334 MY LIFE 



although ID his Idler to Darwin he had declared that his 

 mental questions had been answered. 



But a cause of difference on a scientific question had since 

 arisen between Romanes and myself which led to complica- 

 tion. In 1886 he read a paper to the Linnaan Society, which 



was printed in their Journal, entitled " Physiological Selection: 



an additional suggestion on the ( )rigin of Species." This 

 paper put forth what was really a new theory of the origin 



of infertile races, which was supposed to account for the 

 infertility that so generally occurs between allied species. It 

 was very complex, and led to much discussion, and before 

 leaving for America I had criticized it in the September 

 issue of the Fortnightly Reviczv. Later, I gave what I con- 

 sidered a proof of its entire fallacy in my " Darwinism " 

 (published in 1889), and many other writers had also given 

 reasons for rejecting it. This rejection of a theory which he 

 evidently thought very highly of seems to have been very 

 unexpected and to have somewhat ruffled his temper, as was 

 very natural, or he would not, I think, have written of me as 

 he did, especially if we consider the letters he had sent me four 

 years previously. In an article in the Nineteenth Century, 

 of May, 1890, he repeats a statement which he had made 

 before in other periodicals in the following words : — " He 

 presents an alternative theory to explain the same class of 

 facts. Yet this theory is purely and simply without any 

 modification whatsoever, a restatement of the first principles 

 of physiological selection, as these were originally stated by 

 myself." To this and to a repetition of it in the American 

 magazine, The Monist, of October, I replied in Nature, and 

 I need only say here that the essential parts of my theory 

 were founded partly on facts established by Darwin, and partly 

 on a mathematical demonstration that sterility could be in- 

 creased by natural selection. This last argument was stated 

 by me in nearly the same form in letters to Darwin in 1868, 

 eighteen years before Romanes set forth his theory of phys- 

 iological selection (see " More Letters of Charles Darwin," 

 vol. i. pp. 288-297). Further, while this last theory has now, 

 I believe, no supporters, my own view, so far as I know, has 



