads. But in our county these latter several agencies appear to be of quite subordinate importance in comparison with the action of worms. We have no means of judging how great a weight of earth a single full-sized worm ejects during a year. Hensen estimates that 53,767 worms exist in an acre of land; but this is founded on the number found in gardens, and he believes that only about half as many live in corn-fields. How many live in old pasture land is unknown ; but if we assume that half the above number, or 26,886 worms live on such land, then taking from the previous summary 15 tons as the weight of the castings annually thrown up on an acre of land, each worm must annually eject 20 ounces. A fuli- sized casting at the mouth of a single burrow often exceeds, as we have seen, an ounce in weight ; and it is probable that worms eject more than 20 full-sized castings during a year. If they eject annually more than 20 ounces, we may infer that the worms which live in an acre of pasture land must be less than 26,886 in number. Worms live chiefly in the superficial mould, 174 THICKNESS OF THE MOULD Chap. HI. which is usually from 4 or 5 to 10 and even 1 2 inches in thickness ; and it is this mould which passes over and over again through their bodies and is brought to the surface. But worms occasionally barrow into the sub- soil to a much greater depth, and on such occasions they bring up earth from this greater depth ; and this process has gone on for countless ages. Therefore the superficial layer of mould would ultimately attain, though at a slower and slower rate, a thick- ness equal to the depth to which worms ever burrow, were there not other opposing agencies at work which carry away to a lower level some of the finest earth which is continually being brought to the surface by worms. How great a thickness vegetable mould ever attains, I have not had good opportunities for observing; but in the next chapter, when we consider the burial of ancient buildings, some facts will be given on this head. In the two last chapters we shall see that the soil is actually increased, though only to a small degree, through the agency of worms; but their chief work ia to sift the finer from the coarser particles, to Chap. III. ANNUALLY ACCUMULATED. 175 mingle the whole with vegetable debris, and to saturate it with their intestinal secretions. FinaJlj, no one who considers the facts given in this chapter — on the burying of small objects and on the sinking of great stones left on the surface— on the vast number of worms which live within a moderate extent of ground — on the weight of the castings ejected from the mouth of the same burrow — on the weight of all the cast- ings ejected within a known time on a measured space — will hereafter, as I believe, doubt that worms play an important part in nature. CHAPTER IV. THE PART WHICH WORMS HAVE PLATED IX THE BURIAL OF ANCIENT BUILDINGS. The accumulation of rubbisli on the sites of great cities inde- pendent of the action of worms — The burial of a Roman villa at Abinger — The floors and walls penetrated by worms — Subsidence of a modern pavement — The buried pavement at Beaulieu Abbey — Roman villas at Chedworth and Brading — The remains of the Roman town at Silchester — The nature of the debris by which the remains are covered — The penetration of the tesselated floors and walls by worms — Subsidence of the floors — Thickness of the mould — The old Roman city of Wroxeter — Thickness of the mould — Depth of the foundations of some of the Buildings — Conclusion. Archaeologists are probably not aware how much tbey ow'G to worms for the preservation of many ancient objects. Coins, gold orna- ments, stone implements, &c., if dropped on the surface of the ground, will infallibly be buried by the castings of worms in a few years, and w^ill thus be safely preserved, until the land at some future time is turned up For instance, many years ago a grass-field Chap. IY. OF ANCIENT BUILDINGS. 177 was ploughed on the northern side of the Severn, not far from Shrewsbury ; and a surprising number of iron arrow-heads were found at the bottom of the furrows_, which, as Mr. Blakeway, a local antiquary, believed, were relics of the battle of Shrewsbury in the year 1403, and no doubt had been originally left strewed on the battle-field. In the present chapter I shall show that not only implements, &c., are thus preserved, but that the floors and the remains of many ancient buildings in England have been buried so effectually, in large part through the action of worms, that they have been discovered in recent times solely through various accidents. The enormous beds of rubbish, several yards in thickness, which underlie many cities, such as Rome, Paris, and London, the lower ones being of great antiquity, are not here referred to, as they have not been in any way acted on by worms. When we con- sider how much matter is daily brought into a great city for building, fuel, clothing and food, and that in old times when the roads were bad and the work of the scavenger was neglected, a comparatively small amount 178 BURIAL OF THE REMAINS Chap. IV was carried away, we may agree with Elie de Beaumont, who, in discussing this subject, says, " pour une voiture de materiaux " qui en sort, on y en fait entrer cent." * Nor should we overlook the effects of fires, the demolition of old buildings^ and the removal of rubbish to the nearest vacant space. Abinger, Surrey, — Late in the autumn of 1876, the ground in an old farm-yard at this place was dug to a depth of 2 to 2| feet, and the workmen found various ancient remains. This led Mr. T. H. Farrer of Abinger Hall to have an adjoining ploughed field searched. On a trench being dug, a layer of concrete, still partly covered with tesserae (small red tiles), and surrounded on two sides by broken- down walls, was soon discovered. It is believed f that this room formed part of the atrium or reception-room of a Roman villa. The walls of two or three other small rooms were afterwards discovered. Many fragments of pottery, other objects, and coins of several • * Le9ons de G^ologie pratique,' 1845, p. 142. \ A short account of this discovery was published in * The Times' of January 2, 1878; and a fuller account in * The Builder,' January 5, 1878. Chap. IV. OF ANCIENT BUILDINGS. 179 Roman emperors, datiug from 133 to 361, and perhaps to 375 A.D., were likewise found. -Also a half-penny of George 1., 1715. The presence of this latter coin seems an anomaly ; but no doubt it was dropped on the ground during the last century, and since then there has been ample time for its burial under a considerable depth of the castings of worms. From the different dates of the Roman coins we may infer that the building was long inhabited. It was probably ruined and deserted 1400 or 1500 years ago. I was present during the commencement of the excavations (August 20, 1877) and Mr. Farrer had two deep trenches dug at opposite ends of the atrium, so that I might examine- the nature of the soil near the remains. The field sloped from east to west at an angle of about 7° ; and one of the two trenches, shown in the accompanying section (Fig. 8) was at the upper or eastern end. The diagram is on a scale of -^q of an inch to an inch ; but the trench, which was between 4 and 5 feet broad, and in parts above 5 feet deep, has necessarily been reduced out of all proportion. The fine mould over the floor 180 BURIAL OF THE REMAINS Chap. IV. Section throngli the foundations of a buried Roman yilla at Abinger. A A, vegetable mould ; B, dark earth full of stones, ]3 inches in thickness ; C, black mould ; D, broken morfar ; E, black mould ; F F, undisturbed sub-soil ; G, tesserse ; H. concrete I, nature unknown ; W, buried wall. Chap. IV. OF ANCIENT BUILDINGS. 181 of the atrium varied in thickness from 11 to 16 inches; and on the side of the trench in the section was a little over 1 3 inches. After the mould had been removed, the floor appeared as a whole moderately level ; but it sloped in parts at an angle of 1°, and in one place near the outside at as much as 8° 30'* The wall surrounding the pavement was built of rough stones, and was 23 inches in thickness where the trench w^as dug. Its broken summit was here 13 inches, but in another part 15 inches, beneath the surface of the field, being covered by this thickness of mould. In one spot, however, it rose to within 6 inches of the surface. On two sides of the room, where the junction of the concrete floor with the bounding walls could be carefully examined, there was no crack or separation. This trench afterwards proved to have been dug within an adjoining room (11 ft. by 11 ft. 6 in. in size), the existence of which was not even suspected whilst I was present. On the side of the trench farthest from the buried wall (W), the mould varied from 9 to 14 inches in thickness; it rested on a mass (B'^ 182 BURIAL OF THE REMAINS Chap. IY. 23 inches thick of blackish earth, including many large stones. Beneath this was a thin bed of very black mould (C), then a layer of earth full of fragments of mortar (D), and then another thin bed (about 3 inches thick) (F) of very black mould, which rested on the undisturbed subsoil (F) of firm, yellowish, argillaceous sand. The 23-inch bed (B) was probably made ground, as this would have brought up the floor of the room to a level with that of the atrium. The two thin beds of black mould at the bottom of the trench evidently marked two former land-surfaces. Outside the walls of the northern room, many bones, ashes, oyster-shells, broken pottery and an entire pot were subsequently found at a depth of 16 inches beneath the surface. The second trench was dug on the western or lower side of the villa : the mould was here only 6|- inches in thickness, and it rested on a mass of fine earth full of stones, broken tiles and fragments of mortar, 34 inches in thickness, beneath which was the undisturbed sand. Most of this earth had probably been washed down from the upper part of the field, and the fragments of CuAP. IV OF ANCIEKT BUILDINGS. IS.S stones, tiles, &c., must have come from the immediately adjoining ruins. It appears at first sight a surprising fact that this field of light sandy soil should haxe been cultivated and ploughed during many years, and that not a vestige of these buildings should have been discovered. No one even suspected that the remains of a Roman villa lay hidden close beneath the surface. But the fact is less surprising when it is known that the field, as the bailiff believed, had never been ploughed to a greater depth than 4 inches. It is certain that when the land was first ploughed, the pavement and the surrounding broken walls must have been covered by at least 4 inches of soil, for other- wise the rotten concrete floor would have been scored by the ploughshare, the tesserae torn up, and the tops of the old walls knocked down. When the concrete and tesseras were first cleared over a space of 14 by 9 ft., the floor which was coated with trodden-down earth exhibited no signs of having been penetrated by worms ; and although the overlying fine mould closelv resembled that which in many 13 184 BURIAL OF THE REMAINS Chap. IV places has certainly been accumulated bj worms, yet it seemed hardly possible that this mould could have been brought up by wormp from beneath the apparently sound floor. It seemed also extremely improbable that the thick walls, surrounding the room and still united to the concrete, had been undermined by worms, and had thus been caused to sink, being afterwards covered up by their cast- ings. I therefore at first concluded that all the fine mould above the ruins had been washed down from the upper parts of the field ; but we shall soon see that this conclu- sion was certainly erroneous, though much fine earth is known to be washed down from the upper part of the field in its present ploughed state during heavy rains. Although the concrete floor did not at first appear to have been anywhere pene- trated by worms, yet by the next morning little cakes of the trodden-down earth had been lifted up by worms over the mouths of seven burrows, which passed thi-ough tho softer parts of the naked concrete, or between the interstices of the tesserge. On the third morning twen+y-five burrows were counted ; Chap. IV. OF ANCIENT BUILDINGS. 185 and hj suddenly lifting up the little cakes of earth, four worms were seen in the act of quickly retreating. Two castings were thrown up during the third night on the floor, and these were of large size. The season was not favourable for the full activity of worms, and the weather had lately been Lot and dry, so that most of the worms now lived at a considerable depth. In digging the two trenches many open burrows and some worms were encountered at between 30 and 40 inches beneath the surface ; but at a greater depth they became rare. One worm, however, was cut through at 48|, and another at 51^ inches beneath the surface. A fresh humus-lined burrow was also met with at a depth of 57 and another at Gfi^ inches. At greater depths than this, neither burrows nor worms were seen. As I wished to learn how many worms lived beneath the floor of the atrium — a space of about 14 by 9 feet — Mr. Farrer was so kind as to make observations for me, during the next seven weeks, by which time the worms in the surrounding country were in full activity, and were work- 186 BUKIAL OF THE REMAINS Cha?. TY ing near the surface. It is very improbable that worms should have migrated from the adjoining field into the small space of the atrium, after the superficial mould in which they prefer to live, had been removed. We may therefore conclude that the burrows and the castings which were seen here during the ensuing seven weeks were tlie work of the former inhabitants of the space. I will now give a few extracts from Mr. Farrer's notes. Aug. 2'jth, 1877; that is, five days after the floor had been cleared. On the previous night there had been some heavy rain, which washed the surface clean, and now the mouths of forty burrows were counted. Parts of the concrete were seen to be solid, and had never been penetrated by worms, and here the rain- water lodged. Sept. 5th. — Tracks of worms, made during the previous night, could be seen on the sur- face of the floor, and five or six vermiform castings had been thrown up. These were defaced. Sept. 12th. — During the last six days, the worms have not been active, though many castings have been ejected in the neighbour Chap. IV. OF ANCIENT BUILDINGS. 187 ins: fields ; but on tliis day the earth was a little raised over the mouths of the burrows, or castings were ejected, at ten fresh points. These were defaced. It should be understood that wdien a fresh barrow is sjDoken of, this generally means only that an old burrow has been re-opened. Mr. Farrer was repeatedly struck with the pertinacity with which the worms re-opened their old burrows, even w^hen no earth was ejected from them. I have often observed the same fact, and generally the mouths of the burrows are protected by an accumulation of pebbles, sticks or leaves. Mr. Farrer likewise observed that the worms living beneath the floor of the atrium often collected coarse grains of sand, and such httle stones as they could find, round the mouths of their burrows. Sept. 13th ; soft wet weather. The mouths of the burrows were re-opened, or castings were ejected, at 31 points; these w^ere all defaced. Sept. 14th ; 34 fresh holes or castings all defaced. Sept. 15th ; 44 fresh holes, only 5 castings ; ail defaced. 188 BUEIAL OF THE REMAINS Chap. IV. Sept. 18tb ; 43 fresli holes, 8 castings; all defaced. The number of castings on the surrounding fields was now very large. Sept. 19t]i ; 40 holes, 8 castings; all defaced. Sept. 22nd ; 43 holes, only a few fresh castings ; all defaced. Sept. 23rd ; 44 holes, 8 castings. Sept. 25th ; 50 holes, no record of the number of castings. Oct. 13th ; 61 holes, no record of the number of castings. After an interval of three years, Mr. Farrer, at my request, again looked at the concrete floor, and found the worms still at work. Knowing what great muscular power worms possess, and seeing how soft the concrete was in many parts, I was not surprised at its having been penetrated by their burrows ; but it is a more surprising fact that the mortar between the rough stones of the thick walls, surrounding the rooms, was found by Mr. Farrer to. have been penetrated by worms. On August 26th, that is, Rve days after the ruins had been exposed, he observed four Chap. IV. OF ANCIENT BUILDINGS. 189 open burrows on the broken summit of the eastern wall (W in Fig. 8) ; and, on Septem- ber 15th, other burrows similarly situated were seen. It should also be noted that in the perpendicular side of the trench (which was much deeper than is represented in Fig. 8) three recent burrows were seen, which ran obliquely far down beneath the base of the old wall. AYe thus see that many worms lived beneath the floor and the walls of the atrium at the time when the excavations were made ; and that they afterwards almost daily brought up earth to the surface from a considerable depth. There is not the slightest reason to doubt that worms have acted in this manner ever since the period when the concrete wa?< su£6.ciently decayed to allow them to penetrate it ; and even before that period they would have lived beneath the floor, as soon as it became pervious to rain, so that the so 1 beneath was kept damp. The floor and the walls must therefore have been continually undermined ; and fine earth must have been heaped on them during many centuries, perhaps for a thousand years. If the burrows 190 BUEIAL OF THE EEMAINS Chap. IV beneath the floor and walls, which it is prob- able were formerly as numerous as they now are, had not collapsed in the course of time in the manner formerly explained, the under- lying earth would have been riddled with pas- sages like a sponge ; and as this was not the case, we may feel sure that thev have collapsed. The inevitable result of such col- lapsing during successive centuries, will have been the slow subsidence of the floor and of the walls, and their burial beneath the accumu- lated worm-castings. The subsidence of a floor, whilst it still remains nearly horizontal, may at first appear improbable ; but the case presents no more real difficulty than that of loose objects strewed on the surface of a field, which, as we have seen, become buried several inches beneath the surface in the course of a few years, though still forming a horizontal layer parallel to the surface. The burial of the paved and level path on my lawn, which took place under my own observation, is an analogous case. Even those parts of the concrete floor which the worms could not penetrate would almost certainly have been imdermined, and would have sunk, like the great Chap. IV. OF ANCIENT BUILDINGS. 191 stones at Leith Hill Place and Stonehenge, for the soil would have been damp beneath them. But the rate of sinking of the dif- ferent parts would not have been quite equal, and the floor was not quite level. The foundations of the boundary walls lie, as shown in the section, at a very small depth beneath the surface ; they would therefore have tended to subside at nearly the same rate as the floor. But this would not have occurred if the foundations had been deep, as in the case of some other Roman ruins presently to be described. Finally, we may infer that a large part of the fine vegetable mould, which covered the floor and the broken-down walls of this villa, in some places to a thickness of 16 inches, was brought up from below by worms. P'rom facts hereafter to be given there can be no doubt that some of the finest earth thus brought up will have been washed down the sloping surface of the field during every heavy shower of rain. If this had not occurred a greater amount of mould would have accumu- lated over the ruins than that now present. But beside the castings of worms and some 192 BURIAL OF THE REMAINS Chap. IV earth brought up by iDsects, and some accu- mulation of dust, much fine earth will have been washed over the ruins from the upper parts of the field, since it has been under cultivation ; and from over the ruins to the lower parts of the slope ; the present thick- ness of the mould being the resultant of these several agencies. I may here append a modern instance of the sinking of a pavement, communicated to me in 1871 by Mr. Ramsay, Director of the Geological Survey of England. A passage without a roof, 7 feet in length by 3 feet 2 inches in width, led from his house into the garden, and was paved with slabs of Portland stone. Several of these slabs were 16 inches square, others larger, and some a little smaller. This pavement had subsided about 3 inches along the middle of the passage, and two inches on each side, as could be seen by the lines of cement by which the slabs had been originally joined to the walls. The pave- ment had thus become slightly concave along the middle ; but there w^as no subsidence at the end close to the house. Mr. Ramsaj^ Chap. IV. OF ANCIENT BUILDINGS. 