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Almost everything is eaten by worms. They swallow enormous quantities of earth, from which they extract any digestible matter it may contain. Large numbers of half-decayed leaves of all kinds, excepting a few that are too tough and unpleasant to the taste, and likewise petioles, peduncles, and decayed flowers. Fresh leaves are consumed as well. Particles of sugar, licorice and starch, and bits of raw and roasted meat, and preferably raw fat, are eaten when they come into their possession, but the last article with a better relish than any other substance given to them. They are cannibals to a certain extent, and have been known to eat the dead bodies of their own companions.

The digestive fluid of worms, according to León Frédéricq, is analogous in nature to the pancreatic secretion of the higher animals, and this conclusion agrees perfectly with the kinds of food which they consume. Pancreatic juice emulsifies fat, dissolves fibrin, and worms greedily devour fat and eat raw meat. It converts starch into grape-sugar with wonderful rapidity, and the digestive fluid of worms acts upon the starch of leaves. But worms live chiefly on half-decayed leaves, and these would be useless to them unless they could digest the cellulose forming the cell-walls, for all other nutritious substances, as is well known, are almost completely withdrawn from leaves shortly before they fall off. It has been ascertained that cellulose, though very little or not at all attacked by the gastric juice of the higher animals, is acted on by that from the pancreas, and so worms eat the leaves as much for the cellulose as for the starch they contain. The half-decayed or fresh leaves which are intended for food 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, which has been assumed to hasten their decay, but which, from its alkaline nature, and from its acting both on the starch-granules and on the protoplasmic contents of the cells, is not of the nature of saliva, but a pancreatic secretion, and of the same kind as is found in the intestines of worms. As the leaves which are dragged into the burrows are often dry and shrivelled, it is indispensable for the unarmed mouths of worms that they should first be moistened and softened, their disintegration being thereby the more readily effected. Fresh leaves, however soft and tender they may be, are similarly treated, probably from habit. Thus the leaves are partially digested before they are taken into the alimentary canal, an instance of extra-stomachal digestion, whose nearest analogy is to be found in such plants as Dionæa and Drosera, for in them animal matter is digested and converted into peptone, not within a stomach, but on the surfaces of the leaves.