272 THE 'ORIGIN OF SPECIES.' [i860. 



It naturally happens that my review of your book does not 

 exhibit anything like the full force of the impression the book 

 has made upon me. Under the circumstances I suppose I do 

 your theory more good here, by bespeaking for it a fair and 

 favourable consideration, and by standing non-committed as 

 to its full conclusions, than I should if I announced myself a 

 convert ; nor could I say the latter, with truth. 



Well, what seems to me the weakest point in the book is 

 the attempt to account for the formation of organs, the making 

 of eyes, &c., by natural selection. Some of this reads quite 

 Lamarckian. 



The chapter on Hybridism is not a weak, but a strong' 

 chapter. You have done wonders there. But still you have 

 not accounted, as you may be held to account, for divergence 

 up to a certain extent producing increased fertility, of the 

 crosses, but carried one short almost imperceptible step more, 

 giving rise to sterility, or reversing the tendency. Very likely 

 you are on the right track ; but you have something to do yet 

 in that department. 



Enough for the present. 



I am not insensible to your compliments, the very 



high compliment which you pay me in valuing my opinion. 

 You evidently think more of it than I do, though from the 

 way I write [to] you, and especially [to] Hooker, this might 

 not be inferred from the reading of my letters. 



I am free to say that I never learnt so much from one book 

 as I have from yours. There remain a thousand things I long 



to say about it. 



Ever yours, 



ASA GRAY. 



C. Darwin to Asa Gray, 



[February? 1860.] 



Now I will just run through some points in your 



letter. What you say about my book gratifies me most deeply 





