The result was different when cabbage-leaves and pieces of onion were employed, both of which are devoured with much relish by worms.Small square pieces of fresh and half-decayed cabbage- leaves and of onion bulbs were on nine occasions buried in my pots, beneath about 0.25 of an inch of common garden soil; and they were always discovered by the worms.One bit of cabbage was discovered and removed in the course of two hours; three were removed by the next morning, that is, after a single night; two others after two nights; and the seventh bit after three nights.Two pieces of onion were discovered and removed after three nights.Bits of fresh raw meat, of which worms are very fond, were buried, and were not discovered within forty-eight hours, during which time they had not become putrid.The earth above the various buried objects was generally pressed down only slightly, so as not to prevent the emission of any odour.On two occasions, however, the surface was well watered, and was thus rendered somewhat compact.After the bits of cabbage and onion had been removed, I looked beneath them to see whether the worms had accidentally come up from below, but there was no sign of a burrow; and twice the buried objects were laid on pieces of tin-foil which were not in the least displaced.It is of course possible that the worms whilst moving about on the surface of the ground, with their tails affixed within their burrows, may have poked their heads into the places where the above objects were buried; but I have never seen worms acting in this manner.Some pieces of cabbage-leaf and of onion were twice buried beneath very fine ferruginous sand, which was slightly pressed down and well watered, so as to be rendered very compact, and these pieces were never discovered.On a third occasion the same kind of sand was neither pressed down norwatered, and the pieces of cabbage were discovered and removed after the second night.These several facts indicate that worms possess some power of smell; and that they discover by this means odoriferous and much- coveted kinds of food.
It may be presumed that all animals which feed on various substances possess the sense of taste, and this is certainly the case with worms.Cabbage-leaves are much liked by worms; and it appears that they can distinguish between different varieties; but this may perhaps be owing to differences in their texture.On eleven occasions pieces of the fresh leaves of a common green variety and of the red variety used for pickling were given them, and they preferred the green, the red being either wholly neglected or much less gnawed.On two other occasions, however, they seemed to prefer the red.Half-decayed leaves of the red variety and fresh leaves of the green were attacked about equally.When leaves of the cabbage, horse-radish (a favourite food) and of the onion were given together, the latter were always, and manifestly preferred.Leaves of the cabbage, lime-tree, Ampelopsis, parsnip (Pastinaca), and celery (Apium) were likewise given together; and those of the celery were first eaten.But when leaves of cabbage, turnip, beet, celery, wild cherry and carrots were given together, the two latter kinds, especially those of the carrot, were preferred to all the others, including those of celery.It was also manifest after many trials that wild cherry leaves were greatly preferred to those of the lime-tree and hazel (Corylus).According to Mr.Bridgman the half- decayed leaves of Phlox verna are particularly liked by worms.
Pieces of the leaves of cabbage, turnip, horse-radish and onion were left on the pots during 22 days, and were all attacked and had to be renewed; but during the whole of this time leaves of an Artemisia and of the culinary sage, thyme and mint, mingled with the above leaves, were quite neglected excepting those of the mint, which were occasionally and very slightly nibbled.These latter four kinds of leaves do not differ in texture in a manner which could make them disagreeable to worms; they all have a strong taste, but so have the four first mentioned kinds of leaves; and the wide difference in the result must be attributed to a preference by the worms for one taste over another.