Appendix B. 161 



selective fertility would be so fatal to individuals that no type 

 which presents it could be formed or perpetuated a conclu- 

 sion which is not only absurd in itself, but contradicted by 

 his own subsequent adoption of your theory. Besides, apart 

 from calculations (with which I will deal when I write next), 

 such reasoning brings its own refutation. Selective fertility is 

 not in the same category as some of the other influences to 

 which an important share has been ascribed in the formation 

 of the existing types. // exists as a recognized phenomenon. 

 Hence all these numerical proofs that it would lead to extinc- 

 tion, because it is so disadvantageous to the possessor, prove 

 too much. They would show that the degree of selective 

 fertility which so frequently characterizes species is a most 

 onerous gift ; and that, were it not present, there would be 

 a vastly increased chance of fertility, which would render the 

 races fitter and lead to their increased survival. Why then 

 has it not been got rid of? 



The two answers which no doubt would be given seem to 

 me to support rather than to make against your theory. In 

 the first place, Wallace might say that this infertility is an 

 advantage because it keeps pure a type which is specially 

 fitted to its surroundings, as shown by its continued existence. 

 But if this be so, and it is necessary to protect the developed 

 type, how much more necessary to protect the incipient type ! 

 In the second place, he might say that this selective fertility 

 is not so disadvantageous when the species has been formed, 

 because the individual can choose his mate from his like ; 

 whereas, when it is beginning to be formed, he must mate 

 blindly, or without what you call " psychological selection.'' 

 But this seems to me to be wholly inapplicable to at least half 

 the animal, and to all the vegetable kingdom. Moreover, with re- 

 gard to the other half of the animal kingdom, it merely raises the 

 question, How soon will such an incipient type recognize itself? 

 Seeing it is probable that many families [broods] will belong to 

 the same [incipient] type, I should not be surprised if it were 

 found that this sexual recognition and preference sets in very 

 early. 



But this leads me to the question of your letter. I under- 

 stand you to want me to examine and criticize the attempted 



III. M 



