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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
of the land where worms abound soon get 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-examined after the interval of a few years, such objects were found
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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, 83 87 pounds per square yard; or 18 12 tons per acre, assuming the whole 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 accuracy I can implicitly rely
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
. 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
mould together with the turf was only 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 days collection was on October 14th, 1871. The castings were then well dried before a fire; and they weighed exactly 3 lbs. This would give for an acre of similar land 7 56 tons of dry earth annually ejected by worms. The second
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 consider how much matter is daily brought into a great city for building, fuel, clothing and food
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
open burrows on the broken summit of the eastern wall (W in Fig. 8); and, on September 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. We 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 VIII., and there now
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 astonishing number of half-decayed leaves which they draw into their burrows to a depth of 2 or 3 inches. They do this chiefly for obtaining 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
carbonate of lime and on the oxides of iron. It is, also, known that some of these acids, which were called long ago by Th nard azohumic, 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
in the ground. The living roots of plants, moreover, as Sachs 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 here 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
therefore necessary to obtain flints for building purposes from the bed of red clay overlying 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 up and swallowed by the worms, for they were found in their castings, intestines, and gizzards. They even swallowed the coarse red dust, formed by the pounding of the tiles. Nor can it be supposed that they mistook the beads and fragments for food; for we have seen that their taste is delicate enough to distinguish between different kinds of leaves. It is
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 concretions formed in the calciferous glands, which are often found in their gizzards, intestines, and occasionally
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
There were also very many particles of hard mortar, about half of which were well 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
will never be removed as long as the 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 castings, by our wet southern gales to the northeast, over open and flat land, by looking to the level of the surface on opposite sides of old trees and hedge-rows; but I failed owing to the unequal growth of the roots of trees and to most pasture-land having been formerly ploughed. On an
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 furrows, it would be more favourable for
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
and the particles composing it are thus rubbed together. By these means fresh surfaces 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
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F1357    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray.   Text   Image   PDF
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 geologist considers extremely
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
I 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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 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 doctrines of lie de Beaumont, wrote about my singuli re th
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 power of smell Taste Mental
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 sward. Whether this change
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
which runs in a straight course to the vent at the posterior end of the body. The intestine presents a remarkable structure, the typhosolis, or, as the old anatomists called it, an intestine within an intestine; and Clapar de* 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
fashion. This is shown by the manner in which the species of Perich ta 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 plugging up the mouths of their burrows with various objects; and very young worms act in this manner. But some degree of intelligence appears, as we shall see in the
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 they were affected in a peculiar manner by the secretion poured out of their mouths. The upper surfaces of the leaves, over which the worms had crawled, as was shown by the dirt left on them, were marked in sinuous lines, by either a
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 improbable that the worms
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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-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 difficult
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 exceptional cases. In order, therefore, that worms should do their work well
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 towards the mouths of their burrows; and one worm tried in a
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 taste had been lost; and
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
possible to ascertain whether worms had gnawed the bases, though this is in itself probable. Out of 121 petioles extracted from burrows early in February, 68 were embedded 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 the pine-leaves, they
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. 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 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; but then they were working
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
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 burrows may be abridged as
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
25 16 of the narrow ones 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
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F1361    Book:     Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. fifth thousand (corrected), and with textual changes. London: John Murray.   Text   Image   PDF
petioles of foreign plants, wholly unknown to the progenitors of the worms which act in the described manner. Nor are their actions so unvarying or inevitable as are most true instincts. As worms are not guided by special instincts in each particular case, though possessing 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
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