193 could not account for this sinking, until he observed that castings of black mould were frequently ejected along the lines of junction between the slabs ; and these castings were regularly swept away. The several lines of junction, including those with the lateral walls, were altogether 39 feet 2 inches in length. The pavement did not present the appearance of ever having been renewed, and the house was believed to have been built about eighty-seven years ago. Con- sidering all these circumstances, Mr. Ramsay does not doubt that the earth brought up by the worms since the pavement was first laid down, or rather since the decay of the mortar allowed the worms to burrow through it, and therefore within a much shorter time than the eighty-seven years, has sufficed to cause the sinking of the pavement to the above amount, except close to the house, where the ground beneath would have been kept nearly dry. Beaulieu Abbey, Hampshire. — This abbey was destroyed by Henry YIIl., and there now remains only a portion of the southern aisle-wall. It is believed that the king had mobt of the stones carried away for building 194 BUEIAL OF THE REMAINS Chap. IV a castle ; and it is certain tliat they have been removed. The position of the nave-transept was ascertained not long ago by the foundations having been found ; and the |)lace is now marked by stones let into the ground. Where the abbey formerly stood, there now extends a smooth grass- covered surface, which resembles in all respects the rest of the field. The guardian, a very old man, said the surface had never been levelled in his time. In the year 1853, the Duke of Buccleuch had three holes dug in the turf within a few yards of one another, at the western end of the nave ; and the old tesselated pavement of the abbey was thus discovered. These holes were afterwards surrounded by brickwork, and protected by trap-doors, so that the pavement might be readily inspected and preserved. When my son William examined the place on January 5, 1872, he found that the pavement in the three holes lay at depths of 6|, 10 and Hi laches beneath the surrounding turf-covered surface. The old guardian asserted that he was often forced to remove worni'Castings from the 23avement ; and that he had done Chap. IV. OF ANCIENT BUILDINGS. 195 SO about six montlis before. My son collected all from one of the holes, the area of which was 5*32 square feet, and they weighed '7*97 ounces. Assuming that this amount ha.l accumulated in six months, the accumulation during a year on a square yard would be 1'68 pounds, which, though a large amount, is very small compared with wliat, as we have seen, is often ejected on fields and commons. When I visited the abbey on June 22, 1877, the old man said that he had cleared out the holes about a month before, but a good many castings had since been ejected. I suspect that he imagined that he swept the pavements oftener than he really did, for the conditions were in several re- spects very unfavourable for the accumulation of even a moderate amount of castings. The tiles are rather large, viz., about 5i inches square, and the mortar between them was in most places sound, so that the worms were able to bring up earth from below only at certain points. The tiles rested on a bed of concrete, and the castings in consequence con- sisted in large part (viz., in the proportion of 19 to 33) of particles of mortar, grains of 19(3 BURIAL OF THE REMAINS Chap. IV. sand, little fragments of rock, bricks or tile ; and such substances could hardly be agreeable, and certainly not nutritious, to worms. My son dug holes in several places within the former walls of the abbey, at a distance of several yards from the above described bricked squares. He did not find any tiles, though these are known to occur in some other parts, but he came in one spot to con- crete on which tiles had once rested. The fine mould beneath the turf on the sides of the several holes, varied in thickness from only 2 to 2 J inches, and this rested on a layer from 8 a to above 11 inches in thickness, consisting of fragments of mortar and stone- rubbish with the interstices compactly filled up with black mould. In the surrounding field, at a distance of 20 yards from the abbey, the fine vegetable mould was 11 inches thick. We may conclude from these facts that when the abbey was destroyed and the stones removed, a layer of rubbish was left over the whole surface, and that as soon as the worms were able to penetrate the decayed concrete and the joints between the tiles, they slowly Chap. IV. OF ANCIENT BUILDINGS. 197 filled up the interstices in the overlying rubbish with their castings, which were after- wards accumulated to a thickness of nearly three inches over the whole surface. If we add to this latter amount the mould between tlje fragments of stones, some five or six inches of mould must have been brought up from beneath the concrete or tiles. The con- crete or tiles will consequently have subsided to nearly this amount. The bases of the columns of the aisles are now buried beneath mould and turf. It is not probable that they can have been undermined by worms, for their foundations would no doubt have been laid at a considerable depth. If they have not subsided, the stones of which the columns were constructed must have been removed from beneath the former level of the floor. Chedu:orth^ Gloucestershire, — The remains of a large Roman villa were discovered here in 1866, on ground which had been covered with wood from time immemorial. No suspicion seems ever to have been enter- tained that ancient buildings lay buried here, until a gamekeeper, in digging for rabbits, 198 BURIAL OF THE REMAINS Chap. IV. encountered some remains.* But subse- quently the tops of some stone walls were de- tected in parts of the wood, projecting a little above the surface of the ground. Most of the coins found here belonged to Constans (who died 350 a.d.) and the Constant! ne family. My sons Francis and Horace visited the place in November 1877, for tlie sake of ascertaining what part worms may have played in the burial of these extensive re- mains. Bat the circumstances were not favourable for this object, as the ruins are sur- rounded on three sides by rather steep banks, do^vn which earth is washed during rainy weather. Moreover most of the old rooms have been covered with roofs, for the pro- tection of the elegant tesselated pavements. A few facts may, however, be given on the thickness of the soil over these ruins. Close outside the northern rooms there is a broken wall, the summit of which was covered by 5 * Several accounts of these ruins have been published ; the Dest is by Mr. James Farrer in ' Proc. Soc. of Antiquaries of Scotland,' vol. vi,, Part II., 1867, p. 278. Also J, W. Grover, 'Journal of the British Arch. Assoc' June 1866. Professor nuckman has likewise published a pamphlet, * Notes on the Rtimau Villa at Chcdwcrth,' 2nd edit. 1873: Cirencester. Chap. IV. OF ANCIENT BUILDINOS. 199 inches of black mould ; and in a hole dug on the outer side of this wall, where the ground had never before been disturbed, black mould, full of stones, 26 inches in thickness, v^m found, resting on the undisturbed sub- soil oi yellow clay. At a depth of 22 inches from the surface a pig's jaw and a fragment of a tile were found. When the excavations were first made, some large trees grew over the ruins ; and the stump of one has been left directly over a party-wall near the bath room, for the sake of showing the thickness of the superincumbent soil, which was here 38 inches. In one small room, which, after being cleared out, had not been roofed over, my sons observed the hole of a worm passing through the rotten concrete, and a living worm was found within the concrete. In another open room worm-castings were seen on the floor, over which some earth had by this means been deposited, and here grass now grew. JBrading, Isle of Wight. — A fine Roman villa was discovered here in 1880 ; and by the end of October no less than 18 chambers Mad been more or less clenrud. A coin dated 14 200 BURIAL OF THE REMAINS Chap. IV. 337 A.D. was found. My son William visited the place before the excavations were com- pleted ; and he informs me that most of tho floors were at first covered with much rubbish and fallen stones, having their interstices completely filled up with mould, abounding as the workmen said, with worms, above which there was mould without any stones. The whole mass was in most places from 3 to above 4 ft. in thickness. In one very large room the overlying earth was only 2 ft. 6 in. thick ; and after this had been re- moved, so many castings were thrown up between the tiles that the surface had to be almost daily swept. Most of the floors were fairly level. The tops of the broken- down walls were covered in some places by only 4 or 5 inches of soil, so that they were occasionally struck by the plough, but in other places they were covered by from 13 to 18 inches of soil. It is not probable that these walls could have been undermined by worms and subsided, as they rested on a foundation of very hard red sand, into which worms could hardly burrow. The mortar, however, between the stones of the walls of Chap. IV. OF ANCIENT BUILDINGS. 201 a hypocaust was found by my son to have been penetrated by many worm-burrows. The remains of this villa stand on land which slopes at an angle of about 3° ; and the land appears to have been long cultivated. There- fore no doubt a considerable quantity of fine earth has been washed down from the upper parts of the field, and has largely aided in the burial of these remains. Silchester, Hampshire. — The ruins of this small Roman town have been better pre- served than any other remains of the kind in England. A broken wall, in most parts from 15 to 18 feet in height and about 1^ mile in compass, now surrounds a space of about 100 acres of cultivated land, on which a farm-house and a church stand.* Formerly, when the weather was dry, the lines of the buried walls could be traced by the appear- ance of the crops ; and recently very exten- sive excavations have been undertaken by the Duke of Wellington, under the superin- tendence of the late Kev. J. Gr. Joyce, by which means many large buildings have been * These details are taken from the * Penny Encyclopa3dia, article, Hampshire. 202 BURIAL OF THE REMAINS Chap. IV discovered. Mr. Joyce made careful coloured sections, and measured the thickness of each bed of rubbish, whilst the excavations were in progress ; and he has had the kindness to send me copies of several of them. When my sons Francis and Horace visited these ruins^ he accompanied them, and added his notes to theirs. Mr. Joyce estimates that the town was in- habited by the Romans for about three cen- turies ; and no doubt much matter must have accumulated wnthin the walls during this long period. It appears to have been destroyed by fire, and most of the stones used in the buildings have since been carried away. These circumstances are unfavourable for as- certaining the part which w^orms have played in the burial of the ruins; but as careful sections of the rubbish overlying an ancient town have seldom or never before been made in England, I will give copies of the most characteristic portions of some of those made by Mr. Joyce. They are of too great length to be here introduced entire. An east and west section, 30 ft. in length, was made across a room in the Basilica, now Chap. IV. OF ANCIENT BUILDINGS. 203 called the Hall of the Merchants (Fig. 9). The hard concrete floor, still covered here and there with tesserae, was found at 3 ft» Fig. 9. Section within a room in the Basilica at SilcLester. Scale ^. 204 BURIAL OF THE REMAINS Chap. IV. beneath the surface of the field, which was here leveL On the floor there were two large piles of charred wood, one alone of which is shown in the part of the section here given. This pile w^as covered by a thin white layer of decayed stucco or plaster, above which was a mass, presenting a singu- larly disturbed appearance, of broken tiles, mortar, rubbish and fine gravel, together 27 inches in thickness. Mr. Joyce believes that the gravel was used in making the mortar or concrete, which has since decayed, some of the lime probably having been dissolved. The disturbed state of the rubbish may have been due to its having been searched for building stones. This bed was capped by fine vegetable mould, 9 inches in thickness. From these facts we may conclude that the Hall was burnt down, and that much rubbish fell on the floor, through and from which the worms slowly brought up the mould, now forming the surface of the level field. A section across the middle of another hall in th3 Basilica, 32 feet 6 inches in length, called the (Evarium, is shown in Fig. 10. It appears that we have here evidence of twc CUAP. IV. OF ANCIENT BUILDINGS. 205 fires, separated by an interval of time, during which the 6 inches of " mortar and concrete Ms .2 ^ 6 03 F \i 'I HI H ^^^B ■) Bu ^H^'E ^B ^K « ^V^ K H^L ^■^'If ^^^^K ^mx H ^ m-' ^H ^VtA B 1 |oK . ■ If^ ■^cpI^*| I ^^f4 ■ ^ K 1 K^^ ■ V/l ^Klk a/S^ ^ KB^iffi^ Fig. 10. Section within a hall in the Basilica at Silchester. Scale 3^- 206 BURIAL OF THE REMAINS Chap. IV. with broken tiles " was accumulated. Be- neath one of the layers of charred wood, a vahiable rehc, a bronze eagle, was found ; and this shows that the soldiers must have deserted the pkce in a panic. Owing to the death of Mr. Joyce, I have not been able to ascertain beneath which of the two layers the eagle was found. The bed of rubble overly- ing the undisturbed gravel originally formed, as I suppose, the floor, for it stands on a level with that of a corridor, outside the walls of the Hall; but the corridor is not shown in the section as here given. The vegetable mould was 16 inches thick in the thickest part; and the depth from the surface of the field, clothed with herbage, to the undisturbed gravel, was 40 inches. The section shown in Fig. 11 represents an excavation made in the middle of the town, and is here introduced because the bed of " rich "mould" attained, according to Mr. Joyce, the unusual thickness of 20 inches. Gravel lay at the depth of 48 inches from the surface but it was not ascertained whether this was in its natural state, or had been brought here and had been rammed down, as occurs in some other places. Chap. IV. OF ANCIENT BUILDINGS. 207 The section shown in Fig. 12 was taken in the centre of the Basilica, and though it was 5 feet in depth, the natural sub-soil was not Mould, 20 inches thick. Rubble wi'h broken t.les, 4 inches thick. Black decayed wood, in th.ckfi~t pait 6 inches thick. Fig. 11. Section in a block of buildings in the middle of the town of Silchester. reached. The bed marked "" concrete " was probably at one time a floor ; and the beds beneath seem to be the remnants of more ancient buildings. The vegetable mould was 208 BURIAL OF THE REMAINS Chap. IV. here only 9 inches thick. In some other sections, not copied, we likewise have im^ ^'^ - — 1 Mould, 9 inches thick. %:^ Ligh'-coloured earth with large pitces of broken tiles, 7 inches. Dai k, fine grained rubbish with small bits oi tiles 20 inches. Concrete, 4 inches. Stucco, 2 inches. Made bottom with frag- ments of tiles, 8 ibches. Fine-grained made ground, with the debrii of older buildings. Fig. 12. Section in the centre of the Basilica at Silchester. evidence of buildings having been erected over the ruins of older ones. In one case Chap. IV. OF ANCIENT BUILDINGS. 200 there was a layer of yellow clay of very unequal thickness between two beds of debris, the lower one of which rested on a floor with tesserse. The old broken walls appear some- times to have been roughly cut down to a uniform level, so as to serve as the founda- tions of a temporary building ; and iMr. Joyce suspects that some of these buildings were wattled sheds, plastered with clay, which would account for the above-mentioned layer of clay. Turning now to the points which more immediately concern us. Worm-castings were observed on the floors of several of the rooms, in one of which the tesselation was unusually perfect. The tesserye here con- sisted of little cubes of hard sandstone of about 1 inch, several of which were loose or projected slightly above the general level One or occasionally two open worm-burrows were found beneath all the loose tesserye. Worms have also penetrated the old walls of these ruins. A wall, which had just been exposed to view during the excavations then in progress, was examined : it was built of lar^e flints, and was 18 inches in thickness. 210 BURIAL OF THE REMAINS Chap. IV It appeared sound, but when the soil was removed from beneath, the mortar in the lower part was found to be so much decayed that the flints fell apart from their own weight. Here, in the middle of the wall, at a depth of 29 inches beneath the old floor and of 49 J inches beneath the surface of the field, a living worm was found, and the mortar was penetrated by several burrows. A second wall was exposed to view for the first time, and an open burrow was seen on its broken summit. By separating the flints this burrow was traced far down in the interior of the wall ; but as some of the flints cohered firmly, the whole mass was disturbed in pulling down the wall, and the burrow could not be traced to the bottom. The foundations of a third wall, which appeared quite sound, lay at a depth of 4 feet beneath one of the floors, and of course at a con- siderably greater depth beneath the level of the ground. A large flint was wrenched out of the wall at about a foot from the base, and this required much force, as the mortar was sound ; but behind the flint in the middle of the wall, the mortar was friable, Chap. IV. OF ANCIENT BUILDINGS. 213. and here there were worm-burrows. Mr. Joyce and my sons were surprised at the blackness of the mortar in this and in several other cases, and at the presence of mould in the interior of the walls. Some may have been placed there by the old builders instea 1 of mortar ; but we sliould remember that worms line their burrows with black humus. Moreover open spaces would almost certainly have been occasionally left between the large irregular flints ; and these spaces, we may feel sure, would be filled up by the worms witb their castings, as soon as they were able to penetrate the wall. Rain-water, oozing down the burrows would also carry fine dark-coloured particles into every crevice. Mr. Joyce was at first very sceptical about the amount of work which I attributed to worms ; but he ends his notes with reference to the last-mentioned wall by saying, " This " case caused me more surprise and brought *' more conviction to me than any other. I " should have said, and did say, that it was '' quite impossible such a wall could have been '* penetrated by earth-worms." In almost all the rooms the pavement has 212 BUKIAL OF THE EEMAINS Chap. IV. ui CO 'T^ ^. > to ^ fe sunk considerably, especi- ally towards the middle ; and this is shown in the three following sections. The measurements were made by stretching a string tightly and horizontally over the floor. The sec- tion, Fig. 13, was taken from north to south across a room, 18 feet 4 incVies in length, with a nearly per- fect pavement, next to the "Red Wooden Hut." In the northern half, the sub- sidence amounted to 5|: inches beneath the level of the floor as it now stands close to the walls; and it was greater in the northern than in the southern half ; but, according to Mr. Joyce, the entire pavement has obviously subsided. In several places, the tessera3 appeared as if drawn a little away from the walls ; whilst Chap. IV. OF ANCIENT BUILDINGS. 213 in other places tliey were still in close contact with them. In Fig. 14^ we see a section across tlie paved floor of the southern corridor or ambulatory of a quadrangle, in an excavation made near *' The Spring." The floor is 7 feet 9 inches wide, and the broken-down walls now project only | of an inch above its level. The field, which was in pasture, here sloped from north to south, at an angle of 3° 40'. The nature of the ground on each side of the corridor is shown in the section. It consisted of earth full of stones and other debris, capped with dark vegetable mould which was thicker on the lower or southern than on the northern side. The pavemeni was nearly level along lines parallel to the side-walls, but had sunk in the middle as much as 7f inches. A small room at no great distance from that represented in Fig. 13, had been enlarged by the Roman occupier on the southern side, by an addition of 5 feet 4 inches in breadth. For this purpose the southern wall of the house had been pulled down, but the foundations of the old wall had been left buried at a little depth 214 BURIAL OF THE REMAINS Chap, IY ■5 '^ ■B ^ o i-G Isfl ■^ «3 -'cr ■-a • 2 "^ © O d ^ ^ PH "m •T3 -^ 5:^ 11 •C 1 §1 eS cc tH ^ fe , o fcJD O &D CC d s '^ ^ d 0) ■Td a ^ ^ ^ r^ rd ^ -^^ O c^ c3 fH fe O rd f^ d 8 I § M O f-l 1= d rj a, O ^-1 ^ ' -. d d £ a O) 03 a p.