1 868.] AND SELF-FERTILISATION.' 29 1 



from the crossed seed exactly twice as tall as the seedlings 

 from the self-fertilised seed ; both seeds having germinated 

 on same day. If I can establish this fact (but perhaps it will 

 all go to the dogs), in some fifty cases, with plants of different 

 orders, I think it will be very important, for then we shall 

 positively know why the structure of every flower permits, or 

 favours, or necessitates an occasional cross with a distinct 

 individual. But all this is rather cooking my hare before I 

 have caught it. But somehow it is a great pleasure to me to 

 tell you what I am about. 



Believe me, my dear Gray, 

 Ever yours most truly, and with cordial thanks, 



Ch. Darwin. 



C. Darwin to G. Bentham. 



April 22, 1868. 



.... I am experimenting on a very large scale on the 

 difference in power of growth between plants raised from 

 self-fertilised and crossed seeds ; and it is no exaggeration to 

 say that the difference in growth and vigour is sometimes 

 truly wonderful. Lyell, Huxley and Hooker have seen 

 some of my plants, and been astonished ; and I should much 

 like to show them to you. I always supposed until lately 

 that no evil effects would be visible until after several genera- 

 tions of self-fertilisation ; but now I see that one generation 

 sometimes suffices ; and the existence of dimorphic plants 

 and all the wonderful contrivances of orchids are quite 

 intelligible to me. 



With cordial thanks for your letter, which has pleased me 



greatly, 



Yours very sincerely, 



Charles Darwin. 



[An extract from a letter to Dr. Gray (March 11, 1873) 

 mentions the progress of the work : — 



U 2 



