J. T. Gulick — Inconsistencies of Utilitarianism. IT 



introduced by Mr. "Wallace, the commencement of infertility 

 between the incipient species is in relations to each other of 

 two portions of a species that are locally segregated from the 

 rest of the species, and partially segregated from each other 

 by different modes of life. These two local varieties, by the 

 terms of his supposition, being better adapted to the environ- 

 ment than the freely interbreeding forms in other parts of the 

 general area, increase till they supplant these original forms. 

 Then, in some limited portion of the general area, there arise 

 two still more divergent forms, with greater mutual infertility 

 and with increased adaptation to the environment, enabling 

 them to prevail throughout the whole area. The process here 

 described, if it takes place, is not modification by natural 

 selection. The natural selection of which he speaks does not 

 arise till, with each advancing step, a new and complicated 

 adjustment (which introduces the two new forms, each with 

 unabated fertility with its own kind but with diminished fer- 

 tility with the other kind) has been attained by some other 

 process. That other process is the one described in the pas- 

 sage I have already quoted from pp. 184-5, where, according 

 to my apprehension, the cause of divergence is more correctly 

 stated than it is in the passage now under consideration. In 

 the latter part of my paper on Divergent Evohttion through 

 Cumulative Segregation I have shown that the different kinds 

 of incompatibility, preventing complete fertility between incip- 

 ient species (and there called forms of Negative Segregation), 

 cannot arise except as accompaniments of Positive Segregation 

 in some form ; but that, having once arisen in connection with 

 partial Positive Segregation, they increase from generation to 

 generation by a law that is quite distinct from natural selection. 

 It was also shown that endowments only partially segregative (as, 

 for example, somewhat divergent habits of feeding), when not 

 concurrent with any forms of cross incompatibility, are liable to 

 be obliterated by crossing ; but, when associated with segregate 

 fertility and cross infertility, will increase from generation to 

 generation, even if the mongrels are as well adapted to the 

 environment as the pure forms. I at the same time called 

 attention to the fact that, when associated with some form of 

 partial positive segregation (as divergent habits of feeding, or 

 segregative sexual and social instincts), greater vigor, of pure 

 forms, as contrasted with the mongrels, would have the same 

 effect as their greater fertility. In other words, Segregate 

 Vigor would preserve a partially segregated variety as effectual 

 as Segregate Fecundity. 