^ J-*^ '^ O =« C rd gn ^ •T3 O q; ••-I n:j ^ •^, ^ r^ ^ g o o ^ H? ■5 r^ (U n M^ m |t^ t3 o ^: rO o Oi Chap. IV. OF ANCIENT BUILDINGS. 217 than the other half without any assignable cause. In a bricked passage to Mr. Joyce's own house, laid dowm only about six year8 ago, the same kind of sinking has occurred as in the ancient buildings. Nevertheless it does not appear probable that the whole amount of sinking can be thus accounted for. The Eoraan builders excavated the ground to an unusual depth for the foundations of their walls, which were thick and solid ; it is therefore hardly credible that they should have been careless about the solidity of the bed on which their tesselated and often ornamented pavements were laid. The sink- ing must, as it appears to me, be attributed in chief part to the pavement having been undermined by worms, which w^e know are still at work. Even Mr. Joyce at last ad- mitted that this could not have failed to have produced a considerable effect. Thus also the large quantity of fine mould overlying the pavements can be accounted for, the presence of w'hich would otherwise be inexplicable. My sons noticed that in one room in which the pavement had sagged very little, there was an unusually small amount of overlying mould. 218 BURIAL OF THE REMAINS Chap. IV As tlie foundations of the walls generally He at a considerable depth, they will either have not subsided at all through the under- mining action of worms, or they will have subsided much less than the floor. This latter result would follow from worms not often working deep down beneath the founda- tions ; but more especially from the walls not yielding when penetrated by worms, whereas the successively formed burrows in a mass of earth, equal to one of the walls in depth and thickness, would have collapsed many times since the desertion of the ruins, and would consequently have shrunk or subsided. As the walls cannot have sunk much or at all, the immediately adjoining pavement from adhering to them will have been prevented from subsiding ; and thus the present curvature of the pavement is intelligible. The circumstance which has surprised me most with respect to Silehester is that during the many centuries which have elapsed since the old buildings were deserted, the vegetable mould has not accumulated over them to a greater thickness than that here observed. In Chap. IV. OF ANCIENT BUILDINGS. 219 most places it is only about 9 inches in thick- ness, but in some places 12 or even more inches. In Fig. 11, it is given as 20 inches, but this section was drawn by Mr. Joyce before his attention was particularly called to this subject. The land enclosed within the old walls is described as sloping slightly to the south ; but there are parts which, accord- ing to Mr. Joyce, are nearly level, and it appears that the mould is here generally thicker than elsewhere. The surface slopes in other pai'ts from west to east, and Mr. Joyce describes one floor as covered at the western end by rubbish and mould to a thickness of 28^ inches, and at the eastern end by a thickness of only 11^ inches. A very slight slope suffices to cause recent castings to flow downwards during heavy rain, and thus much earth will ultimately reach the neighbouring rills and streams and be carried away. By this means, the absence of very thick beds of mould over these ancient ruins may, as ] believe, be explained. Moreover most of the J and here has long been ploughed, and this would greatly aid the washing away of the finer earth during rainy weather. 220 BURIAL OF THE REMAINS Chap. I^*. The nature of tbe beds immediately beneath the vegetable mould in some of the sections is rather perplexing. We see, for instance, in the section of an excavation in a grass meadow (Fig. 14), which sloped from north to south at an angle of 3° 40', that the mould on the upper side is only six inches and on the lower side nine inches in thick- ness. But this mould lies on a mass (2 5 J inches in thickness on the upper side) " of '' dark brown mould," as described by Mr. Joyce, " thickly interspersed with small " pebbles and bits of tiles, which present a " corroded or worn appearance." The state of this dark-coloured earth is like that of a field which has long been ploughed, for the earth thus becomes intermingled with stones and fragments of all kinds which have been much exposed to the weather. If during the course of many centuries this grass meadow and the other now cultivated fields have been at times ploughed, and at other times left as pasture, the nature of the ground in the above section is rendered intelligible. For worms will continually have brought up fine earth from below, which will have been stirred Ceap. 1Y. of ancient BUILDINGS. 221 up by the plough whenever the land was cultivated. But after a time a greater thickness of fine earth will thus have been accumulated than could be reached by the plough; and a bed like the 25^-inch mass, in Fig. 14, will have been formed beneath the superficial mould, which latter will have been brought to the surface within more recent times, and have been well sifted by the worms. JVroxeter, Shropshire. — The old Roman city of Uriconium was founded in the early part of the second century, if not before this date ; and it was destroyed, according to Mr. Wright, probably between the middle of the fourth and fifth century. The inhabitants were massacred, and skeletons of women were found in the hypocausts. Before the year 1859, the sole remnant of the city above ground, was a portion of a massive wall about 20 ft. in height. The surrounding land undulates slightly, and has long been under cultivation. It had been noticed that the corn-crops ripened prematurely in certain narrow lines, and that the snow remained un- melted in certain places longer than in others 222 BURIAL OF THE REMAINS Chap. IV. These appearances led, as I was informed, to extensive excavations being undertaken. The foundations of many large buildings and several streets have thus been exposed to view. The space enclosed within the old walls is an irregular oval, about 1| mile in length. Many of the stones or bricks used in the buildings must have been carried away ; but the hyjDocausts, baths, and other underground buildings were found tolerably perfect, being filled with stones, broken tiles, rubbish and soil. The old floors of various rooms were covered with rubble. As I was anxious to know how thick the mantle of mould and rubbish was, which had so long concealed these ruins, I applied to Dr. H. Johnson, who had superintended tlie excavations ; and he, with the greatest kindness, twice visited the place to examine it in reference to ray ques- tions, and had many trenches dug in four fields which had hitherto been undisturbed. The results of his observations are given in the following Table. He also sent me speci- mens of the mould, and answered, as far ay he could, all my questions. Chap. IV. OF ANCIENT BUILDINGS. 223 Measurements by Dr. H. Johnson of the thickness of the vegetable mould over the roman ruins at Wroxeteu. Trenches dug in a field called " Old Works." Thlcknf^ss of mould in inches. 1. At a depth of 36 inches undisturbed sand was reached .. .. .. .. .. 20 2. At a depth of 33 inches concrete was reached 21 o. „ „ 9 inches concrete was reached 9 Trenches dug in a field called '^Shop "Leasows ;" this is the highest field within the old walls, and slopes down from a sub-central [^oint on all sides at about an angle of 2°. Thickness of mould in inches. 4. Summit of field, trench 45 inches deep .. 40 5. Close to summit of field, trench 36 inches deep 26 6. „ „ trench 28 inches deep 28 7. Near summit of field, trench 36 inches deep 24 8. „ „ trench at one end 89 inches deep ; the mould here graduated into tho underlying undisturbed sand, and its thickness is somewhat arbitrary. At the other end of the trench, a causeway was en- countered at a depth of only 7 inches, and the mould was here only 7 inches thick .. 24 9. Trench close to the last, 28 inches in depth .. 15 iO Lower part of same field, trench 30 inches deep 15 11 „ „ trench 31 inches deep 17 12. „ „ trench 36 inches deep, at which depth undisturbed sand was reached 28 221 BUKIAL OF THE REMAINS Chap. IV Thickneg«i of mould in Inches. 13. In another part of same field, trench 9.^ inches deep, stopped by concrete .. .. ., 9 2 14. In another part of same field, trench 9 inches deep, stopped by concrete .. .. .. 9 15. In another part of the same field, trench 24 inches deep, when sand was reached .. 16 16. In another part of same field, trench 30 inches deep, when stones were reached ; at one end of the trench mould 12 inches, at the other end 14 inches thick .. .. .. ..13 Small field between "Old Works" and *' Shop Leasows," I believe nearly as high as the upper part of the latter field. Thickness of mould in inches. 17. Trench 26 inches deep .. .. .. 24 18. „ 10 inches deep, and then came U]ion a causeway .. .. .. .. ..10 19. Trench 34 inches deep .. .. , .. 30 20. „ 31 inches deep ' .. 31 Field on the western side of the space enclosed within the old walls. Thickness of mould in inches 21. Trench 28 inches deep, when undisturbed sand w^as reached .. .. .. .. .. 16 22. Trench 29 inches deep, when undisturbed sand was reached .. .. .. .. ..15 23. Trench 14 inches dee}>, and then came upon j* building ., .. .. ., ..14 Dr. Johnson distinguished as mould the earth which differed, more or less abruptly, in Chap. IV. OF ANCIENT BUILDINGS. 225 its dark colour and in its texture from the underlying sand or rubble. In the specimens sent to me, the mould resembled that which lies immediately beneath the turf in old pasture-land, excepting that it often contained small stones, too large to have passed through the bodies of worms. But the trenches above described were dug in fields, none of which were in pasture, and all had been long- cultivated. Bearing in mind the remarks made in reference to Silchester on the effects of long-continued culture, combined with the action of worms in bringing up the finer particles to the surface, the mould, as so designated by Dr. Johnson, seems fairly well to deserve its name. Its thickness, where there was no causeway, floor or walls beneath, was greater than has been elsewhere ob- served, namely in many places above 2 ft., and in one spot above 3 ft. The mould was thickest on and close to the nearly level sum- mit of the field called " Shop Leasows," and in a small adjoining field, which, as I believe, is of nearly the same height. One side of the former field slopes at an angle of rather above 2°, and I should have expected that 226 BURIAL OF THE REMAINS Chap. IV the mould, from being washed down during heavy rain, would have been thicker in the lower than in the upper part; but this was not the case in two out of the three trenches here dug. In many places, where streets ran beneatV the surface, or where old buildings stood, the mould was only 8 inches in thickness; and Dr. Johnson was surprised that in ploughing the land, the ruins had never been struck by the plough as far as he had heard. He thinks that when the land was first cultivated the old walls were perhaps intentionally pulled down, and that hollow places were filled up. This may have been the case ; but if after the desertion of the city the land was left for many centuries uncultivated, worms would have brought up enough fine earth to have covered the ruins completely ; that is it they had subsided from having been under- mined. The foundations of some of the walls, for instance those of the portion still stand- ing about 20 feet above the ground, and those of the market-place, lie at the extra- ordinary depth of 14 feet; but it is highly improbable that the foundations were o^ener- Chap. IV. OP ANCIENT BUILDINGS. 227 ally SO deep. The mortar employed in the buildings must have been excellent, for it is still in parts extremely hard. Where- ever walls of any height have been exposed to view, they are, as Dr. Johnson believes, still perpendicular. The walls with such deep foundations cannot have been under- mined by worms, and therefore cannot have subsided, as appears to have occurred at Abinger and Silchester. Hence it is very difficult to account for their being now com- pletely covered with earth; but how much of this covering consists of vegetable mould and how much of rubble I do not know. The market-place, with the foundations at a depth of 14 feet, was covered up, as Dr. Johnson believes, by between 6 and 24 inches of earth. The tops of the broken-down walls of a caldarium or bath, 9 feet in depth, were likewise covered up with nearly 2 feet of earth. The summit of an arch, leading into an ash-pit 7 feet in depth, was covered up with not more than 8 inches of earth. When- ever a building which has not subsided is covered with earth, w^e must suppose, either that the upper layers of stone have been at 228 BUKIAL OF THE EEMAINS Chap. IV. some time carried away by man, or that earth has since been washed down during heavy rain, or blown down during storms, from the adjoining laud ; and this would be especially apt to occur where the land has long been cultivated. In the above cases the adjoining land is some^vhat higher than the three speci- fied sites, as far as I can judge by maps and from information given me by Dr. Johnson. If, however, a great pile of broken stones mortar, plaster, timber and ashes fell over the remains of any building, their disintegration in the course of time, and the sifting action of wormSj would ultimately conceal the whole beneath fine earth. Conclusion. — The cases given in this chapter show that worms have played a considerable part in the burial and concealment of several Roman and other old buildings in England ; but no doubt the washing down of soil from the neighbouring higher lands, and the de- position of dust, have together aided largely in the work of concealment. Dust would be apt to accumulate wherever old broken-down walls projected a little above the then exist- Chap. IV. OF ANCIENT BUILDINGS. 229 ing surface and thus afforded some shelter. The floors of the old rooms, halls and passages have generally sunk, partly from the settling of the ground, but chiefly from having been undermined by worms; and the sinking has commonly been greater in the middle than near the walls. The walls themselves, when- ever their foundations do not lie at a great depth, have been penetrated and undermined by worms, and have consequently subsided. The unequal subsidence thus caused, probably explains the great cracks which may be seen in many ancient walls, as well as their inclination from the perpendicular. liJO DISINTEGRATION Chap. V. CHAPTER Y. THE ACTION OF WORMS IN^ THE DExVUDATION OF THE LAND. Evidence of the amount of denudation which the land has undergone — Subaerial denudation — The depo^ition of dust — Vegetable mould, its dark colour and fine texture largely due to the action of worms — The disintegration of rocks by the humus-acids — Similar acids apparently generated within the bodies of worms — The action of these acids facilitated by the continued movement of the particles of earth — A thick bed of mould checks the disintegration of the underlying soil and rocks. Particles of stone worn or triturated in the gizzards ot worms — Swallowed stones serve as mill-stones— The levi- gated state of the castings — Fragments of brick in the castings over ancient buildings well rounded. The triturating power of worms not quite insignificant under a geological point of view. No one doubts that our world at one time consisted of crystalline rocks, and that it is to their disintegration through the action of air, water, changes of temperature, rivers, waves of the sea, earthquakes and volcanic outbursts, that we owe our sedimentary formations. These after being consolidated and sometimes Chap. Y. AND DENUDATION. 231 recrystalllzed, have often been again dis- integrated. Denudation means the removal of such disinteo^rated matter to a lower level. Of the many striking results due to the modern progress of geology there are hardly any more striking than those which relate to denudation. It was long ago seen that there must have been an immense amount of denudation ; but until the successive forma- tions were carefully mapped and measured, no one fully realised how great was the amount. One of the first and most remark- able memoirs ever published on this subject was that by Ramsay,* who in 1846 showed that in Wales from 9000 to 11,000 feet in thickness o'' solid rock had been stripped of! large tracks of country. Perhaps the plainest evidence of great denudation is afforded by faults or. cracks, which extend for many miles across certain districts, with the strata on one side raised even ten thousand feet above the corresponding strata on the opposite side ; and yet there is not a vestige of this gigantic displacement visible on the surface of the * " On the denudation of South Wales," &c., ' Memoirs of tha Geological Survey of Great Britain,' vol. i., p. 297, 1846. 1(} 2o2 DISINTEGEATION Cuap. V land. A huge pile of rock has been planed away on one side and not a remnant left. Until the last twenty or thirty years, most geologists thought that the waves of the sea were the chief agents in the work of denuda- tion ; but we may now feel sure that air and rain, aided by streams and rivers, are much more powerful agents, — that is if we consider the whole area of the land. The long lines of escarpment which stretch across several parts of England were formerly considered to be undoubtedly ancient coast-lines ; but we now know that they stand u|) above the general surface merely from resisting air, rain and frost better than the adjoining formations. It has rarely been the good fortune of a geologist to bring conviction to the minds of his fellow-workers on a disputed point by a single memoir; but Mr. Whitaker, of the Geological Survey of England, was so for- tunate when, in 1867, he published his paper '' On sub-aerial Denudation, and on Cliffs and Escarpments of the Chalk." * Before thi.s * ' Geological Magazine,' October and November, 1867, vol. Iv. pp. 447 and 483. Copious references on the subject are giv,.a in tiiis remarkal)le memoir. Chap. V. AND DENUDATION. 233 paper appeared, Mr. A. Tylor had adduced important evidence on sub-aerial denudation, by showing that the amount of matter brought down by rivers must infaUibly low^er the level of their drainage-basins by many feet in no immense lapse of time. This line of argument has since been foUov^^ed up in the most interesting manner by Archibald Geikie, Croll and others, in a series of valuable memoirs.* For the sake of those who have never attended to this subject, a single instance may be here given, namely that of the Mississippi, which is chosen because the amount of sediment brought down by this great river has been investigated with especial care by order of the United States Govern- ment. The result is, as Mr. Croll shows, that the mean level of its enormous area of * A. Tylor " On changes of the sea-level," &c., ' Philosophical Mag.' (Ser. 4th) vol. v., 1853, p. 258. Archibald Geikie, Transactions Greolog. Soc. of Glasgow, vol. iii., p. 153 (read March, 1868). Croll "On Geologicaf Time," 'Philosophical Mag.', May, August, and November, 18G8. See also Croll, ' Climate and Time,' 1875, Chap. XX. For some recent information on ihe amount of sediment brought down by rivers, see * Nature,' Sept. 23rd, 1880. Mr. T. Mellard Peade has published some interesting articles on the astonishing amount of matter brought down in solution by rivers. See Address, Gcolog. Soc., Liverpool, 187G-77. 234 DISINTEGRATION Chap. V drainage must be lowered ^sVe ^^ ^ ^^'^^ annaally, or 1 foot in 4566 years. Con- sequently, taking the best estimate of the mean height of the North American continent, viz. 748 feet, and looking to the future, the whole of the great Mississippi basin will be washed away, and '' brought down to the sea- ^' level in less than 4,500,000 years, if no " elevation of the land takes place." Some rivers carry down much more sediment re- latively to their size, and some much less than the Mississippi. Disintegrated matter is carried away by the wind as well as by running water During volcanic outbursts much rock is triturated and is thus widely dispersed ; and in all arid countries the wind plays an im- portant part in the removal of such matter. Wind-driven sand also wears down the hardest rocks. I have shown * that during four months of the year a large quantity of dust is blown from the north-western shores of Africa, and falls on the Atlantic over a * '* An account of the fine dust which often fcills on Vessels in the Atlantic Ocean," Proc. Gee log. Soc. of London, Jime 4ih, lb45. Chap. V. AND DENUDATION. 