A2536    Review:     Bennett, J. Risdon. 1882. [Review of Earthworms]. Jenner and his successors. Leisure Hour Monthly Library, 31: 22.   Text

was in fact regularly ploughed, and still continues to be ploughed, by earthworms. He has shown us that the smoothness which we admire in a wide, turf-covered expanse is mainly due to all the inequalities having been slowly levelled by worms, and that the whole of the superficial mould over any such expanse has passed, and will pass again, every few years, through the bodies of worms! It was left for Pasteur to show that these innumerable and indefatigable ploughmen, whilst rendering to man such

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

HABITS OF WORMS. CHAP. I. 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 peat, 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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

worms often lie for hours almost motionless close beneath the mouths of their burrows. I have occasionally noticed the same fact with worms kept in * 'De Lumbrici terrestris Hist. Nat.' c., p. 14. [page]1

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

CHAP. II. PROTECTION OF THEIR BURROWS. according to Hoffmeister,* are the bitterest enemies of worms, or from the larger species of Carabus and Staphylinus which attack them ferociously, for these animals are nocturnal, and the burrows are opened at night. May not worms when the mouth of the burrow is protected be able to remain with safety with their heads close to it, 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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

CHAP. II. THEIR INTELLIGENCE. by worms into their burrows, though not to a great depth; of these 66 per cent, had been drawn in by the base or foot-stalk; and 34 per cent, by the tip. In this case, therefore, 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-walks in my garden a very large number of

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

HABITS OF WORMS. CHAP. II. It might perhaps be inferred from the facts as yet given, that worms somehow gain a general notion of the shape or structure of pine-leaves, and perceive that it is necessary for them to seize the base where the two needles are conjoined. But the following cases make this more than doubtful. The tips of a large number of needles of P. austriaca were cemented together with shell-lac dissolved in alcohol, and were kept for some days, until, as I believe, all odour or

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

HABITS OF WORMS. CHAP. II. petioles were pulled out of worm burrows early in January, and of these 51.5 per cent, had been drawn in by the base, and 48.5 per cent, by the apex. This anomaly was however readily explained as soon as the thick basal part was examined; for in 78 out of 103 petioles, this part had been gnawed by worms, just above the horse-shoe shaped articulation. In most cases there could be no mistake about the gnawing; for ungnawed petioles which were examined after being

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

HABITS OF WORMS. CHAP. II. 33 per cent, by the base. In five cases, two triangles were drawn into the same burrow. It may be suggested with much apparent probability that so large a proportion of the triangles were drawn in by the apex, not from the worms having selected this end as the most convenient for the purpose, but from having first tried in other ways and failed. This notion was countenanced by the manner in which worms in confinement were seen to drag about and drop the triangles

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

HABITS OF WORMS. CHAP. II burrow, that the broader end was not well adapted for this purpose —even in this case a large proportion would probably have had their basal ends dirtied. We may therefore infer—improbable as is the inference —that worms are able by some means to judge which is the best end by which to draw triangles of paper into their burrows. The percentage results of the foregoing observations on the manner in which worms draw various kinds of objects into the mouths of their

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

CHAP. II. EARTH SWALLOWED AS FOOD. 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 the weather is very dry or intensely cold. On my lawn the black vegetable mould or humus 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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

; and these, as it appears, are spread out on all sides by the worm as it travels up or clown its burrow. The lining thus formed becomes very compact 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 well 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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

soil, they contained extremely few bits of rock, the largest of which was only .15 inch in diameter. Dr. King saw in Ceylon a worm about 2 feet in length and 1/2 inch in diameter; and he was told that it was a very common species during the wet season. These worms must throw up castings at least as large as those on the Nilgiri Mountains; but Dr. King saw none during his short visit to Ceylon. Sufficient facts have now been given, showing that worms do much work in bringing up fine earth to the

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

the whole intervening 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 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 whole surface to be equally productive in castings. In the

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

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, five days after the ruins had been exposed, he observed four [page] 19

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

BURIAL OF THE REMAINS CHAP. IV. As the foundations of the walls generally lie 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 foundations; 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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

CHAP. V. AND DENUDATION. 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 inhabit, 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

F1362    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. 6th thousand (corrected). London: John Murray.   Text   Image   PDF

CHAP. VII. CONCLUSION. tides which 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 substances, as well as for the process of nitrification. The bones of dead animals, the harder parts of insects, the shells of land molluscs, leaves, twigs, c, are before long all buried beneath the accumulated castings of worms, and are thus

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

Park, where the ground beneath was bare of all vegetation, not a single casting could be found over wide spaces, even during the autumn. Nevertheless, castings were abundant on some grass-covered glades and indentations 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 subjacent rocks, into which worms cannot burrow during the winter so as to escape

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

plainly marked with their tracks. I have noticed 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

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

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

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

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 timid creatures would almost certainly exhibit some signs of any new impression, we may conclude that they did not perceive these

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

worms act in this manner. But some degree of intelligence 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 omnivoruous. They swallow an enormous quantity of earth, out of which they extract any digestible matter which it may contain; but to this subject I must recur. They also consume a large number of half-decayed leaves of all kinds, excepting a few which have an

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

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 secretion of this kind is found in the intestines of worms. As the leaves which are dragged into the burrows are aften dry and shrivelled, it is indispensable 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

F1364    Book:     Darwin, C. R. 1882. The formation of vegetable mould, through the action of worms, with observations on their habits. Seventh thousand. Corrected by Francis Darwin. London: John Murray.   Text   Image   PDF

neutralises the intestinal acids. When worms were kept in pots filled 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 in 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