54 Riley Presidential Address. 



control of the colony as a whole, by virtue of the treatment of 

 the larva, it will always be difficult to prove, though there is 

 every reason to believe that, as in the bees, there is, to some ex 

 tent, such control, and that the relative proportions of the differ 

 ent forms will depend upon circumstances. But the fact re 

 mains that, in ants, as in bees and wasps, the neuters are but 

 arrested females, and are capable of becoming, under exceptional 

 circumstances, fertile, and that we see in the different species all 

 gradations, not only as to the number of forms of the workers, 

 but as to the number of fertile females that are allowed in the 

 same colony to provide for the continuance of the species. We 

 also find in the same species great variation and gradation in the 

 characters of the different sets which form the community, es 

 pecially between the different forms of workers, in contrast to 

 what I have remarked as to bees and wasps. This has been re 

 corded not only by writers like Darwin and Lubbock, but by all 

 who have given close attention to the subject; while Ch. Lespes 

 (Ann. des Sciences Nat. (4) 20, pp. 241-251) in his " Observations 

 sur les Fourmis Neutres" has shown that all neuters have traces 

 of the female reproductive organs; that these traces vary in the 

 different species; and that where there are two forms of neuters 

 these pass insensibly into each other through intermediate forms. 

 The ants thus furnish us with varying degrees of social organiza 

 tion when the different species are considered, while the different 

 classes in the same species are not as definitely fixed as in the 

 bees or the wasps. 



Now it were comparatively easy to account for these neuters 

 among the social Hymenoptera and the different forms and attri 

 butes which they present, by putting aside natural selection, as 

 expounded by Darwin, and substituting therefor social selection 

 acting not on generations in time, but on the individual at once 

 by the manner of its bringing up ; and surely there would seem 

 to be sufficient justification for this course when we find not only 

 such great physiological and functional, but such profound 

 structural modifications induced by larval environment and nur 

 ture, as I have pointed out, especially between the queen and the 

 worker bee.* This has, in fact, been the chief explanation which 



*Mr. Herbert Spencer, in one of his rejoiners to Prof. Weismann, (Con 

 temporary Review, December, 1893) refers to a chapter on The Determination 

 of Sex by Prof, Geddes and Mr. Thompson in their " Evolution of Sex," 



