Page:The Formation of Vegetable Mould through the Action of Worms (1881).djvu/261

 manner as gallinaceous and struthious birds swallow stones to aid in the trituration of their food, so it appears to be with terricolous worms. The gizzards of thirty-eight of our common worms were opened, and in twenty-five of them small stones or grains of sand, sometimes together with the hard calcareous concretions formed within the anterior calciferous glands, were found, and in two others concretions alone. In the gizzards of the remaining worms there were no stones; but some of these were not real exceptions, as the gizzards were opened late in the autumn, when the worms had ceased to feed and their gizzards were quite empty.

When worms make their burrows through earth abounding with little stones, no doubt many will be unavoidably swallowed; but it must not be supposed that this fact accounts for the frequency with which stones and sand are found in their gizzards. For beads of glass and fragments of brick and of hard tiles were scattered over the surface