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. ANCIENTLY PLOUGHED FIELDS. on the 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

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

amount of sediment annually delivered into the sea by the Mississippi, that its enormous drainage-area must on an average 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

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

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 country has passed many times through, and will again pass 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 doctrines of lie de Beaumont, wrote about my singuli re th orie

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

In the year 1869, Mr. Fish * rejected my conclusions with respect to the part which worms have played in the formation of vegetable 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 we 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

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

Eisen;* but two of these rarely burrow in the ground, and one inhabits very wet places or even lives under the water. We are here concerned only with the kinds which bring up earth to the surface in the form of castings. Hoffmeister 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

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

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 thickness of a few 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

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

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 G 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

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

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 raw and roasted meat were

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

proportion of the laburnum leaves not having been drawn in by the base, by worms having acquired the habit of generally drawing in leaves by their tips and thus avoiding the foot-stalk. For the basal margin of the blade in many kinds of leaves forms a large angle with the foot-stalks; 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 difficult

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

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 towards the mouths of their burrows; and one worm tried in a senseless manner to drag them into the burrow by

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

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 exposed to the weather for eight

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

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 seleced 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; but then they were working

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

alone 65 14 21 If we consider these several cases, we can hardly 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

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

. 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 mass 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 of the reddish sand and partly of black earth brought up from

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 them, mingled with fragments of other kinds of leaves, drawn in to a depth of 4 or 5 inches. Worms often remain, as formerly stated, for a long time close to the mouths of their burrows, apparently for warmth; and the basket-like structures formed of leaves would 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

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

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 castings a fact which much

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

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 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 surface in most or all parts of the

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

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 (at which time worms were found in this

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

thirty-five years, as far as I could judge, about 1 inch; and this must have been due to the brick-rubbish beneath the more Protuberant 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

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

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

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

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, and generally the mouths 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

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 occurred a greater amount of mould

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

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 the sides of the several holes

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

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 Roman 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 concealment. Dust would be apt to

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

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