1908] The Polymorphism of Ants 63 



the action of natural selection on fortuitous constellations of 

 determinants in the germ-plasm of the queen. If we grant 

 the possibility of a periodical influx of worker germ-plasm 

 into that of the species, the transmission of characters acquired 

 by this caste is no more impossible than it is in other animals, and 

 the social insects should no longer be cited as furnishing conclu- 

 sive proof of Weismannism. 



Plate has attempted to overcome the difficulties pre- 

 sented by the normal sterility of the worker by supposing that 

 the distinguishing characters of this caste arose prior to its 

 inability to reproduce. He recognizes the following stages in 

 the phylogeny of the social insects. 



" I . The presocial stage with but a single kind of male and 

 female. 



"2. The social stage with but a single kind of male and 

 female. The peculiarities in nesting, caring for the brood, and 

 other instincts were already developed during this stage. 



" 3 . The social stage with one kind of male and two or several 

 kinds of females, which were all fertile, but in consequence of the 

 physiological division of labor became more and more different 

 in the course of generations. The division of labor took place in 

 such a manner that the sexual functions passed over primarily to 

 a group A, while the construction of the nest, predatory expedi- 

 tions and other duties devolved mainly on another group of indi- 

 viduals (B) which on that account used their reproductive organs 

 less and less. 



"4. The present stage with one kind of male, a fertile form 

 of female, which arose from group A, and one or several kinds of 

 sterile females, or workers (group B)." 



Plate assumes that the differentiation into sterile and fer- 

 tile forms did not take place till stage 3 , and if I understand him 

 correctly, not till after "the races had become dift'erentiated 

 morphologically." This view, as he admits, resembles Spencer's. 

 The two views, in fact differ merely in degree, for the underlying 

 contention is the same, namely that sterility is one of the most 

 recently developed characters among the social insects. There 

 can be little doubt, however, that the smaller adaptive characters, 

 for example those of the females of certain Formicas above men- 

 tioned, must have made their appearance in the fourth stage of 

 Plate's scheme. The view which I have advocated differs from 

 Plate's in admitting that even in this stage the workers are fertile 



