12 J. T. Gulick — Inconsistencies of Utilitarianism. 



Incompatibilities will disappear unless preserved by Positive 



Segregation. 



Mr. Wallace lias given a very instructive computation on 

 pages 181-4 ; but it does not seem to me to prove, as he supposes, 

 that infertility between the individuals of a species cannot 

 increase "unless correlated with some useful variation," but 

 that it cannot arise, except as a transitory variation, unless 

 associated with some positively segregative principle, causing 

 those to pair together which are fertile with each other. My 

 contention is that, without some positive form of segregation 

 fecundity and cross sterility can never arise ; and that after it 

 has arisen under segregation, no amount of correlation with 

 useful variation will preserve it, if the positive segregation is 

 removed. If, for example, all the species of humming birds 

 were brought together in one country, and were deprived of 

 all segregative habits and instincts, it certainly would not 

 require many generations to reduce them to one species. If 

 equally adapted to the environment, the species that would 

 succeed in perpetuating itself would be the one represented 

 by the largest number of individuals ; or if several species 

 were entirely cross fertile and were in the aggregate represented 

 by a larger number of individuals than any other similar group 

 of species or than any single species, then, the resulting species 

 would be the hybrid descendants of this most numerous group. 

 All the other species would become extinct through failing to 

 mate with " physiological complements." 



Why any need of distinctive Recognition Marks for those whose 

 Ancestors had but one set of Marks. 



An example of one of the effects of divergence being 

 treated as if it were the primary cause of divergence is found 

 on pages 217-228 and 284, where the need of distinctive 

 characters for easy recognition is given as the chief cause of 

 divergence in calls, odors, and colors. The importance of 

 distinctive characters by which the members of a species may 

 distinguish their mates from those of other species cannot be 

 exaggerated ; but how does it happen that the descendants of 

 one stock which had originally but one set of such characters, 

 have become segregated into groups, needing distinctive marks. 

 By confounding the j)roblem of successive, monotypic adapta- 

 tion with that of coexistent, polytypic adaptation the real 

 causes of divergence have been obscured and misapprehended. 

 The diversity of Sexual and Social Selection, which Mr. 

 "Wallace in these passages speaks of as natural selection, is due 

 to diversity of sexual and social instincts which in their turn 

 have been produced by different forms of segregation. For a 