235 space of 1600 miles in latitude, and for a distance of from 300 to 600 miles from the coast. But dust has been seen to fall at a distance of 1030 miles from the shores of Africa. During a stay of three weeks at St. Jago in the Cape Verde Archipelago, the atmosphere was almost always hazy, and ex- tremely fine dust coming from Africa was con- tinually falling. In some of this dust which fell in the open ocean at a distance of between 330 and 380 miles from the African coast, there were many particles of stone, about y^Q-o of an inch square. Nearer to the coast the water has been seen to be so much discoloured by the falling dust, that a sailing vessel left a track behind her. In countries, like the Cape Yerde Archipelago, where it seldom rains and there are no frosts, the solid rock never- theless disintegrates ; and in conformity with the views lately advanced by a distinguished Belgian geologist, De Koninck, such disin- tegration may be attributed in chief part to the action of the carbonic and nitric acids, together with the nitrates and nitrites of ammonia, dissolved in the dew. In all humid, even moderately humid, 23G DISINTEGEATION Chap. V. countries, worms aid in the work of denuda- tion in several ways. The vegetable mould which covers, as with a mantle, the surface of the Land, has all passed many times through their bodies. Mould differs in ap- pearance from the subsoil only in its dark colour, and in the absence of fragments or particles of stone (when such are present in the subsoil), larger than those which can pass through the alimentary canal of a worm. This sifting of the soil is aided, as has already been remarked, by burrowing animals of many kinds, especially by ants. In countries wdiere the summer is long and dry, the mould in protected places uiust be largely increased by dust blown from other and more exposed places. For instance, the quantity of dust sometimes blown over the plains of La Plata, where there are no solid rocks, is so great, that during the " gran seco," 1827 to 1830, the appearance of the land, which is here unenclosed, was so completely changed that the inhabitants could not recognise the limits of their own estates, and endless law- suits arose. Immense quantities of dust are likewise blov/n about in Egypt and in the Chap. Y. AND DENUDATION. 237 south of France. In China, as Richthofen maintains, beds appearing like fine sediment, several hundred feet in thickness and extend- ing over an enormous area, owe their origin to dust blown from the high lands of central Asia.* In humid countries like Great Britain, as long as the land remains in its natural state clothed with vegetation, the mould in any one place can hardly be much increased by dust ; but in its present con- dition^ the fields near high roads, where there is much traffic, must receive a considerable amount of dust, and when fields are harrowed during dry and windy weather, clouds of dust may be seen to be blown away. But in all these cases the surface-soil is merely trans- ported from one place to another. The dust which falls so thickly within our houses con- * For La Plata, see my * Journal of Eesearches,' during the TDyage of the Beagle, 1845, p. 133. !^lie de Beaumont has given (' Le9ons de Geolog. pratique,' torn. I, 1845, p. 183) an excellent account of the enormous quantity of dust which is transported in some countries. I cannot but think that Mr. Proctor has somewhat exaggerated (' Pleasant Ways in Science,' 1879, p. 379) the agency of dust in a humid country like Great Britain. James Geikie has given (' Prehistoric Europe,' 1880, p. 165) a full abstract of Richthofen's views, which, however, he disputes. 238 DISINTEGRATION Chap. Y sists largely of organic matter, and if spread over the land would in time decay and dis- appear almost entirely. It appears, however, from recent observations on the snow-fields of the Arctic rea-ions, that some Httle meteoric dust of extra mundane origin is continually falling. The dark colour of ordinary mould is obviously due to the presence of decaying organic matter, which, however, is present in but small quantities. The loss of weight which mould suffers when heated to redness seems to be in large part due to water in com- bination being dispelled. In one sample of fertile mould the amount of organic matter was ascertained to be only 1-76 per cent. ; in some artificially prepared soil it was as much as 5*5 per cent., and in the famous black soil ol Eussia from 5 to even 12 per cent.* In leaf- mould formed exclusively by the decay of leaves the amount is much greater, and in peat the carbon alone sometimes amounts to * These statements are taken from Von Hensen in * Zeitsclirift fiir wissenschaft. Zoologie,' Bd. xxviii., 1877, p. 360. Those with respect to peat are taken from Mr. A. A. Julien in * Proc American Assoc. Science, 1879, p. 314. Chap. Y. AND DENUDATION. 239 64 per cent. ; but with tliese latter cases we are not here concerned. The carbon in the soil tends gradually to oxidise and to dis- appear, except where water accumulates and the climate is cool ; * so that in tlie oldest pasture-land there is no great excess of organic matter, notwithstanding the con- tinued decay of the roots and the underground stems of plants, and the occasional addition of manure. The disappearance of the organic matter from mould is probably much aided by its being brought again and again to the surface in the castings of worms. Worms, on the other hand, add largely to the organic matter in the soil by the astonish- ing number of half-decayed leaves which they draw into their burrows to a depth of 2 or 3 inches. They do this chiefly for obtain- ing food, but partly for closing the mouths of their burrows and for lining the upper part. The leaves which they consume are moistened, torn into small shreds, partially digested^ and intimately commingled with * I have given some facts on the climate necessary or favour- able for the formation of peat, in my ' Journal of Researches, 1845, p. 287. 240 DISINTEGKATION Chap. Y. earth ; and it is this process ^hich gives to vegetable mould its uniform dark tint. It is known that various kinds of acids are gen- erated by the decay of vegetable matter ; and fiom the contents of the intestines of worms and from their castings being acid, it seems pro- bable that the process of digestion induces an analogous chemical change in the swallowed, triturated, and half decayed leaves. The large quantity of carbonate of lime secreted by the calciferous glands apparently serves to neutra- lise the acids thus generated ;' for the digestive fluid of worms will not act unless it be alkaline. As the contents of the upper part of their in- testines are acid, the acidity can hardly be due to the presence of uric acid.* We may there- fore conclude that the acids in the alimentary canal of w^orms are formed during the diges- tive process ; and that probably they are nearly of the same nature as those in ordinary humus. The latter are Avell known to have the power of de-oxidising or dissolving per- oxide of iron, as may be seen wherever peat overlies red sand, or where a rotten root penetrates such sand. Now I kept some woims in a pot filled with very fine reddish Chap. V. AND DEN UDATION. . 241 sand, consisting of minute particles of silex coated with the red oxide of iron ; and the burrows, which the worms made through this sand, were lined or coated in the usual manner with their castings, formed of the sand mingled with their intestinal secretions and the refuse of the digested leaves; and this sand had almost wholly lost its red colour. When small portions of it were placed under the microscope, most of the grains were seen to be transparent and colourless, owing to the dissolution of the oxide; whilst almost all the grains taken from other parts of the pot were coated with the oxide. Acetic acid produced hardly any effect on this sand ; and even hydrochloric, nitric and sulphuric acids, diluted as in the Pharmacopoeia^ produced less effect than did the acids in the intestines of the worms. Mr. A. A. Julien has lately collected all the extant information about the acids gen- erated in humus, which, according to some chemists, amount to more than a dozen different kinds. These acids, as well as their acid salts (i.e., in combination with potash, Boda, and ammonia), act energetically on 212 DISINTEGRATION Chap. V, carbonate of lime and on the oxides of iron. It is, also, known that some of these acids, which were called lons^ ago by Thenard azo- humic, are enabled to dissolve colloid silica in proportion to the nitrogen which they contain.* In the formation of these latter acids worms probably afford some aid, for Dr. H. Johnson informs me that by Nessler's test he found 0*018 per cent, of ammonia in their castings. The several humus-acids, which appear, as we have just seen, to be generated within the bodies of worms during the digestive process, and their acid salts, play a highly important part, according to the recent observations of Mr. Julien, in the disintegration of various kinds of rocks. It has long been known that the carbonic acid, and no doubt nitric and nitrous acids, which are present in rain-water, act in like manner. There is, also, a great excess of carbonic acid in all soils, especially in rich soils, and this is dissolved by the water * A. A. Julieu " On the Geological action of the Humus-acids," ' Proc. American Assoc. Science,' vol. xxviii., 1879, p. 311. Aho on " Chemical erosion on Mountain Summits ;" ' New York Academy of Sciences,' Oct. 14, 1878, as quoted in the 'American Katuralist.' See also, on this subject, S. W. Johnson, '* How Crops Feed," 1870, p. 138 Chap. V. AND DENUDATION, 243 in the ground. The living roots of plantS; moreover, as Saclis and others have shown, quickly corrode and leave their impressions on polished slabs of marble, dolomite and phosphate of lime. They will attack even basalt and sandstone.* But we are not hero concerned with agencies which are wholly independent of the action of worms. The combination of any acid with a base is much facilitated by agitation, as fresh surfaces are thus continually brought into contact. This will be thoroughly effected with the particles of stone and earth in the intestines of worms, during the digestive pi'o- cess ; and it should be remembered that tho entire mass of the mould over every field, passes, in the course of a few years, through their alimentary canals. Moreover as the old burrows slowly collapse, and as fresh castings are continually brought to the surface, the whole superficial layer of mould slowly re- volves or circulates ; and the friction of the particles one with another will rub off the finest films of disintegrated matter as soon aa * See, for references on this subject, S. W. Johnson, " How Crops Feed," 1870, p. 326. 244 DISINTEGRATION Chap. V. they are formed. Througli these several means, minute fragments of rocks of many kinds and mere particles in the soil will be continually exposed to chemical decomposi- tion ; and thus the amount of soil will tend to increase. As worms line their burrows with their castings, and as the burrows penetrate to a depth of 5 or 6, or even more feet, some small amount of the humus-acids will be carried far down, and will there act on the underlying rocks and fragments of rock. Thus the thickness of the soil, if none be re- moved from the surface, w^ill steadily though slowly tend to increase ; but the accumulation will after a time delay the disintegration of the underlying rocks and of the more deeply seated particles. For the humus-acids which are generated chiefly in the upper layer of vegetable mould, are extremely unstable com- pounds, and are liable to decomposition before they reach any considerable depth.* A thick bed of overlying soil will also check the downward extension of great fluctuations of temperature, and in cold countries will check • This statement is taken from Mr, Julien, ' Pioc. American Assoc. Science ' vol. xxviii., 1879, p. 330. Chap. Y. AND DENUDATION. 2 15 tlie powerful action of frost. TLe free access of air will likewise be excluded. From those several causes disintegration would be almost arrested, if the overlying mould were to increase much in thickness, owing to none or little being removed from the surface.* In my own immediate neighbourhood we have a curious proof how effectually a few feet of clay checks some change which goes on in flints, lying freely exposed ; for the large ones which have lain for some time on the surface of ploughed fields cannot be used for building; they will not cleave properly and are said by the workmen to be rotten, f It is * The preservative power of a layer of mould and turf is often stcwTi by the perfect state of the glacial scratches on rocks when first uncovered. Mr. J. Geikie maintains, in his last very inter- esting work (' Prehistoric Europe,' 1881), that the more perfect scratches are probably due to the last access of cold and increase of ice, during the long-continued, intermittent glacial period. f Many geologists have felt much surprise at the complete disappearance of flints over wide and nearly level areas, from \vhich the chalk has been removed by subaerial denudation. But the surface of every flint is coated by an opaque modified layer, which will just yield to a steel point, whilst the freshly- fractured, translucent surface will not thus yield. The re- moval by atmospheric agencies of the outer modified surfaces of freely exposed flints, though no doubt excessively slow, to- gether with the modification travelling inwards, will, as may Vq suspected, ultimately lead to their complete disintegration, not- withstanding that they appear to be so extremely durable. 246 DISINTEGRATION Chap. V. therefore necessary to obtain flints for build- ing purposes from the bed of red clay over- lying the chalk (the residue of its dissolution by rainwater) or from the chalk itself. Not only do worms aid indirectly in the chemical disintegration of rocks, but there is good reason to believe that they likewise act in a direct and mechanical manner on the smaller particles. All the species which swallow earth are furnished with gizzards ; and these are lined with so thick a chitinous membrane, that Perrier speaks of it,* as ^' une veritable armature." The gizzard is sur- rounded by powerful transverse muscles, which, according to Claparede, are about ten times as thick as the longitudinal ones ; and Perrier saw them contracting energetically. Worms belonging to one genus, Digaster, have two distinct but quite similar gizzards ; and in another genus, Moniligaster, the second gizzard consists of four pouches, one succeeding the other, so that it may almost be said to have five gizzards.f In the same • ' Archives de Zoolog. exper.' torn. iii. 1874, p. 409. t ' Nouvelles Archives du Museum,' torn. viii. 1872, p. 95| 131. Chap. V. AND DENUDATION. 247 manner as gallinaceous and strufchious birds swallow stones to aid in the trituration of their food, so it appears to be with terricolous worms. The gizzards of thirty-eight of our common worms were opened, and in twenty- five of them small stones or grains of sand, sometimes together with the hard calcareous concretions formed within the anterior cal- ciferous glands, were found, and in two others concretions alone. In the gizzards of the remaining worms there were no stones ; but some of these were not real exceptions, a? the gizzards were opened late in the autumn when the worms had ceased to feed and theii gizzards were quite empty.* When worms make their burrows through earth abounding with little stones, no doubt many will be unavoidably swallowed ; but it must not be supposed that this fact accounts for the frequency with which stones and sand are found in their gizzards. For beads of glass and fragments of brick and of hard tiles were scattered over the surface * Morren, in speaking of the earth in the alimentary canals oi worms, says, " praesepfe cum lapillis commixtam vidi ; " * De Lumbrici terrestris,' &c., 1829, p. 16. ir 248 DISINTEGRATION Cuap. V. of the earth, in pots in which worms were kept and had already made their burrows ; and very many of these beads and fragments were picked np and swallowed by the worms, for they were found in their castings, intes- tines, and gizzards. They even swallowed the coarse red dust, formed by the pounding of the tiles. Nor can it be supposed thai they mistook the beads and fragments for food ; for we have seen that their taste is delicate enough to distinguish between dif- ferent kinds of leaves. It is therefore manifest that they swallow hard objects, such as bits of stone, beads of glass and angular fragments of bricks or tiles for some special purpose ; and it can hardly be doubted that this is to aid their gizzards in crushing and grinding the earth, which they so largely consume. That such hard objects are not necessary for crushing leaves, may be inferred from the fact that certain species, which live in mud or water and feed on dead or living vegetable matter, but which do not swallow earth, are not provided with gizzards,* and • Perrier, ' Archives de Zoolog. exper.' torn. iii. 1874, p. 419, CiiAr. V. AND DENUDATION. 249 therefore cannot have the poAver of utilising stones. During the grinding process, the particles of earth must he ruhbed against one another, and between the stones and the tough lining membrane of the gizzard. The softer particles will thus suffer some attrition, and will perhaps even be crushed. This con- clusion is supported by the appearance of freshly ejected castings, for these often re- minded me of the appearance of paint which has just been ground by a workman between two flat stones. Morren remarks that the intestinal canal is '' impleta tenuissima terra, veluti in pulverem redacta." * Perrier also speaks of " I'etat de pate excessivement fine a laquelle est reduite la terre qu'ils rejettent," &c.t As the amount of trituration which the particles of earth undergo in the gizzards of worms possesses some interest (as we shall hereafter see), I endeavoured to obtain evidence on this head by carefully examining many of the fragments which had passed * Morren, * De Lumbrici terrestris,' &c., p. 1 6. X ' Archives de Zoolog. Expdr.' torn. iii. 1874, p. 418. 250 DISINTEGKATION CnAr. V. through their alimentary canals. With worms living in a state of nature, it is of CDurse impossible to know how much the fragments may have been worn before they were swallowed. It is, however, clear that worms do not habitually select already rounded particles, for sharply angular bits of flint and of other hard rocks were often found in their gizzards or intestines. On three occasions sharp spines from the stems of rose-bushes were thus found. Worms kept in confinement repeatedly swallowed angular fragments of hard tile, coal, cinders, and even the sharpest fragments of glass. Gallinaceous and struthious birds retain the same stones in their gizzards for a long time, which thus become well rounded ; but this does not appear to be the case with worms, judging from the large number of the fragments of tiles, glass beads, stones, &c., commonly found in their castings and intestines. So that unless the same fragments were to pass re- peatedly through their gizzards, visible signs of attrition in the fragments could hardly be expected, except perhaps in the case of very soft stones. Chap. V. AND DENUDATION. 