2 62 'VARIATION UNDER DOMESTICATION.' [1868. 



forming a judgment (excepting partly Quatrefages), who 

 seems to have thought anything of this part of my work. 

 The amount of labour, correspondence, and care, which the 

 subject cost me, is more than you could well suppose. I 

 thought the article in the Atheruzum was very unjust ; but 

 now I feel amply repaid, and I cordially thank you for your 

 sympathy and too warm praise. What labour you have 

 bestowed on your part of the ' Record ' ! I ought to be 

 ashamed to speak of my amount of work. I thoroughly 

 enjoyed the Sunday, ^vhich you and the others spent here, 



and 



I remain, dear Newton, yours very sincerely, 



CH. DARWIN. 



C. Darwin to A. R. Wallace. 



Down, February 27 [1868]; 



MY DEAR WALLACE, You cannot well imagine how much 

 I have been pleased by what you say about ' Pan genesis/ 

 None of my friends will speak out. . . . Hooker, as far as I 

 understand him, which I hardly do at present, seems to 

 think that the hypothesis is little more than saying that 

 organisms have such and such potentialities. What you 

 say exactly and fully expresses my feeling, viz. that it is a 

 relief to have some feasible explanation of the various facts, 

 which can be given up as soon as any better hypothesis is 

 found. It has certainly been an immense relief to my mind ; 

 for I have been stumbling over the subject for years, dimly 

 seeing that some relation existed between the various classes 

 of facls. I now hear from H. Spencer that his views quoted 

 in my foot-note refer to something quite distinct, as you 

 seem to have perceived. 



I shall be very glad to hear at some future day your criti- 

 cisms on the " causes of variability." Indeed I feel sure that 

 I am right about sterility and natural selection. ... I do not 

 quite understand your case, and we think that a word or two 

 is misplaced. I wish sometime you would consider the case 

 under the following point of view : If sterility is caused or 



