368 EVOLUTION [CHAP. V 



Letter 279 allied geographical races or close species, seemed to me a 

 greater difficulty when I discussed the subject in the Origin. 



With respect to your illustration, it formerly drove me 

 half mad to attempt to account for the increase or diminution 

 of the productiveness of an organism ; but I cannot call to 

 mind where my difficulty lay. 1 Natural Selection always 

 applies, as I think, to each individual and its offspring, such 

 as its seeds, eggs, which are formed by the mother, and which 

 are protected in various ways. 2 There does not seem any 

 difficulty in understanding how the productiveness of an 

 organism might be increased ; but it was, as far as I can 

 remember, in reducing productiveness that I was most 

 puzzled. But why I scribble about this I know not. 



I have read your review of Mr. Allen's book, 3 and it 

 makes me more doubtful, even, than I was before whether he 

 has really thrown much light on the subject. 



I am glad to hear that some physiologists take the same 

 view as I did about your giving 4 too much credit to H. 

 Spencer though, heaven knows, this is a rare fault. 



The more I think of your medusa-nerve-work the more 

 splendid it seems to me. 



Letter 280 To A. De Candolle. 



Down, August 3rd, 1877. 



I must have the pleasure of thanking you for your long 

 and interesting letter. The cause and means of the transition 

 from an hermaphrodite to a unisexual condition seems to me 

 a very perplexing problem, and I shall be extremely glad to 



1 See Letters 209-16. 



It was in regard to this point that Romanes had sent the MS. to 

 Darwin. In a letter of June i6th he writes : " It was with reference to 

 the possibility of Natural Selection acting on organic types as dis- 

 tinguished from individuals, a possibility which you once told me did 

 not seem at all clear." 



3 See Nature (June 7th, 1877, p. 98), a review of Grant Allen's 

 Physiological Esthetics. 



4 The reference is to Romanes' lecture on Medusa, given at the 

 Royal Institution, May 25th. (See Nature, XVI., pp. 231, 269, 289.) It 

 appears from a letter of Romanes (June 6th) that it was the abstract 

 in the Times that gave the impression referred to. References to Mr. 

 Spencer's theories of nerve-genesis occur in Nature, pp. 232, 271, 289. 



