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. I. FOOD AND DIGESTION. flowers. But they will also consume fresh leaves, as I 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

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. free calciferous cells. As the smaller concretions increase in size, they come into contact and unite, thus enclosing the now functionless lamellæ; and by such steps the formation of the largest concretions could be followed. Why the process regularly takes place in the two anterior glands, and only rarely in the four posterior glands, is quite unknown. Morren says that these glands disappear during the winter; and I have seen some instances of this fact, and others

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

, 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 influence in determining the manner in which lime leaves are dragged into the burrows. The considerable proportion, 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

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. 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 burrows more easily by the base or foot-stalk

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. gnawed the bases, though this is in itself probable. Out of 1 2 1 petioles extracted from burrows early in February, 68 were imbedded by the base, and 53 by the apex. On February 5 all the petioles which had been drawn into the burrows beneath a Robinia, were pulled up; and after an interval of eleven days, 35 petioles had been again dragged in, 19 by the base, and 16 by the apex. Taking these two lots together, 56 per cent, were drawn in by the base, and 44 per cent

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

matter of chance. In eight cases, two triangles had been drawn into the same burrow, and in seven of these cases, one had been drawn in by the apex and the other by the base. This again indicates that the result is not determined by chance. Worms appear sometimes to revolve in the act of drawing in the triangles, for five out of the whole lot had been wound into an irregular spire round the inside of the burrow. Worms kept in a warm room drew 63 triangles into their burrows; but, as in the case 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. 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 by extremely complicated movements and by the shortest

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. EJECTION OF THEIR CASTINGS. When a worm comes to the surface to eject earth, the tail protrudes, but when it collects leaves its head must protrude. Worms there-fore must have the power of turning round n their closely-fitting burrows; and this, as it appears to us, would be a difficult feat. As soon as a little heap has been 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

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 WIDE DISTRIBUTION. 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 observations 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

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. III. BROUGHT UP BY WORMS. cinders had been strewed, only about half-a-year before, and these either still lay on the surface or were entangled among the roots of the grasses; and I here saw the commencement of the burying process, for worm-castings had been heaped on several of the smaller fragments. After an interval of 4 3/4 years this field was re-examined, and now the two layers of lime and cinders were found almost everywhere at a greater depth than before by nearly 1 inch, we will

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

has been heaped on the surface at an average annual rate of from .2 to .22 of an inch. But in this district when a ploughed field is first laid down in grass, the mould accumulates at a much slower rate. The rate, also, must become very much slower after a bed of mould, several inches in thickness, has been formed; for the worms then live chiefly near the surface, and burrow down to a greater depth so as to bring up fresh earth from below, only during the winter when the weather is very cold

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. III. BROUGHT UP BY WORMS. of dark-coloured vegetable mould, and the next 18 inches of sandy loam, containing in the lower part many rolled pieces of sand-stone, with some bits of brick and tile, probably of Roman origin, as remains of this period have been found close by. The sandy loam rested on an indurated ferruginous pan of yellow clay, on the surface of which two perfect celts were found. If, as seems probable, the celts were originally left on the surface of the land, they have

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. III. UNDERMINED BY WORMS. 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 conclusion, the raised surrounding border of turf was only 1 inch high in some parts, and 2 inches in other parts. There were

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. III. BROUGHT UP BY WORMS. 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 mountains one casting 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

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. III. BROUGHT UP BY WORMS. 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

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. IV. OF ANCIENT BUILDINGS. ing fields; but on this 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 when a fresh burrow is spoken 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 when no earth was ejected from them. I have often observed the same fact

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

, 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. From 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

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. 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 concrete on which tiles had once rested. The fine mould beneath the turf on

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

ashes fell over the remains of any building, their disintegration in the course of time, and the sifting action of worms, 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 Koman and other old buildings in England; but no doubt the washing down of soil from the neighbouring higher lands, and the deposition of dust, have together aided largely in the work 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

CHAP. V. AND DENUDATION. 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

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. lying the chalk (the residue of its dissolution by rain-water) 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

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

DISINTEGEATION CHAP. V. 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 concretions formed in the calciferous glands, which are often found in their gizzards, intestines, and occasionally in their castings, when of large size, sometimes appeared

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

DISINTEGRATION CHAP. V. overlying the buried tesselated pavement, through which worm-burrows passed; and these castings contained innumerable particles of tiles and bricks, of concrete and cement, the majority of which had manifestly undergone 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

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. VI. AIDED BY WORMS. water-spouts would remove all the mould from a very gentle slope; but when examining 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 was 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 inclined surface, covered with vegetation and matted

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. VI. AIDED BY WORMS. 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 collapsed from the weight of the superincumbent