Page:The Effect of External Influences upon Development.djvu/47

opinion that the origin of such dwarf workers must depend on a special peculiarity of the germ-plasm; for the defectively fed larvae were not starved to death, but underwent metamorphosis, merely remaining small. This special peculiarity of the germ-plasm, however, does not consist in an increased sensibility, and can only be the result of a complete metamorphosis of the whole germ-plasm, which in the case of the worker-ids has in fact become altered just as was necessary for the production of a body of small dimensions. For we cannot seriously suppose that these larvae are really insufficiently nourished and kept small by hunger (see Note XIII, p. 65). They get exactly as much nourishment as they need for the development of the worker-type, and as their instinct demands from the time when they have become worker-larvae owing to the poorer food (see Note XIV, p. 66). The primary constituents concerned with instinct in the worker-ids are modified, just as are those of the queen-ids. Concurrently with the visible alterations in bodily form, invisible variations have also occurred, as we may conclude from the fact that there has been variation in the instincts. But we know that the 'art' of rearing from the larva either a worker or a queen by means of a definite mode of feeding is an instinct which can only have been formed along with the development of the worker-type; moreover, the instinct of more moderate food-requirements will likewise have developed at the same time in the larva of the worker. For the worker-larva is a distinct individual with its own peculiar tendencies (Anlagen) and instincts, just as