25 1 I will now give such evidence of attrition as I have been able to collect. In the gizzards of some worms dug out of a thin bed of mould over the chalk, there were many well- rounded small fragments of chalk, and two fragments of the shells of a land-mollusc (as ascertained by their microscopical structure), which latter were not only rounded but somewhat polished. The calcareous concre- tions formed in the calciferous glands, which are often found in their gizzards, intestines, and occasionally in their castings, when of large size, sometimes appeared to have been rounded; but with all calcareous bodies the rounded appearance may be partly or wholly due to their corrosion by carbonic acid and the humus-acids. In the gizzards of several worms collected in my kitchen garden near a hothouse, eight little frag- ments of cinders were found, and of these, six appeared more or less rounded, as were twc bits of brick; but some other bits were not at all rounded. A farm-road near Abinger Hall had been covered seven years before with brick-rubbish to the depth of about 6 inches ; turf had grown over this 252 DISINTEGRx\TION Chap. V. rubbish on both sides of the road for a width of 18 inches, and on this turf there were innumerable castings. Some of them were coloured of a uniform red owing to the presence of much brick-dust, and they contained many particles of brick and of hard mortar from 1 to 3 mm. in diameter, most of which were plainly rounded ; but all these particles may have been rounded before they were protected by the turf and were swallowed, like those on the bare parts of the road which were much worn. A hole in a pasture-field had been filled up with brick-rubbish at the same time^ viz., seven years ago, and was now covered with turf; and here the castings contained very many particles of brick, all more or less rounded ; and this brick-rubbish, after being shot into the hole, could not have undergone any attrition. Again, old bricks very little broken, together with fragments of mortar, w^ere laid down to form walks, and were then covered with from 4 to 6 inches of gravel ; six little fragments of brick were extracted from castings collected on these walks, three of which were plainly worn. CiiAP. Y. AND DENUDATION. 253 There were also very many particles of hard mortar, about half of which were w^ell rounded; and it is not credible that these could have suffered so much corrosion from the action of carbonic acid in the course of only seven years. Much better evidence of the attrition of hard objects in the gizzards of worms, is afforded by the state of the small fragments of tiles or bricks, and of concrete in the castings thrown up where ancient buildings once stood. As all the mould covering a field passes every few years through the bodies of worms, the same small fragments will probably be swallowed and brought to the surface many times in the course of cen- turies. It should be premised that in tlie several following cases, the finer matter was first washed away from the castings, and then all the particles of bricks, tiles and con- crete were collected without any selection, and were afterwards examined. Now in the cast- ings ejected between the tesseras on one of the buried floors of the Roman villa at Abinger, there were many particles (from | to 2 ram. in diameter) of tiles and concrete, which it 254 DISINTEGKATION Chap. Y. was impossible to look at with the naked eye or through a strong lens, and doubt for a moment that they had almost all undergone much attrition. I speak thus after having examined small water-worn pebbles, formed from Roman bricks, which M. Henri do Saussure had the kindness to send me, and which he had extracted from sand and gravel beds, deposited on the shores of the Lake of Geneva, at a former period when the water stood at about two metres above its present level. The smallest of these water- worn pebbles of brick from Geneva resembled closely many of those extracted from the gizzards of worms, but the larger ones were somewhat smoother. Four castings found on the recently un- covered, tesselated floor of the great room in the Roman villa at Brading, contained many particles of tile or brick, of mortar, and of hard white cement ; and the majority of these appeared plainly worn. The particles of mortar, however, seemed to have suffered more corrosion than attrition, for grains of si lex often projected from their surfaces. Castings from within the nave of Beaulieu Chap. V. AND DENUDATION. 255 Abbey, which was destroyed by Henry YIIl., were collected from a level expanse of turf, overlying the buried tesselated pavement, tlirough which worm-burrows passed ; and these castings contained innumerable particles of tiles and bricks, of concrete and cement, the majority of which had manifestly under- gone some or much attrition. There were also many minute flakes of a micaceous slate, the points of which were rounded. If the above supposition, that in all these cases the same minute fragments have passed several times through the gizzards of worms, be rejected, notwithstanding its inherent probability, we must then assume that in all the above cases the many rounded fragments found in the castings had all accidentally undergone much attrition before they were swallowed ; and this is highly improbable. On the other hand it must be stated that fragments of ornamental tiles, somewhat harder than common tiles or bricks, which had been swallowed only once by worms kept in confinement, were with the doubtful ex- ception of one or two of the smallest grains, not at all rounded. Nevertheless some of 2dQ disintegration Chap. V. them appeared a little worn, though not rounded. Notwithstanding these cases, if we consider the evidence above given, there can be little doubt that the fragments, which serve as millstones in the gizzards of worms, suffer, when of a not very hard texture, some amount of attrition ; and that the smaller particles in the earth, which is habitually swallowed in such astonishingly large quantities by worms, are ground together and are thus levigated. If this be the case, the ^' terra tenuissima," — the "pate excessivement fine," — of which the castings largely consist, is in part due to the mechanical action of the gizzard ; * and this fine matter, as we shall see in the next chapter, is that which is chiefly washed away from the innumerable castings on every field during each heavy shower of rain. If the softer stones yield at all, the harder ones will suffer some slight amount of wear and tear. * This conclusion reminds me of the vast amount of extremely fino chalky mud which is found within the lagoons of many atolls, where the sea is tranquil and waves cannot triturate the blocks of coral. This mud must, as I believe (' The Structure and Distribution of Coral-Eeefs,' 2nd edit. 1874, p. 19), be attributed to the innumerable annelids and other animals which burrow into the dead coral, and to the fishes, Holothurians, &c., which browse on th(! living corals. Chap. Y. AND DENUDATION. 257 The trituration of small particles of stone in the gizzards of worms is of more import- ance under a geological point of view than may at first appear to be the case ; for Mr. Sorby has clearly shown that the ordinary means of disintegration, namely running water and the weaves of the sea, act with less and less power on fragments of rock the smaller they are. " Hence," as he remarks, *' even making no allowance foi" the extra " buoying up of very minute particles by a " current of water, depending on surface '' cohesion, the effects of wearing on the form '' of the grains must vary directly as their *' diameter or thereabouts. If so, a grain ^^ ''of an inch in diameter would be worn ten " times as much as one ^^ of an inch in " diameter, and at least a hundred times as *' much as one xoVo ^^ ^^ ^^^^ ^'^ diameter. " Perhaps, then, we may conclude that a " grain -f^ of an inch in diameter would be '^ worn as much or more in drifting a mile as *' a grain y^Vo ^^' ^'^ ^^^^^^ ^'^ being drifted ** 1 00 miles. On the same principle a pebble *' one inch in diameter would be worn re- " latively more hj being drifted only a few 258 DISINTEGRATION, ETC. Chap. V. ** hundred yards."* Nor should we forget, in considering the power which worms exert in triturating particles of rock, that there is good evidence that on each acre of land, which is sufficiently damp and not too sandy, gravelly or rocky for worms to inhahit, a weight of more than ten tons of earth annually passes through their bodies and is brought to the surface. The result for a country of the size of Great Britain, within a period not very long in a geological sense, such as a million years, cannot be insignificant ; for the ten tons of earth has to be multiplied first by the above number of years, and then by the number ot acres fully stocked with worms ; and in England, together with Scotland, the land which is cultivated and is v/ell fitted for these animals, has been estimated at above 32 million acres. The product is 320 million million tons of earth. * Anniversary Address : ' The Quarterly Journal of the Geological Soc' May 1880, p. 50. CHAPTER YI. THE DENUDATION OF THE LAND — Continued, Denudation aided by recently ejected castings flowing down inclined grass-covered surfaces — The amount of earth which annually flows downwards — The effect of tropical rain on worm castings — The finest particles of earth washed com- pletely away from castings — The disintegration of dried cast- ings into pellets, and their rolling down inclined surfaces — The formation of little ledges on hill-sides, in part due to the accumulation of disintegrated castings — Castings blown to leeward over level land — An attempt to estimate the amount thus blown — The degradation of ancient encampments and tumuli — The preservation of the crowns and furrows on land anciently ploughed — The formation and amount of mould over the Chalk formation. We are now prepared to consider the more direct part which worms take in the denuda- tion of the land. When reflecting on sub- aerial denudation, it formerly appeared to me, as it has to others, that a nearly level or very gently inclined surface, covered with turf, could suffer no loss during even a long lapse of time. It may, however, be urged that at long intervals, debacles of rain or 260 DE>sUDATION OF THE LAND Chap. YI water- spouts would remove all tlie mould from a very gentle slope ; but when ex- amining the steep, turf-covered slopes in Glen Roy, I was struck with the fact how rarely any such event could have happened since the Glacial period, as Avas plain from the well-preserved state of the three successive ^' roads " or lake-margins. But the difficulty in believing that earth in any appreciable quantity can be removed from a gently in- clined surface, covered with vegetation and matted with roots, is removed through the agency of worms. For the many castings which are thrown up during rain, and those thrown up some little time before heavy rain, flow for a short distance down an inclined surface. Moreover much of the finest levi- gated earth is washed completely away from the castings. During dry weather castings often disintegrate into small rounded pellets, and these from their weight often roll down any slope. This is more especially apt tv'^ occur when they are started by the wind, and probably wdien started by the touch of an animal, liowever small. "We shall also see that a strong wind blows all the castings, Chap. YI. AIDED BY WOEMS. 261 even on a level field, to leeward, whilst they are soft; and in like manner the pellets when they are dry. If the wind blows in nearly the direction of an inclined surface, the flowing down of the castings is much aided. The observations on which these several statements are founded must now be given in some detail. Castings when first ejected are viscid and soft ; during rain, at which time worms apparently prefer to eject them, they are still softer ; so that I have sometimes thought that worms must swallow much water at such times. However this may Le, rain, even when not very heavy, if long continued, renders recently-ejected castings semi-fluid ; and on level ground they then spread out into thin, circular, flat discs, exactly as would so much honey or very soft mortar^ with all traces of their vermiform structure lost. This latter fact was sometimes made evident, when a worm had subsequently bored through a flat circular disc of this kind, and heaped up a fresh vermiform mass in the centre. These flat subsided discs have been repeatedly seen hj 262 DENUDATION OF THE LAND Chap. VL me after heavy rain, in many places on land of all kinds. On the flowing of wet castings, and the rolling of dry disintegrated eastings down inclined surfaces,-— Wh^xi castings are ejected on an inclined surface during or shortly before heavy rain, they cannot fail to flow a little down the slope. Thus, on some steep slopes in Knowle Park^ which were covered with coarse grass and had apparently existed in this state from time immemorial, I found (Oct. 22, 1872) after several wet days that almost all the many castings were con- siderably elongated in the line of the slope ; and that they now consisted of smooth^ only shghtly conical masses. Whenever the mouths of the burrows could be found from which the earth had been ejected, there was more earth below than above them. After come heavy storms of rain (Jan. 25, 1872) two rather steeply inclined fields near Down, which had formerly been ploughed and were now rather sparsely clothed with poor grass, were visited, and many castings extended down the slopes for a length of 5 inches, which was twice or thrice the usual diameter Chap. VI. AIDED BY WORMS. 263 of the castings thrown up on the level parts of these same fields. On some fine grassy slopes in Holwood Park, inclined at angles oetween 8"^ and 1 1"^ 30' with the horizon, where the surface apparently had never been disturbed by the hand of man, castings abounded in extraordinary numbers ; and a space 16 inches in length transversely to the slope and 6 inches in the line of the slope, was completely coated, between the blades of grass, with a uniform sheet of confluent and subsided castings. Here also in many places the castings had flowed down the slope, and now formed smooth narrow patches of earth, 6, 7, and 7^ inches in length. Some of these consisted of two castings, one above the other, which had become so completely confluent that they could hardly be distinguished. On my lawn, clothed with very fine grass, most of the castings are black, but some are yellowish from earth having been brought up from a greater depth than usual, and the fowing-down of these yellow castings after heavy rain, could be clearly seen where the slope was 5° ; and where it was less than 1*^ gome evidence of their flowing down could 18 264 DENUDATION OF THE LAND Chap. YL still be detected. On another occasion, after rain which was never heavy, but which lasted for 18 hours, all the castings on this samo gentl};^ inclined lawn had lost their vermiform structure ; and they had flowed, so that fully two-thirds of the ejected earth lay below the mouths of the burrows. These observations led me to make others with more care. Eight castings were found on my lawn, where the grass-blades are fine and close together, and three others on a field with coarse grass. The inclination of the surface at the eleven places where these castings were collected varied between 4"^ 30' and 17° 30'; the mean of the eleven inclinations being 9° 26'. The length of tlie castings in the direction of the slope was first measured with as much accuracy as their irregularities would permit. It was found possible to make these measurements within about ^ of an inch, but one of the castings was too irregular to admit of measurement. The average length in the direction of the slope of the remaining ten castings was 2*03 inches. The castings were then divided with a knife into two parts along a horizontal line passing through the mouth Chap. YL AIDED BY WOEMS. 265 of tlie bnrrow, wliicli was discovered by slicing oiF the turf; and all the ejected earth was separately collected, namely the part above the hole and the part below. Afterwards these two parts were weighed. In every case there was much more earth below than above ; the mean weight of that above being 103 grains, and of that below 205 grains ; so that the latter was very nearly double the former. As on level ground castings are commonly thrown np almost equally round the mouths of the burrows, this difference in weight indicates the amount of ejected earth which had flowed down the slope. But very many more observations would be requisite to arrive at any general result ; for the nature of the vegetation and other accidental circumstances, such as the heaviness of the rain, the direction and force of the wind, &c., appear to be more important in determining the quantity of the earth which flows down a slope than its angle. Thus with four castings on my lawn (included in the above eleven) where the mean slope was 7° 19', the difference in the amount of earth above and below the burrows was greater than with three other 266 DENUDATION OF THE LAND Chap. VL castings on the same lawn where the mean slope was 12° 5'. We may, however, take the above eleven eases, which are accurate as far as they go, and calculate the weight of the ejected earth which annually flows down a slope having a mean inclination of 9° 26'. This was done hy my son George. It has been shown that almost exactly two-thirds of the ejected earth is found below the mouth of the burrow and one-third above it. Now if the two-thirds which is below the hole be divided into two equal parts, the upper half of this two-thirds exactly counterbalances the one- third which is above the hole, so that as far as regards the one-thiid above and the upper half of the two-thirds below, there is no flow of earth down the hill-side. The earth con- stituting the lower half of the two-thirds is, however, displaced through distances which are different for every part of it, but which may be represented by the distance between the middle point of the lower half of the two-thirds and the hole. So that the average distance of displacement is a half of the whole length of the worm -casting. Now the Chap. VI. AIDED BY WOEMS. 267 average length of ten out of the above eleven castings was 2*03 inches, and half of this we may take as being one inch. It may therefore be concluded that one-third of the whole earth brought to the surface was in these cases carried down the slope through one inch. It was shown in the third chapter that on Leith Hill Common, dry earth weighing at least 7*453 lbs. was brought up by worms to the surface on a square yard in the course of a year. If a square yard be drawn on a hill-side with two of its sides horizontal, then it is clear that only -^ part of the earth brought up on that square yard would be near enough to its lower side to cross it, supposing the displacement of the earth to be through one inch. But it appears that only -J of the earth brought up can be con- sidered to flow downwards ; hence -g- of -g^ or -j-^8 of 7*453 lbs. will cross the lower side of our square yard in a year. Now -^ww ^^ 7*453 lbs. is 1*1 oz. Therefore 1"I oz. of dry earth will annually cross each linear yard run- ning horizontally along a slope having the above inclination ; or very nearly 7 lbs. will 268 DENUDATION OF THE LAND Chap. VL annually cross a horizontal line, 100 yards in length, on a hill-side having this iDclination. A more accurate, though still very rough, calculation can be made of the bulk of earth, which in its natural damp state annually flows down the same slope over a yard-line drawn horizontally across it. From the several cases given in the third chapter, it is known that the castings annually brought to the surface on a square yard, if uniformly spread out would form a layer *2 of an inch in thickness : it therefo] e follows by a calculation similar to the one already given, that -J- of '2 X 36^ or 2*4 cubic inches of damp earth will annually cross a horizontal line one yard in length on a hill-side with the above inclination. This bulk of damp castings was found to weigh 1*85 oz. Therefore 11*56 lbs. of damp earth, instead of 7 lbs. of dry earth as by the former calculation, would annually cross a line 100 yards in Isngth on our inclined surface. In these calculations it has been assumed that the castings flow a short distance down- wards during the whole year, but this occurs only with those ejected during or shortly CuAP. VI. AIDED BY WORMS. 