ch. x.] 18431858. 189 



pleased. ... I am particularly obliged to you for sending 

 me Asa Gray's letter ; how very pleasantly he writes. To 

 see his and your caution on the species-question ought to 

 overwhelm me in confusion and shame ; it does make me 

 feel deuced uncomfortable. ... I was pleased and surprised 

 to see A. Gray's remarks on crossing obliterating varieties, 

 on which, as you know, I have been collecting facts for 

 these dozen years. How awfully flat I shall feel, if, when I 

 get my notes together on species, &c. &c, the whole thing 

 explodes like an empty puff-ball. Do not work yourself to 

 death. Ever yours most truly. 



To work out the problem of the Geographical Distribution 

 of animals and plants on evolutionary principles, Darwin 

 had to study the means by which seeds, eggs, &c, can be 

 transported across wide spaces of ocean. It was this need 

 which gave an interest to the class of experiment to which 

 the following letters refer. 



C. D. to J. D. Hooker. April 13th [1855]. 



... I have had one experiment some little time in 

 progress which will, I think, be interesting, namely, seeds 

 in salt water, immersed in water of 32-33 , which I have 

 and shall long have, as I filled a great tank with snow. 

 When I wrote last I was going to triumph over you, for my 

 experiment had in a slight degree succeeded ; but this, with 

 infinite baseness, I did not tell, in hopes that you would say 

 that you would eat all the plants which I could raise after 

 immersion. It is very aggravating that I cannot in the 

 least remember what you did formerly say that made me 

 think you scoffed at the experiments vastly ; for you now 

 seem to view the experiment like a good Christian. I have 

 in small bottles out of doors, exposed to variation of tem- 

 perature, cress, radish, cabbages, lettuces, carrots, and celery, 

 and onion seed. These, after immersion for exactly one 

 week, have all germinated, which I did not in the least ex- 

 pect (and thought how you would sneer at me) ; for the 

 water of nearly all, and of the cress especially, smelt very 

 badly, and the cress seed emitted a wonderful quantity of 

 mucus (the Vestiges * would have expected them to turn 

 into tadpoles), so as to adhere in a mass ; but these seeds 



* The Vestiges of Creation, by K. Chambers. 



