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Show 38 HABITS OF WORMS. CHAP. I. tious substances are almost completely withdrawn from leaves, shortly before they fall off. It bas, however, now been ascertained that cellulose, though very little or not at all attacked by the gastric secretion of the higher animals, is acted on by that from the pancreas.* The half-decayed or fresh leaves which worms intend to devour, are dragged into the mouths of their burrows to a depth of from one to three inches, and are then moistened with a secreted fluid. It has been assumed that this fluid serves to hasten their decay; but a large number of leaves were twice pulled out of the burrows of worms and kept for many weeks in a very moist atmosphere under a 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 confinernent and examined early on the next morning, therefore not many hours after they bad been dragged into the burrows, the fluid * Schmulewitsch, 'Action des Sues digestifs sur la Cellulose.' Bull. de l'Acad. Imp. de St. Petersbourg, tom. xxv. p. 549. 1879. CIIAP. I. FOOD AND DIGESTION. 39 with which they were moistened, when tested with neutral litmus paper, showed an alkaline reaction. '"fhis was repeatedly found to be the case with celery, cabbage and turnip leaves. Parts of the same leaves which had not Leon rnoi~tened by the worms, were pounded with a few drops of distilled water, and the juice thus extracted was not alkaline. Some leaves, however, which had been drawn into burrows out of doors, at an unknown antecedent period, were tried, and though still moist, they rarely exhibited even a trace of alkaline reaction. The fluid, with which the leaves are bathed acts on them whilst they are fresh or nearly' fresh, in a remarkable manner; for it quickly kills and discolours them. Thus the ends of a fresh carrot-leaf, which had been dragged into a burrow, wore found after twelve hours of a dark brown tint. Leaves of celery, turnip,. rnaple, elm, lime, thin leaves of ivy, . and occasionally those of the cabbage were similarly acted on. The end of a leaf of Triticum repen.s, still attached to a growing plant, had been drawn into a burrow, and this part was dark brown and dead, whilst the |