269 before rain ; so that the above results are thus far exaggerated. On the other hand, during rain much of the finest earth is washed to a considerable distance from the castings, even where the slope is an ex- tremely gentle one, and is thus wholly lost as far as the above calculations are concerned. Castings ejected during dry weather and which have set hard, lose in the same manner a considerable quantity of fine earth. Dried castings, moreover, are apt to disinte- grate into little pellets, which often roll or are blown down any inclined surface. There- fore the above result, namely that 2*4 cubic inches of earth (weighing 1-85 oz. whilst damp) annually crosses a yard-line of the specified kind, is probably not much if at all exaggerated. This amount is small ; but we should bear in mind how many branching valleys inter- sect most countries, the whole length of which must be very great ; and that earth is steadily travelling down both turf-covered sides of each valley. For every 100 yards in length in a valley with sides sloping as in the foregoing cases, 480 cubic inches of damp 270 DENUDATION OF THE LAND Chap. YI. earth, weighing above 23 pounds, will annually reach the bottom. Here a thick bed of alluvium will accumulate, ready to be washed away in the course of centuries, as the stream in the middle meanders from side to side. If it could be shown that worms generally excavate their burrows at right angles to an inclined surface, and this would be their shortest course for bringing up earth from beneath, then as the old burrows col- lapsed from the weight of the superincum- bent soil, the collapsing would inevitably cause the whole bed of vegetable mould to sink or slide slowly down the inclined sur- face. But to ascertain the direction of many burrows was found too difficult and trouble- some. A straight piece of wire was, how- ever, pushed into twenty-five burrows on several sloping fields, and in eight cases the burrows were nearly at right angles to the slope ; whilst in the remaining cases they were indifferently directed at various angles, either upwards or downwards with respect to the slope. In countries where the rain is very heavy, Chap. VI. AIDED BY WORMS. 271 as in the tropics, the castings appear, ag might have heen expected, to be washed down in a greater degree than in England. Mr. Scott informs me that near Calcutta the tall columnar castings (previously described), the diameter of which is usually between i and IJ inch, subside on a level surface, after heavy rain, into almost circular, thin, flat discs, between 3 and 4 and sometimes 5 inches in diameter. Three fresh castings, which had been ejected in the Botanic Gardens " on a slightly inclined, grass- '* covered, artificial bank of loamy clay," were carefully measured, and had a mean height of 2*17, and a mean diameter of 1'43 inches ; these after heavy rain, formed elongated patches of earth, with a mean length in the direction of the slope of 5-83 inches. As the earth had spread very little up the slope, a large part, judging from the original diameter of these castings, must have flowed bodily downwards about 4 inches. Moreover some of the finest earth of which they were com- posed must have been washed completely away to a still greater distance. In drier sites near Calcutta, a species of worm ejects 272 DENUDATION OF THE LAND Chap. VL its castings, not in vermiform masses, but in little pellets of varying sizes : these are very numerous in some places, and Mr. Scott says that they " are washed away by every " shower." I was led to believe that a considerable quantity of fine earth is washed quite away from castings during rain, from the surfaces of old ones being often studded with coarse particles. Accordingly a little fine precipi- tated chalk, moistened with saliva or gum- water, so as to be slightly viscid and of the same consistence as a fresh casting, was placed on the summits of several castings and gently mixed with them. These castings were then watered through a very fine rose, the drops from which were closer together than those of rain, but not nearly so large as those in a thunder storm ; nor did they strike the ground with nearly so much force as drops during heavy rain. A casting ihus treated subsided with surprising slowness, owing as I suppose to its viscidity. It did not fiow bodily down the grass-covered sur- face of the lawn, which was here inclined at an angle of 16° 20',* nevertheless many par- Chap. VI. AIDED BY WORMS. 273 tides of the chalk were found three inches below the casting. The experiment was re- peated on three other castings on different parts of the lawn, which sloped at 2° 30', 3° and 6°; and particles of chalk could be seen between 4 and 5 inches below the cast- ing ; and after the surface had become dry, particles were found in two cases at a distance of 5 and 6 inches. Several other castings with precipitated chalk placed on their summits were left to the natural action of the rain. In one case, after rain which was not heavy, the casting was longitudinally streaked with white. In two other cases the surface of the ground was rendered some- what white for a distance of one inch from the casting ; and some soil collected at a dis- tance of 2~ inches, where the slope was 7°_, effervesced slightly when j)laced in acid. After one or two weeks, the chalk was wholly? or almost wholly washed away from all the castings on which it had been placed, and these had recovered their natural colour. It may be here remarked that after very heavy rain shallow pools may be seen on level or nearly level fields, where the soil is not 274 DENUDATION OF THE LAND Chap. YI. very porous, and the water in them is often slightly muddy ; when such little pools have dried, the leaves and hlades of grass at their bottoms are generally coated with a thin layer of mud. This mud I believe is derived in large part from recently ejected castings. Dr. King informs me that the majority of the before described gigantic castings, which he found on a fully exposed, bare, gravelly knoll on the Nilgiri Mountains in India, had been more or less weathered by the previous north-east monsoon ; and most of them pre- sented a subsided appearance. The worms here eject their castings only during the rainy season ; and at the time of Dr. King's visit no rain had fallen for 110 days. He carefully examined the ground between the place where these huge castings lay, and a little water-course at the base of the knoll, and nowhere was there any accumulation of fine earth, such as would necessarily have been left by the disintegration of the castings if they had not been wholly removed. He Ihei'ofore has no hesitation in asserting that the whole of these huge castings are annually washed during the two monsoons (when CiiAP. VI. AIDED BY WORMS. 275 about 100 inches of rain fall) into the little water-course, and thence into the plains lying below at a depth of 3000 or 4000 feet. Castings ejected before or during dry weather become hard, sometimes surprisingly hard^ from the particles of earth having been cemented together by the intestinal secre- tions. Frost seems to be less effective in their disintegration than might have been expected. Nevertheless they readily disin- tegrate into small pellets, after being alter- nately moistened with rain and again dried. Those which have flowed during rain down a slope, disintegrate in the same manner. Such pellets often roll a little down any sloping surface ; their descent being sometimes much aided by the wind. The whole bottom of a broad dry ditch in my grounds, where there were very few fresh castings, was completely covered with these pellets or disintegrated castings, which had rolled down the steep sides, inclined at an angle of 27°. Near Nice, in places where the great cylin- drical castings, previously described, abound, the soil consists of very fine arenaceo-cal- careous loam ; and Dr. King informs me that 276 DENUDATION OF THE LAND Chap. YI. these castings are extremely liable to crumble during dry weather into small fragments^ which are soon acted on by rain, and then sink down so as to be no longer distinguisli* able from the surrounding soil. He sent me a mass of such disintegrated castings, collected on the top of a bank, where none could have rolled down from above. They must have been ejected within the previous five or six months, but they now consisted of more or less rounded fragments of all sizes, from |- of an inch in diameter to minute grains and mere dust. Dr. King witnessed the crumbling process whilst drying some perfect castings, which he afterwards sent me. Mr. Scott also remarks on the crumbling of the castings near Calcutta and on the mountains of Sikkim during the hot and dry season. When the castings near Nice had been ejected on an inclined surface, the disinteg- rated fragments rolled downwards, without losing their distinctive shape ; and in som« places could " be collected in basketfuls." Dr. King observed a striking instance of this fact on the Corniche road, where a drain, about 2^ feet wide and 9 inches deep, had been made Chap. Y1. AIDED BY WOEMS. 277 to catch tlie surface drainage from the adjoin- ing hill-side. The bottom of this drain was covered for a distance of several hundred yarc's, to a depth of from 1^ to 3 inches, by a layer of broken castings, still retaining their characteristic shape. Nearly all these in- numerable fragments had rolled down from above, for extremely few castings had been ejected in the drain itself. The hill-side was steep, but varied much in inclination, which Dr. King estimated at from 30^ to 60° with the horizon. He climbed up the slope, and " found every here and there little embank- " ments, formed by fragments of the castings " that had been arrested in their downward " progress by irregularities of the surface, "by stones, twigs, &c. One little group of '' plants of Anemone hortensis had acted in this " manner, and quite a small bank of soil had "collected round it. Much of this soil had "crumbled down, but a great deal of it still " retained the form of castings." Dr. King dug up this plant, and was struck with the thickness of the soil which must have recently accumulated over the crown of the rhizoma, as shown by the length of the 278 DENUDATION TO LAND Chap. \L bleached petioles, in comparison with those of other plants of the same kind, where there had been no such accumulation. The earth thus accumulated had no doubt been secured (as I have everywhere seen) by the smaller roots of the plants. After describing this and other analogous cases, Dr. King con- cludes : " I can have no doubt that worms " help greatly in the process of denudation." Ledges of earth on steep hill-sides. — Little horizontal ledges, one above another, have been observed on steep grassy slopes in many parts of the world. Their formation has been attributed to animals travelling repeatedly along the slope in the same horizontal lines while grazing, and that they do thus move and use the ledges is certain ; but Professor Hens- low (a most careful observer) told Sir J. Hooker that he was convinced that this was not the sole cause of their formation. Sir J. Hooker saw such ledges on the Himalayan and Atlas ranges, where there were no domesticated animals and not many wild ones ; but these latter would, it is probable, use the ledges at flight while grazing like our domesticated nnimals, A friend observed for me the ledges Chap. YL LEDGES ON HILL-SIDES. 279 on the Alps of Switzerland, and states thai they ran at 3 or 4 ft. one above the other and were about a foot in breadth. They had been deeply pitted by the feet of grazing cows. Similar ledges were observed by the same friend on our Chalk downs, and on an old talus of chalk-fragments (thrown out of a quarry) which had become clothed with turf. My son Francis examined a Chalk escarp- ment near Lewes ; and here on a part which was very steep, sloping at 40° with the horizon, about 30 flat ledges extended hori- zontally for more than 100 yards, at an average distance of about 20 inches, one beneath the other. They were from 9 to 10 inches in breadth. When viewed from a distance they presented a striking appearance, owing to their parallelism ; but when examined closely, they were seen to be somewhat sinuous, and one often ran into another, giving the appearance of one ledge having forked into two. They are formed of light-coloured earth, which on Ihe outside, where thickest, was in one case 9 inches, and in another case between 6 and 7 inches in thickness. Above the ledges, the thickness of the earth over the chalk was in 19 280 DENUDATION TO LAND Chap. VL the former case 4 and in the latter only 3 inches. The grass grew more vigorously on the outer edges of the ledges than on any other part of the slope, and here formed a tufted fringe. Their middle part was bare, but whether this had been caused by the trampling of sheep, which sometimes frequent the ledges, my son could not ascertain. Nor could he feel sure how much of the earth on the middle and bare parts, consisted of disintegrated worm-castings which had rolled down from above; but he felt convinced that some had thus originated ; and it was manifest that the ledges with their grass-fringed edges would arrest any small object rolling down from above. At one end or side of the oank bearing these ledges, the surface consisted in parts of bare chalk, and here the ledges were very irregular. At the other end of the bank, the slope suddenly became less steep, and here the ledges ceased rather abruptly ; but little em- bankments only a foot or two in length were still present. The slope became steeper lower down the hill, and the regular ledges then re- appeared. Another of my sons observed, on Chap. YI. LEDGES ON HILL-SIDES. 281 the inland side of Beachy Head, where the surface sloped at about 25°, many short little embankments like those just mentioned. They extended horizontally and were from a few inches to two or three feet in length. They supported tufts of grass growing vigorously. The average thickness of the mould of which they were formed, taken from nine measurements, was 4' 5 inches; while that of the mould above and beneath them was on an average only 3*2 inches, and on each side, on the same level, 3'1 inches. On the upper parts of the slope, these em- bankments showed no signs of having been trampled on by sheep, but in the lower parts such signs were fairly plain. No long con- tinuous ledges had here been formed. If the little embankments above the Cor- niche road, which Dr. King saw in the act of formation by the accumulation of dis- integrated and rolled worm-castings, were to become confluent along horizontal lines, ledges would be formed. Each embankment would tend to extend laterally by the lateral extension of the arrested castings; and animals grazing on a steep slope would almost certainly make use 282 DENUDATION TO LAND Chap. Yl of every prominence at nearly the same level, and would indent the turf between them ; and such intermediate indentations would again arrest the castings. An irregular ledge when once formed would also tend to become more regular and horizontal by some of the castings rolling laterally from the higher to the lower parts, which would thus be raised. Any pro- jection beneath a ledge would not afterwards receive distintegrated matter from above, and would tend to be obliterated by rain and other atmospheric agencies. There is some analogy between the formation, as here sup- posed, of these ledges, and that of the ripples of wind-drifted sand as described by Lyell.* The steep, grass-covered sides of a mountainous valley in Westmoreland, called G-risedale, was marked in many places with innumerable, almost horizontal, little ledges, or rather lines of miniature cliffs. Their formation was in no way connected with the action of worms, for castings could not any- wiiere be seen (and their absence is an inexplicable fact) although the turf lay in many places over a considerable thickness of * ' Elements of Geology,' 18G5, p. 20 Chap. YI. LEDGES ON HILL-SIDES. 283 boulder-clay and moraine rubbish. Nor, as far as I could judge, was the formation of these little cliffs at all closely connected with the trampling of cows or sheep> It appeared as if the whole superficial, somewhat argil- laceous earth, while partially held together by the roots of the grasses, had slided a little way down the mountain sides ; and in thus sliding, had yielded and cracked in horizontal lines, transversely to the slope. Castings blown to leevjard by the wind, — We have seen that moist castings flow, and that disintegrated castings roll down any inclined surface ; and we shall now see that castings, recently ejected on level grass-covered surfaces, are blown during gales of wind ac- companied by rain to leeward. This has been observed by me many times on many fields during several successive years. After such gales, the castings present a gently inclined and smooth, or sometimes furrowed, surface to windward, while they are steeply inclined or precipitous to leeward, so that they resem- ble on a miniature scale glacier-groimd hillocks of rock. They are often cavernous on the 284- DENUDATION OF THE LAND. Chap. VL leeward side, from the upper part having curled over the lower part. During one un- usually heavy south-west gale with torrents of rain, many castings were wholly blown to leeward, so that the mouths of the burrows were left naked and exposed on the windward side. Eecent castings naturally flow down an inclined surface, but on a grassy field, which sloped between 10° and 15°, several were found after a heavy gale blown up the slope. This likewise occurred on another occasion on a part of my lawn where the slope was somewhat less. On a third occasion, the castings on the steep, grass-covered sides of a valley, down which a gale had blown, were directed obliquely instead of straight down the slope ; and this was obviously due to the combined action of the wind and gravity. Four castings on my lawn, where the downward inclination was 0° 45', 1°, 3° and 3° 30' (mean 2° 45') towards the north-cast, after a heavy south-west gale with rain, were divided across the mouths of the burrows and weighed in the manner formerly described. The mean weight of the earth below the mouths of burrows and to leeward, was to that Chap. YI. CASTINGS BLOWN TO LEEWAKD. 2S5 above tlie nQOuths and on the windward side as 2| to 1 ; whereas we have seen that with several castings which had flowed down slopes having a mean inchnation of 9° 26', and with three castings where the inclination was above 12°, the proportional weight of the earth below to that above the burrows was as only 2 to 1. These several cases show how efficiently gales of wind accompanied by rain act in displacing recently-ejected castings. We may therefore conclude that even a moderately strong wind will produce some slight effect on them. Dry and indurated castings, after their dis- integration into small fragments or pellets, are sometimes, probably often, blown by a strong wind to leeward. Thk was observed on four occasions, but I did not sufficiently attend to this point. One old casting on a gently slop- ing bank was blown quite away by a strong south-west wind. Dr. King believes that the wind removes the greater part of the old crumbling castings near Nice. Several old castings on my lawn were marked with pins and protected from any disturbance. They were examined after an interval of 10 286 DENUDATION OF THE LAND. Chap. YI, weeks, duriog wbicli time the weather had been alternately dry and rainy. Some, which were of a yellowish colour had been washed almost completely away, as could be seen by the colour of the surrounding ground. Others had completely disappeared, and these no doubt had been blown away. Lastly, others still remained and would long remain, as blades of grass had grown through them. On poor pasture land, which has never been rolled and has not been much trampled on by animals, the whole surface is sometimes dotted with little pimples, through and on which grass grows ; and these pimples con- sist of old worm-castings. In all the many observed cases of soft cast- ings blown to leeward, this had been effected by strong winds accompanied by rain. As such winds in England generally blow from the south and south-west, earth must on the whole tend to travel over our fields in a north and north-east direction. This fact is interesting, because it might be thought that none could be removed from a level, grass- covered surface by any means. In thick and level woods, protected from the wind, castings Chap. VI. CASTINGS BLOWN TO LEEWAED. 287 will never be removed as long as tlie wood lasts ; and mould will here tend to accumulate to the depth at which worms can work, I tried to procure evidence as to how much mould is blown, whilst in the state of cast/- ings, by our wet southern gales to the north- east, over open and flat land, by looking to the level of the surface on opposite sides of old trees and hedge-rows ; but 1 failed owing to the unequal growth of the roots of trees and to most pasture-land having been formerly ploughed. On an open plain near Stonehenge, there exist shallow circular trenches, with a low embankment outside, surrounding level spaces 50 yards in diameter. These rings appear very ancient, and are believed to be contem poraneous with the Druidical stones. Castings ejected within these circular spaces, if blown to the north-east by south-west winds would form a layer of mould within the trench, thicker on the north-eastern than on any other side. But the site was not favourable for the action of worms, for the mould over the surrounding Chalk formation with flints, was only 3*37 inches in thickness, from a mean of 288 DENUDATION OF THE LAND. Chap. VL six observations made at a distance of 10 yards outside the embankment. The thickness of the mould within two of the circular trenches was measured every 5 yards all round, on the inner sides near the bottom. My son Horace protracted these measurements on paper ; and though the curved line representing the thick- ness of the mould was extremely irregular, yet in both diagrams it could be seen to be thicker on the north-eastern side than elsewhere. When a mean of all the measurements in both the trenches was laid down and the line smoothed, it was obvious that the mould was thickest in the quarter of the circle between nortli-west and north-east; and thinnest in the quarter between south-east and south- west, especially at this latter point. Besides the foregoing measurements, six others were taken near together in one of the circular trenches, on the north-east side ; and the mould here had a mean thickness of 2*29 inches ; while the mean of six other measure- ments on the south-west side was only 1*46 inches. These observations indicate that the castings had been blown by the south-west winds from the circular enclosed space into Chap. VI. CASTINGS BLOWN TO LEEWARD. 