172 GEOEGE JOHN EOMANBS issi- 



run. Then, whether the results prove positive or 

 negative, it will not be open for any one to doubt 

 them on the ground of any fault in the method. 



Do any objections occur to you re my answer to 

 critics in the ' Nineteenth Century ' ? Of course I 

 might have said more about the swamping effects of 

 free intercrossing (which appears to me the only 

 point in which I deviate at all from the ' Origin of 

 Species '), but it is much too large a subject to be 

 dealt with in a review. My greatest difficulty here 

 is to conceive the possibility of difierentiation (as 

 distinguished from transmutation in Hnear series) 

 without the assistance of isolation in some form or 

 another. 



Yours very truly, 



Geo. J. EoMANEs. 



Dear Darwin, — Criticism of an intelhgent kind is 

 what I feel most in need of, and therefore it is no 

 merit on my part to like it when it comes. 



The point about the combined action of natural 

 and physiological selection is, after all, a very sub- 

 ordinate one, and, as I said in ' Nature ' some weeks 

 ago, is the most highly speculative and least trust- 

 worthy part of the theory. Moreover, it is the only 

 part that is directly opposed to an expressed conclusion 

 in the ' Origin,' though, even here, the opposition 

 is not real. If natural selection can do anything 

 at all in the way of bringing about sterility with 

 parent forms, it can only do so by acting on the type 

 or whole community (for I quite agree with the 

 reasoning in the ' Origin,' that it cannot do so by 



