much as is the full-grown worker. Bee-larvae all receive similar food for three days only, and thus long they are undifferentiated, and may become either workers or queens; but they are then fed differently, and the decision is then given as to which ids in the ontogeny shall become dominant. It would be just the same if even older worker·larvae could be converted into queens by the supply of the royal food; for the ids with the primary constituents of the queen do not disappear, but are passed from cell to cell with the other ids through the whole ontogeny; and so long as they are so constituted as to become active on receiving a certain kind and quantity of food, they might be capable of development even later, so long as the parts of the fully developed insect have not begun to develop. In the case of bees it is not so: at least bee-cultivators assert that very young larvae of from one to four days old must be selected from among the workers in order to breed up an artificial queen. But according to Grassi, the larvae of termites may also, at the will of the workers that feed them, be converted into fertile females by being supplied with more abundant nourishment, consisting of a nutritive secretion from the salivary glands of their attendants (cf. Note XV, p. 67).
It is certainly very remarkable that this adaptation of the larval organism to the determining stimulus of a specific mode of nourishment should be so perfectly similar in two such different groups of insects as the bees and termites: for there can of course be no doubt that it has arisen independently in each group. But