289 the trencli on the north-east side ; but many more measurements in other analogous cases would be requisite for a trustworthy result. The amount of fine earth brought to the surface under the form of castings, and after- wards transported by the winds accompanied by rain, or that which flows and rolls down an inclined surface, no doubt is small in the course of a few scores of years ; for otherwise all the inequalities in our pasture fields Tvould be smoothed within a much shorter period than appears to be the case. But the amount which is thus transported in the course of thousands of years cannot fail to be consider- able and deserves attention. E. de Beaumont looks at the vegetable mould which every- where covers the land as a fixed line or zero, from which the amount of denudation may be measured.* He ignores the continued formation of fresh mould by the disintegra- tion of the underlying rocks and fragments of rock ; and it is curious to find how much more philosophical were the views, main- * " Lecons de Geologie pratique, 1845 ; cinqiiieme Le9on. All Elie de Beaumont's arguments are admirably controverted by Prof. A. Geikie in his essay in Transact. Geolog. Soc. of Glasgow, vol. iii. p. 153, 1868. 290 DENUDATION OF THE LAND. Chap. VL tallied long ago, by Playfair, who, in 1802, wrote, *' in the permanence of a coat of '' vegetable mould on the surface of the earth, " we have a demonstrative proof of the con- " tinned destruction of the rocks."* Ancient encampments and tumuli, — E. de Beaumont adduces the present state of many ancient encampments and tumuli and of old ploughed fields, as evidence that the surface of the land undergoes hardly any degradation. But It does not appear that he ever examined the thickness of the mould over different parts of such old remains. He relies chiefly on indirect, but apparently trustworthy, evi- dence that the slopes of the old embankments are the same as they originally were ; and it is obvious that he could know nothing about their original heights. In Knole Park a mound had been thrown up behind the rifle- targets, which appeared to have been formed of earth originally supported by square blocks of turf. The sides sloped, as nearly as I could estimate them, at an angle of 45° or 50° with the horizon, and they were covered, especially on the northern side, with long coarse grass, • 'Illustrations of the Iluttonian Theory of the Earth/ p. 107, CiiAi'. YI. ANCIENT MOUNDS. 291 beneath which many worm-castings were found. These had flowed bodily downwards^ and others had rolled down as pellets. Hence it is certain that as long as a mound of thia kind is tenanted by worms, its height will be continually lowered. The fine earth which flows or rolls down the sides of such a mound accumulates at its base in the form of a talus. A bed, even a very thin bed, of fine earth is eminently favourable for worms ; so that a greater Dumber of castings would tend to be ejected on a talus thus formed than elsewhere : and these would be partially washed away by every heavy shower and be spread over the adjoining level ground. The final result would be the lowering of the whole mound, whilst the inclination of the sides would not be greatly lessened. The same result would assuredly follow with ancient embankments and tumuli ; except where they had been formed of gravel or of nearly pure sand, as such matter is unfavourable for worms. Many old fortifications and tumuli are believed to be at least 2000 years old ; and we should bear in mind that in many places about one inch of mould is brought to the surface in 5 years or 292 DENUDATION OF THE LAND. Chap. VL two inches in 10 years. Therefore in so long a period as 2000 years, a large amount of earth will have been repeatedly brought to the surface on most old embankments and tumuli, especially on the talus round their bases, and much of this earth will have been washed completely away. We may therefore conclude that all ancient mounds, when not formed of materials unfavourable to worms, will have been somewhat lowered in the course of centuries, although their inclina- tions may not have been greatly changed. Fields formerly ploughed, — From a very remote period and in many countries, land has been ploughed, so that convex beds, called crowns or ridges, usually about 8 feet across and separated by furrows, have been thrown up. The furrows are directed so as to carry off the surface water. In my attempts to ascertain how long a time these crowns and furrows last, when ploughed land has been converted into pasture, obstacles of many kinds were encountered. It is rarely known when a field was last ploughed ; and some fields which were thought to have been in pasture from time immemorial were after Chap. VI. ANCIENTLY PLOUGHED FIELDS. 293 wards discovered to have been ploughed only 50 or 60 years before. During the early part of the present century, when the price of corn was very high, land of all kinds seema to have been ploughed in Britain. There is, however, no reason to doubt that in many eases the old crowns and furrows have been preserved from a very ancient period.* That they should have been preserved for very unequal lengths of time would naturally follow from the crowns, when first thrown up, having differed much in height in dif- ferent districts, as is now the case with recently ploughed land. In old pasture fields, the mould, wherever measurements were made, was found to be from i to 2 inches thicker in the furrows than * Mr. E. Tylor in his Presidential address ('Jouraal of the Anthropological Institute,' May 1880, p. 451) remarks: "It appears from several papers of the Berlin Society as to tho German 'high-fields' or 'heathen-fields* (Eochacker, and Heidenacker) that they correspond much in their situation on hills and wastes with the ' elf-furrows ' of Scotland, which popular mythology accounts for by the story of the fields having been put under a Papal interdict, so that people took to cultivating the hills. There seems reason to suppose that, like the tilled plots in the Swedish forests which tradition ascribes to the Did ' hackers,* the German heathen-fields represent tillage by an ancient and barbaric population." 294 DENUDATION OF TEE LAND. Chap. VI on tlie crowns ; but this would naturally follow from the finer earth having been washed from the crowns into the furrows before the land was well clothed with turf; and it is impossible to tell what part worms may have played in the work. Nevertheless from what we have seen, castings would certainly tend to flow and to be washed during heavy rain from the crowns into the furrows. But as soon as a bed of fine earth had by any means been accumulated in the furrows, it would be more favourable for worms than the other parts, and a greater number of castings would be thrown up here than elsewhere ; and as the furrows on sloping land are usually directed so as to carry off the surface water, some of the finest earth would be washed from the castings which had been here ejected and be carried completely away. The result would be that the furrows would be filled up very slowly, while the crowns would be lowered perhaps still more slowly by the flowing and rolling of the castings down their gentle inclinations into the furrows. Nevertheless it might be expected that old furrows, especially those on a sloping surface, Chap. VI. ANCIENTLY PLOUGHED FIELDS. 295 would in the course of time be filled up and disappear. Some careful observers, however, who examined fields for me in Grloucestershire and Staffordshire, could not detect any dif- ference in the state of the furrows in the upper and lower parts of sloping fields, sup- posed to have been long in pasture ; and they came to the conclusion that the crowns and furrows would last for an almost endless number of centuries. On the other hand the process of obliteration seems to have com- menced in some places. Thus in a grass field in North Wales, known to have been ploughed about 65 years ago, which sloped at an angle of 15° to the north-east, the depth of the furrows (only 7 feet apart) was care- fully measured, and was found to be about 4^ inches in the upper part of the slope, and only 1 inch near the base, where they could be traced with difficulty. On another field sloping at about the same angle to the south- west, the furrows were scarcely perceptible in the lower part ; although these same furrows when followed on to some adjoining level ground were from 2^ to 3^ inches in depth. A third and closely similar case was 20 296 DEi^UDATION OF THE LAND. Chap. YI. observed. In a fourth case, the mould in a furrow in the upper part of a sloping field was 2^ inches, and in the lower part 4| inches in thickness. On the Chalk Downs at about a mile dis- tance from Stonehenge, my son William ex- amined a grass-covered, furrowed surface, sloping at from 8° to 10°, which an old shep- herd said had not been ploughed within the memory of man. The depth of one furrow was measured at 16 points in a length of 68 paces, and was found to be deeper where the slope was greatest and where less earth would naturally tend to accumulate, and at the base it almost disappeared. The thickness of the mould in this furrow in the upper part was 2^ inches, which increased to 5 inches a little aboA^e the steepest part of the slope ; and at the base, in the middle of the narrow valley, at a point which the furrow if con- tinued would have struck, it amounted to 7 inches. On the opposite side of the valley, there were very faint, almost obliterated, traces of furrows. Another analogous but not so decided a case was observed at a few miles distance from Stonehenge. On the Chap. Y1. MOULD OYER TEE CHALK. 297 whole it appears that the crowns and fur- rows on land formerly ploughed, but now covered with grass, tend slowly to disappear when the surface is inclined ; and this is pro- bably in large part due to the action of worms ; but that the crowns and furrows last for a very long time when the surface is nearly level. Formation and amount of mould over the Chalk Formation, — Worm-castings are often ejected in extraordinary numbers on steep, grass-covered slopes, where the Chalk comes close to the surface, as my son William observed near Winchester and elsewhere. If such castings are largely washed away during heavy rains, it is difficult to understand at first how any mould can still remain on our Downs, as there does not appear any evident means for supplying the loss. There is, more- ovei, another cause of loss, namely in the per- colation of the finer particles of earth into the fissures in the chalk and into the chalk itself. These considerations led me to doubt for a timo whether I had not exaggerated the amount of fine earth which flows or rolls down grass- covered slopes under the form of castings ; and 298 DENUDATION OF THE LAND. Chap. VI. I sougbt for additional information. In some places, the castings on Chalk Downs consist largely of calcareous matter, and here the supply is of course unlimited. But in other places, for instance on a part of Teg Down near Winchester, the castings were all black and did not effervesce with acids. The mould over the chalk was here only from 3 to 4 inches in thickness. So again on the plain near Stonehenge, the mould, apparently free from calcareous matter, averaged rather less than 3^ inches in thickness. "Why worms should penetrate and bring up chalk in some places and not in others I do not know. In many districts where the land is nearly level, a bed several feet in thickness of red clay full of unworn flints overlies the Upper Chalk. This overlying matter, the surface of which has been converted into mould, con sists of the undissolved residue from the chalk. It mav be well here to recall the case of the fragments of chalk buried beneath worm- castings on one of my fields, the angles of which were so completely rounded in the course of 29 years that the fragments now resembled water-worn pebbles. This musl Chap. VL MOULD OVER THE CHALK. 299 have been effected by the carbonic acid in the rain and in the ground, by the humus- acids, and by the corroding power of living roots.* Why a thick mass of residue has not been left on the Chalk, wherever the land is nearly level, may perhaps be accounted for by the percolation of the fine particles into the fissures, which are often present in the chalk and are either open or are filled up with impure chalk, or into the solid chalk itself. That such percolation occurs can hardly be doubted. My son collected some powdered and fragmentary chalk beneath the turf near Winchester ; the former was found by Colonel Parsons, R.E., to contain 10 per cent., and the fragments 8 per cent, of earthy matter. On the flanks of the escarpment near Abinger in Surrey, some chalk close beneath a layer of flints, 2 inches in thickness and covered by 8 inches of mould, yielded a re- sidue of 3 '7 per cent, of earthy matter. On the other hand the Upper Chalk properly contains, as I was informed by the late David Forbes who had made many analyses, only from 1 to 2 per cent, of earthy matter ; and two samples from pits near my house con- 300 DENUDATION OF THE LAND. Chap. VI tained 1*3 and 0*6 per cent. I mention these latter cases because, from the thickness of the overlying bed of red clay with flints, I had imagined that the underlying chalk liiight here be less pure than elsewhere. The cause of the residue accumulating more in some places than in others, may be attributed to a layer of argillaceous matter having been left at an early period on the chalk, and this would check the subsequent percolation of earthy matter into it. From the facts now given we may conclude that castings ejected on our Chalk Downs suffer some loss by the percolation of their finer matter into the chalk. But such impure superficial chalk, when dissolved, would leave a larger supply of earthy matter to be added to the mould than in the case of pure chalk. Besides the loss caused by percola- tion, some fine earth is certainly washed down the sloping grass-covered surfaces of our Downs. The washing-down process, how- ever, will be checked in the course of time ; for although I do not know how thin a layer of mould suffices to support worms, yet a limit must at last be reached ; and then their cast- Chap. YI. MOULD OYEK THE CHALK. 301 ings would cease to be ejected or would become scanty. The following cases show that a consider- able quantity of fine earth is washed down The thickness of the mould was measured ai points 12 yards apart across a small valley in the Chalk near Winchester. The sides sloped gently at first ; then became inclined at about 20° ; then more gently to near the bottom, wdiich transversely was almost level and about 50 yards across. In the bottom, the mean thickness of the mould from five measurements was 83 inches; whilst on the sides of the valley, where the inclination varied between 14° and 20°, its mean thick- ness was rather less than 3*5 inches. As the turf-covered bottom of the valley sloped at an angle of only between 2° and 3°, it is probable that most of the 8*3-inch layer of mould had been washed down from the fianks of the valley, and not from the upper part. But as a shepherd said that he had seen water flow- ing in this valley after the sudden thawing of snow, it is possible that some earth may have been broTight down from the upper part ; or, on the other hand, that some may have been 302 DENUDATION OF THE LAND. Chap. YI. carried further down the valley. Closely similar results, with respect to the thickness of the mould, were obtained in a neighbouring valley. St. Catherine's Hill, near Winchester, is 827 feet in height, and consists of a steep cone of chalk about i of a mile in diameter. The upper part was converted by the Romans, or, as some think, by the ancient Britons, into an encampment, by the excavation of a deep and broad ditch all round it. Most of the chalk removed during the work was thrown upwards, by which a projecting bank was formed ; and this effectually prevents worm- castings (which are numerous in parts), stones, and other objects from being washed or rolled into the ditch. The mould on the upper and fortified part of the hill was found to be in most places only from 2^ to 3^ inches in thickness ; whereas it had accumulated at the foot of the embankment above the ditch to a thickness in most places of from 8 to 9^ iiiches. On the embankment itself the mould was only 1 to l^ inch in thickness; and within the ditch at the bottom it varied from 2|- to 3|, but was in one spot 6 inches in Chap. VI. MOULD OVEK THE CHALK. 303, thickness. On the north-west side of the hill, either no embankment had ever been thrown up above the ditch, or it had subse- quently been removed ; so that here there was nothing to prevent worm-castings, earth and stones being washed into the ditch, at the bottom of which the mould formed a layer from 11 to 22 inches in thickness. It should however be stated that here and on other parts of the slope, the bed of mould often con- tained fragments of chalk and flint which had obviously rolled down at different times from above. The interstices in the under- lying fragmentary chalk were also filled up with mould. My son examined the surface of this hill to its base in a south-west direction. Beneath the great ditch, where the slope was about 24°. the mould was very thin, namely from 1| to 2| inches; whilst near the base, where the slope was only 3° to 4°, it increased to between 8 and 9 inches in thickness. We may therefore conclude that on this artificially modified hill, as well as in the natural valleys of the neighbouring Chalk Downs, some fine earth, probably derived in large part from 304 DENUDATION OF THE LAND. Chap. VI. worm-castings, is washed down, and accumu- lates in the lower parts, notwithstanding the percolation of an unknown quantity into the underlying chalk ; a supply of fresh earthy matter being afforded by the dissolution Ox the chaJk through atmospheric and other agenoieis. CHAPTER YII. COXCLUSIOX. Summary of the part which worms have played in the history of the world — Their aid in the disintegration of rocks — In the denudation of the land — In the preservation of ancient remaina — In the preparation of the soil for the growth of plants — Mental powers of worms — Concljsion. Worms have played a more important part in the history of the world than most persons would at first suppose. In almost all humid countries they are extraordinarily numerous, and for their size possess great muscular power. In many parts of England a weight of more than ten tons (10,516 kilogrammes) of dry earth annually passes through their bodies and is brought to the surface on each acre of land ; so that the whole superficial bed of vegetable mould passes through their bodies in the course of every few years. From the collapsing of the old burrows the mould is in constant though slow movement, 306 CONCLUSION. Chap. VI and the particles composing it are thus rubbed together. By these means fresh sur- faces are continually exposed to the action of the carbonic acid in the soil, and of the humus-acids which appear to be still more efficient in the decomposition of rocks. The generation of the humus-acids is probably hastened during the digestion of the many half-decayed leaves which worms consume. Thus the particles of earth, forming the superficial mould, are subjected to conditions eminently favourable for their decomposition and disintegration. Moreover, the particles of the softer rocks suffer some amount of mechanical trituration in the muscular giz- zards of worms, in which small stones serve as mill-stones. The finely levigated castings, when brought to the surface in a moist condition, flow during rainy weather down any moderate slope ; and the smaller particles are washed far down even a gently inclined surface. Castings when dry often crumble into small pellets and these are apt to roll down any sloping surface. Where the land is quite level and is covered with herbage, and where tlio Chap. YII. CONCLUSION. 