THEOUGH CUMULATIVE SEaREGATION. 



199 



genera not otherwise segregated would not have stood in the 

 way of their becoming different families, and that therefore 

 mutual sterility has had nothing to do with their continued 

 divergence ; still he seems to have failed to perceive the im- 

 portant influence this principle must have had on the divergent 

 evolution of the higher groups of organisms. 



The correspondences in the two papers are notwithstanding 

 more remarkable than the differences. Of these, the most conspi- 

 cuous is the use of the word Segregation to express the principle 

 under consideration.* As I have already pointed out, I used this 

 word for the same purpose in an article in the ' Chrysanthemum,' 

 published in January 1883 ; and again in the ' Chinese Eecorder ' 

 for July 1885, where I spoke of the " Law of Segregation rising 

 out of the very nature of organic activities, bringing together those 

 similarly endowed," and causing " the division of the survivors 

 of one stock, occupying one country, into forms diff'ering more 

 and more widely from each other." 



I trust that my discussion of the various forms of Segregation, 

 both Negative and Positive, though presented in so condensed a 

 form, will throw light on the subject of the mutual sterility of 

 species ; and that in other ways my presentation of the subject 

 will contribute something, not only to the theory of Physio- 

 logical Segregation, but to other branches of the general theory 

 of evolution. 



I should here acknowledge (what will, I think, be manifest on 

 every page of my paper) that my obligations to Darwin and 

 Wallace are far greater than are indicated by quotations and 

 references. 



I very much regret that I have failed of obtaining a copy of 

 ' Evolution without Natural Selection,' by Charles Dixon ; but, 

 from his letter in ' Nature,' vol. xxxiii. p. 100, 1 see that he main- 

 tains " That isolation can preserve a non-beneficial variation as 

 effectually as natural selection can preserve a beneficial variation." 

 He does not there refer to the fact, which I emphasize, that all 

 divergence of a permanent character, whether beneficial or non- 

 beneficial, is dependent on Segeneration either Separative or 

 Segregative. 



* See paper on "Physiological Selection," Linn. Soc. Journ., Zoology, 

 vol. xix. pp.354, 356, 391, 395. 



