given it as his opinion that the degeneration of the ovaries of the workers is simply due to an increased sensitiveness of the 'germ-plasm' to poor nourishment; and has explained the whole phenomenon of the formation of neuters among insects as consequent on such an altered mode of reaction in the germ-plasm. If it is thereby meant that the ovary is more easily affected by slight nutrition than are the ovaries of other insects, the supposition is hardly correct. It fails to explain the facts; for the ovary of the workers is not only in an undeveloped condition, but is actually rudimentary: the majority of the typical parts are wanting. Even if it be assumed that the number of ovarian egg-tubes has increased in the queen since the caste of workers arose, there can nevertheless be no doubt that at the same time it has diminished greatly in the case of the workers. This follows from the discoveries of Adlerz as regards ants, from which it appears that the degree of diminution in the number of egg-tubes is different in different species; the number varies from twelve to one, and in the case of Tetramorium caespitum they are even totally absent. But the rudimentary condition of the reproductive organs becomes even more apparent when we consider that both the bursa copulatrix and the receptaculum seminis have degenerated in the bee and ant workers; and we have every reason for believing that typical parts could never disappear owing to poor nourishment, no matter how poor it may have been—an egg-tube would no more disappear from this cause than would a leg or a wing. How often have caterpillars been reared