307 climate is humid so that much dust cannot be blown away it appears at first sight im- possible that there should be any appreciable amount of subaerial denudation ; but worm- castings are blown, especially whilst moist and viscid, in one uniform direction by the |.>revalent winds which are accompanied by rain. By these several means the superficial mould is prevented from accumulating to a great thickness ; and a thick bed of mould checks in many ways the disintegration of the underlying rocks and fragments of rock. The removal of worm castings by the above means leads to results which are far from insignificant. It has been shown that a layer of earth, '2 of an inch in thickness, is in many places annually brought to the surface per acre ; and if a small part of this amount flows, or rolls, or is washed, even for a short distance down every inclined surface, or is repeatedly blown in one direction, a great effect will be produced in the course of ages. It was found by measurements and calculations that on a surface with a mean inclination of 9° 26', 2*4 cubic inches of earth which had been ejected by worms crossed, in the course 308 CONCLUSION, Chap. VIL of a year, a liorizontal line one yard in length; so that 240 cubic inches would cross a line 100 yards in length. This latter amount in a damp state would weigh Hi pounds. Thus a considerable weight of earth is continually moving down each side of every valley, and will in time reach its bed. Finally this earth will be transported by the streams flowing in the valleys into the ocean, the great receptacle for all matter denuded from the land. It is known from the amount of sediment annually delivered into the sea by the Mississippi, that its enormous drainage-area must on an aver- age be lowered '00263 of an inch each year ; and this would suffice in four and half million years to lower the whole drainage-area to the level of the sea-shore. So that, if a small fraction of the layer of fine earth, '2 of an inch in thickness, which is annually brought to the surface by worms, is carried away, a great result cannot fail to be produced within a period which no geologist considers ex- tremely long. Archaeologists ought to be grateful to worms, as they protect and preserve for an Chap. VII. CONCLUSION. 309 indefinitely long period every object, not liable to decay, which is dropped on the surface of the land, by burying it beneath their castings. Thus, also, many elegant and curious tesselated pavements and other ancient remains have been preserved ; though no doubt the worms have in these cases been largely aided by earth washed and blown from the adjoining land, especially when cul- tivated. The old tesselated pavements have, however, often suffered by having subsided unequally from being unequally undermined by the worms. Even old massive walls may be undermined and subside ; and no building is in this respect safe, unless the foundations lie 6 or 7 feet beneath the surface, at a depth at which worms cannot work. It is probable that many monoliths and some old walls have fallen down from having been undermined by worms. Worms prepare the ground in an excellent manner for the growth of fibrous-rooted plants and for seedlings of all kinds. They peiiodically expose the mould to the air, and sift it so that no stones larger than the par- 310 CONCLUSION. Cbap. YH tides whicli they can swallow are left in it They mingle the whole intimately together, like a gardener who prepares fine soil for his choicest plants. In this state it is well fitted to retain moisture and to absorb all soluble Bubsiances, as well as for the process of nitri- fication. The bones of dead animals, the harder parts of insects, the shells of land- molluscs, leaves, twigs, (5^c., are before long all buried beneath the accumulated castings of worms, and are thus brouglit in a more or less decayed state within reach of the roots of plants. Worms likewise drag an infinite number of dead leaves and other parts of nlants into their burrows, partly for the sake of plugging them up and partly as food. The leaves which are dragged into the bur- rows as food, after being torn into the finest shreds, partially digested, and saturated with the intestinal and urinary secretions, are com- mingled with much earth. This earth forms the dark coloured, rich humus which almost everywhere covers the surface of the land with a fairly well-defined layer or mantle. "\^on Hen sen* placed two worms in a vessel ♦ ' Zeitschrift fiir wissenschaft. Zoolog.' B, xxviii. 1877, p. 3B0. Chap. VII CONCLUSION. 311 J 8 inches in diameter, which was filled with sand, on which fallen leaves were strewed ; and these were soon dragged into their bur- rows to a depth of 3 inches. After about G weeks an almost uniform layer of sand, a centimeter ('4 inch) in thickness, was con- verted into humus by having passed through the alimentary canals of these two worms. It is believed by some persons that worm- burrows, which often penetrate the ground almost perpendicularly to a depth of 5 or 6 feet, materially aid in its drainage ; notwith- stsinding that the viscid castings piled over the mouths of the burrows prevent or check the rain-water directly entering them. They allow the air to penetrate deeply into the ground. They also greatly facilitate the downward passage of roots of moderate size ; and these will be nourished by the humus with which the burrows are lined. Many seeds owe their germination to having been covered by castings ; and others buried to a considerable depth beneath accumulated castings lie dormant, until at some future time they are accidentally uncovered and germinate 21 312 CONCLUSION. Chap. VII. Worms are poorly provided with sense- organs, for they cannot be said to see, although they can just distinguish between light and darkness ; they are completely deaf, and have only a feeble power of smell ; the sense of touch alone is well developed. They can therefore learn little about the outside world, and it is surprising that they should exhibit some skill in lining their burrows with their castings and with leaves, and in the case of some species in piling up their castings into tower-like constructions. But it is far more surprising that they should ap- parently exhibit some degree of intelligence instead of a mere blind instinctive impulse, in their manner of plugging, up the mouths of their burrows. They act in nearly the same manner as would a man, who had to close a cylindrical tube with different kinds of leaves, petioles, triangles of paper, &c., for they commonly seize such objects by their pointed ends. But with thin objects a certain number are drawn in by their broader ends. They do not act in the same unvarying manner in all cases, as do most of the lower animals; for instance, they do not drag in leaves by their Chap. YII. CONCLUSION. 313 foot-stalks, unless the basal part of the blade is as narrow as the apex, or narrower than it. When we behold a wide, turf-covered expanse, we should remember that its smooth- ness, on which so much of its beauty depends, is mainly due to all the inequalities having been slowly levelled by worms. It is a mar- vellous reflection that the whole of the super- ficial mould over any such expanse has passed, and will again pass, every few years through the bodies of worms. The plough is one of the most ancient and most valuable of man's inventions ; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earth-worms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures. Some other animals, however, still more lowly organised, namely corals, have done far more conspicuous work in having constructed innumerable reefs and islands in the great oceans ; but these are almost confined to the tropical zones. INDEX. A-binger, Eoman villa at, 178 • castings from Roman villa, with rounded particles, 258 Acids of humus, action on rocks, 240 Africa, dust from, 235 Air, currents of, worms sensitive to, 28 Amount of earth brought to the surface by worms, 129 Ants, intelligence of, 93 Archiac, T)\ criticisms on my views, 4 Artemisia, leaves of, not eaten by worms, 33 Ash-tree, petioles of, 79 Beaulieu Abbey, burial of the old pavement, 193 castings from, with rounded particles, 255 Beaumont, ]6lie de, on vegetable mould, 2 ■ ' *^e rubbish underlying great cities, 178 the transport of dust, 237 ■ ■ the permanence of mould, 289 the permanence of ancient tumuli, 290 Beech-forests, stones not buried uuder by castings, 144 Bengal, worms of, 123 Bones, crushed, burial of, under castings, 146 Brading, Koman villa at, 199 , castings from, with rounded particles, 264 316 INDEX. Bridgman, Mr., on worms eating leaves of a Phlox, 33 Buckman, on grasses profiting by being rolled, 10 Burial of the remains of ancient buildings by worms, 176 Burrows, depth of, 109 direction of, on a slope, 270 excavation of, 98 lined with black earth, 111 lined with leaves, 112 mouths of, worms lie motionless near, 15 old, their collapse, 118 — plugged up, 58 terminating in a small chamber, often lined wit^h stones or seeds, 114 Calciferous glands, 17, 43 Cannibal worms, 36 Carnagie, Mr., depth of burrows, 114 Castings, acid, 52 from Beaulieu, 101 ■ tower-like, near Nice, 106 ejection of, 116 tower-like, from near Calcutta, 123 of great size on the Nilgiri Mountains, 126 weight of, from a single burrow and from a given area, 160 _ thickness of layer formed from, during a year, 169 ejected over ancient buildings, 253 flowing down slopes, 261 washed away, 272 ■ — dry, disintegration of, 275 blown to leeward, 283 Cells, free, with calcareous matter in the calciferous glands, 47 Cellulose, digestion of, 37 INDEX. 317 Chalk-formation, surface of, much denuded, 137 Clialk, residue of, forming a superficial deposit, 138 fragments of, soon buried and corroded, 139 formation of mould over, 297 Ched worth, Eoman villa of, 197 Circular trenches near Stonehenge, 287 Claparede, structure of the intestines of worms, 19 on the salivary glands of worms, 42 on the calciferous glands, 44 ■ the pharynx adapted for suction, 56 doubts whether earth serves worms as food,, 102, 105 on the gizzards of worms, 246 Clematis, petioles of, used in plugging up burrows, 58, 77 Cobra-snake, intelligence of, 94 Collapsing of old burrows, 118 Concluding remarks, 305 Concretions of lime in the anterior calciferous glands, 45* calcareous, use of, 54 Corals, mud derived from, 256 Corniche Eoad, disintegrated castings on, 276, 281 Croll, Mr., on denudation, 233 Crowns or ridges on old ploughed fields, 292 Currents of air, worms sensitive to, 28 Dancer, Mr., on the action and number of worms, 146, 159 Deafness of worms, 26 Debris, over the Eoman remains at Silchester, 201 Decay of leaves not hastened by the secretion with which they are bathed, 38 I^enudation of the land, 230 Depth to which worms burrow, 109 Ligaster, 246 318 INDEX. Digestion of worms, 37 exti a-stomachal, 43 Disintegration of rocks, aided by worms, 240 Distribution of worms, 120 Down, amount of earth here brought annually to Uie surface, 137 Downs near Winchester, valleys in, 301 Dust, distance transported, 235-237 Earth, amount of, brought to the surface by worms, 129 amount of, which flows down a given slope, 266 swallowed as food, 100 weight of, ejected from a single burrow, 160 Eisen, number of species of worms, 9 depth of burrows, 110 Ejection of castings, 116 Embankments on hill-sides, 278, 282 Encampmeuts, ancient, 290 Ernst, Dr., on worms at Caracas, 121 Excavation of the barrows, 98 Fabre, M., on the instincts of Sphex, 93 Farrer, Mr. T. H., on the Koman villa at Abinger, 178-188 Fat eaten by worms, 36 Fields formerly ploughed, 292 Fish, Mr., criticisms on my views, 6 Flints, standing vertically in the residue over the chalk, 138 acted on externally and internally by atmospheric agencies, 245 Flowing down of castings, 261 Fluid, digestive, of worms, 37 INDEX. 319 Food of worms, leaves, 35 earth, 100 Foster, Michael, on the pancreatic ferment, 37 on the acidity of the contents of the intestines, 52 Foundations, deep, of the Eoman buildings at Wroxeter, 227 Furrows on old ploughed fields, 292 Galton, Mr., on the number of dead worms, 14 Geikie, Archibald, on Denudation, 238 controverts E. de Beaumont's views on Denudation, 289 , James, controverts Richthofen's views, 237 on glaciated rocks, 245 Geographical distribution of worms, 120 Gizzards of worms, 246 Glands, calciferous, 17, 43 function of, 49 Glen Roy, evidence of rarity of debacles, 260 Haast, Von, on aboriginal instruments in New Zealand found buried, 147 Hearing, sense of, 26 Heat, perception of, 25 Heaths, inhabited by few worms, except where patha cross them, 10 Hensen on the number of worms in gardens, 5 on worms not subsisting on earth, 108 depth of burrows, 110 on number of worms living in a given area, 158 on the composition of mould, 238 — on the amount of humus formed by two worms, 310 320 INDEX. HensloWj Prof., on ledges on hill-sides, 278 Hoffineister, number of species of worms, 9 on worms liybernating in company, 34 perception of light by worms, 20, 22 on the enemies of worms, 62 — depth of burrows, 110 on hybernation of worms, 114 Hooker, Sir J., on ledges of earth on the Himalaya, 278 Humus acids, action of on rocks, 240, 244 Instinct of worms, 35 Intelligence of worms, 35, 64 Intestines of worms, their contents acid, 51 Islands, inhabited by worms, 120 Johnson, Dr. H., on the Eoman remains at "Wroxcter, 222-228 on ammonia in worm-castings, 242 Johnson, S. W., ' How Crops Feed,' 242 Joyce, Rev. J. G., on the Eoman remains at Silchester, 201 Jiilien, Mr. A. A., on the composition of peat, 238 on the humus acids, 240, 244 Key, Eev. H., on the burial of cinders by worms, 146 King, Dr., on the formation of mould in forests in France, 5 on castings near Kice, 106, 117 on great castings on the Nilgiri MouDtainfl and in Ceylon, 126 weight of castings near Nice, 163 on disintegrated castings on the Corniche road, 276, 281 on the washing away of the castings r^n the Nilgiri Mountains, 274 INDEX. S2I Knole Park, beech- woods, worms absent, 12 Koninck, De, on the disintegration of rocks, 235 Laburnum leaves, 67 Land, denudation of, 230 Lankester, Eay, on the structure of worms, 18 on worms from Kerguelen Land, 121 La Plata, dust storms of, 236 Layard, Mr., on the habits of the cobra, 94 Leaves, worms distinguish the taste of different kinds, 82 consumed by worms, 35 their decay not hastened by the alkaline secretion with which they are bathed, 38 decayed, generate acids, 50 used in plugging up burrows, 65 used to line burrows, 112 Ledges of earth on hill- sides, 278 Leon, R, on the digestive fluid of worms, 38 Light, perception of, by worms, 20 Lime, carbonate, concretions of, 45 Maer Hall, amount of earth brought to surface, 130 Mallett, Mr,, on the sinking of the ground under great buildings, 158 Meat, raw, eaten by worms, 36 Mental qualities of worms, 34 Mint, leaves of, only nibbled, 33 Mississippi, drainage area of, 233 Mobius on the habits of a pike, 94 Moniligaster, 246 Morren on worms surviving long immersion, 13 '■ — on worms lying motionless near mouths of their burrows, 15 822 INDEX. MorrcD on worms eating sugar, 36 on the disappearance of the calciferous glands during winter, 48 on stones in tlie gizzards of worms, 247, 249 Mould, thickness of, annually ejected by worms, 169 thickness of, over Koman remains at Ohedworlli, 199 nature and thickness of, over the Koman remains at Silchester, 218 ' thickness of, at Wroxeter, 223 formation and thickness of, over the chalk, 297 Mountains, worms absent from, 12 Miiller, Fritz, on the worms in' South Brazil, 121 Nice, castings near, 106 disintegrated castings near, 276 Night, worms leave their burrows, 14 Nilgiri Mountains, castings on, 126 Objects strewed on the surface soon buried under cast ings, 130 Obliteration of old furrows on ploughed land, 292 Odours, degree of sensitiveness to, by worms, 29 Pancreatic secretion, 37 ■ not acid, 53 Paper, triangles of, 82 Path, paved, burial of, by worm-castings, 146 Paths inhabited by worms, 10 Pavement, modern, undermined by worms, 192 Pavements, ancient, subsidence of, at Silchester, 212 Peat, formati'.m of, 239 Percolation of earth into the chalk, 297 INDEX. 323 Perichaeta, naturalized near Nice, 106 Perrier, worms surviving long immersion, 13 on tlie calciferous glands, 44 — — on tlie action of the pharynx, 56 on the burrowing power of worms, 99 on naturalized worms, 106 on worms killed by acetic acid, 159 on the gizzards of worms, 246, 249 Petioles of Clematis, 77 of the ash, 79 Pharynx, action of, 56 Pike, stupidity of, 94 pine-leaves used in plugging up burrows, 58, 70 lining burrows, 112 Pipes, formation of, in the chalk, 137 Playfair on Denudation, 290 Ploughed fields, old, 292 Plugging up of the burrows, 58 ■ use of the process, 62 Prehension, power of, by worms, 56 Qualities, mental, of worms, 34 Ramsay, Mr., on the sinking of a pavement undermined by worms, 192 on Denudation, 231 Remains, ancient, buried by worms, 176 Rhododendron leaves, 69 Eichthofen on dust deposits in China, 237 Eobinia, petioles of, 81 Hocks, disintegration of, aided by worms, 240 triturated in the gizzards of worms, 249 Eolling down of dry castings, 275 Romanes, Mr., on the intelligence of animals, 95 324 INDEX. Sachs on living roots corroding rocks, 243 Sage, leaves of, not eaten by worms, 33 Saliva, doubtful whether any secreted by worms, 42 Saussure, H. De, on brick-pebbles, 254 Schmulewitsch on the digestion of cellulose, 37 Scott, Mr. J., on worms near Calcutta, 123 Seeds preserved in the burrows of worms, 115 Semper on various animals swallowing sand, 102 Senses of worms, 19 Silchester, old Roman town, 201 Silica, colloid, acted on by the humus acids, 242 Sinking of the pavemente at Silchester, 212 Sites inhabited by worms, 9 Smell, sense of, 29 Social feelings of worms, 34 Sorby, Mr., on the trituration of small particles of rock, 257 Starch eaten by worms, 36 digestion of the granules in the cells of leaves, 41 St. Catherine's Hill, near Winchester, 302 Stones, great, undermined by worms at Leith Hill and at Stonehenge, 148 ■ small, heaped over burrows, 60 small, in the gizzards of worms, 247 rounded in tlie gizzards of worms, 249 Stonehenge, great stones of, undermined by worms, 154 circular trenches near, 287 Structure of worms, 16 Subsidence of the pavements at Silchester, 212 Suction, power of, 56 Sugar eaten by worms, 36 Summary of whole book, 305 Surface, objects strewed on, buried under castings, 130 INDEX. 325 Taste, power of, 32 Thickness of the layer of mould annually ejected by worms, 169 ' of the mould over the remains at Ched worth, 199 — ^ of the mould over the remains at Silchester, 218 — of the mould over the Roman remains at Wroxeter, 223 Thyme, leaves of, not eaten by worms, 38 Touch, worms highly sensitive to, 28 Triangles of paper, 82 Trituration of particles of reck in the gizzards of wormSj 249 Tumuli, ancient, 290 Tylor, Mr. A., on Denudation, 233 Tylor, Mr. E., on anciently ploughed land, 293 Typhosolis, 19 Utricularia, bladders of, 109 Vibrations, worms sensitive to, 27 Vision, power of, in worms, 20 Walls, ancient, at Abinger, penetrated by worms, 188 penetrated by worms at Silchester, 209 Washing away of castings, 272 Wedgwood, Mr., on the formation of mould, 3 Weight of earth ejected from a single burrow, 160 Whitaker, Mr., on Denudation, 232 White, on worms leaving their burrows at night, 14 Winchester, chalk formation near, 301 Wind, action of, on castings, 283 Worms, nocturnal, 13 large numbers occasionally die, 14 dead eaten by other worms, 36 326 INDEX. Worms, contents of intestines, acid, 51 their castings, acid, 52 power of suction, 56 plugging up their burrows, 58 — intelligence of, 64 — formation of their burrows, 98 number of, living in a given area, 158 penetrating ancient walls, 188, 209 gizzards of, and the trituration of the contained stones, 246 prefer to live in fine earth, 291 Wright, Mr., on the age of Wroxeter, 221 Wroxeter, old Eoman to^n of, 221 DATE DUE 1 8 ■oM] 1 i UNIVERSITY PRODUCTS, INC. #859-5503 BOSTON COLLEGE 3 9031 01766370 9 44/J7 BOSTON COLLEGE LIBRARY UNIVERSITY HEIGHTS CHESTNUT HILL. MASS. Books may be kept for two weeks and may be renewed for the same period, unless reserved. Two cents a day is charged for each book kept overtime. If you cannot find what you want, ask the Librarian who will be glad to help you. The borrower is responsible for books drawn on his card and for all fines accruing on the same. \ M "*-»«