Appendix B. 159 



founded. Nevertheless, for the sake of meeting these 

 criticisms upon their own ground, I will endeavour to show 

 that, even as mathematical calculations, they are quite un- 

 trustworthy. And, in order to do this effectually, I will quote 

 the results of a much more competent, as well as a much more 

 thorough, inquiry. I applied to Mr. Moulton for this 

 purpose, not only because he is one of the ablest mathe- 

 maticians of my acquaintance ; but also because his interest 

 in biology, and his knowledge of Darwinian literature, 

 render him well fitted to appreciate exactly, and in all their 

 bearings, the questions which were submitted to his con- 

 sideration. I need only add that his examination was 

 completely independent, and in no way influenced by me. 

 Having previously read my paper on Physiological Selection, 

 Mr. Gulick's paper on Divergent Evolution, and Mr. Wallace's 

 book on Darwinism, he was in possession of all the materials ; 

 and I merely requested the favour of his opinion upon the 

 whole case from a mathematical point of view. The 

 following is his reply ; and I give it in extenso, because it 

 serves to place in another light some of the general considera- 

 tions which it has already been my endeavour to present 1 . 



After some introductory remarks on Mr. Wallace's 

 " adoption of the theory of physiological selection pure 

 and simple," and "the pure caricature of it which he 

 puts forward as" mine, the letter proceeds thus: 



The reason why it is so easy to attack your theory is that 

 it is so easy to confuse the survival of an individual with the 



1 In our Nature correspondence of 1890-1891, Mr. Wallace remarked : 

 " If Dr. Romanes will carefully work out numerically (as I have 

 attempted to do) a few cases showing the preservative and accumulative 

 agency of pure physiological selection within an otherwise undifferentiated 

 species, he will do more for his theory than volumes of general disquisi- 

 tion or any number of assertions that it does possess this power." 

 Several months before this was written I had already in my hands 

 Mr. Moulton's letter, with its accompanying calculations. 



