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Show 248 DISINTEGRATION CHAP. 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 up and swallow~d by ~he w~rms, for they were found in theu castings, Intestines, and gizzards. They even swallo~ed the coarse red dust, formed by the pounding of the tiles. Nor can it be supposed that they mistook the beads and fra?'ments f~r food; for we have seen that thmr taste 1s delicate enough to distinguish between different 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 h~rd objects are not necessary for crushmg 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.' tom. iii. 18i4, P· 419. CrrAP. V. AND DENUlJA'riON. 249 therefore cannot have the power of utilising stones. During the grinding process, the particles of earth must be rubbed 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 conclusion is supported by the appearance of freshly ejected castings, for these often reminded me of the appearance of paint which has just been ground by a workman between two fiat stones. Morren remarks that the intestinal canal is "impleta tenuissima terra, veluti in pulverem redacta." * Perrier also speaks of '' l'etat de pate excessivement fine a laquelle est reduite la terre qu'ils rejettent," &c.t .A.s 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. 16. t 'Archives de Zoolog. Exper.' tom. iii. 1874, p. 41R. |