56 GEOEGE JOHN EOMANES 1876- 



the marked difference in the behaviour of the 

 rabbits and the guinea-pigs points to inherited experi- 

 ence on the part of the former which is absent in the 

 case of the latter ? If nettles are not endemic in 

 South America, this inference would seem almost 

 irresistible. Dr. Hooker tells me nettles grow there 

 now, but he does not know whether they did so before 

 America was visited by Europeans. Possibly there 

 might be some way of ascertaining. 



I have now made a number of grafts at Kew. In 

 about a month, I should think, one could see which 

 are coming up as single and which as double sprouts. 

 If, therefore, Frank is going to work in the laboratory 

 in July, he might perhaps look over the bed (which 

 is just outside the door), and reject the double-stalked 

 specimens. I could trust him to do this better than 

 any one at Kew, and if the useless specimens were 

 rejected, there would afterwards be much less trouble 

 in protecting the valuable ones. But do not suggest 

 it unless you think it would be quite agreeable to 

 him. If he is in town within the next fortnight, I 

 wish he would look me up. 



June 16. 



I have deferred answering your letter until having 

 had a talk with Mr. Galton about rudimentary organs. 

 He thinks with me that if the normal size of a useful 

 organ is maintained in a species, when natural 

 selection is removed, the average size will tend to 

 become progressively reduced by inter-crossing, and 

 this down to whatever extent economy of growth 

 remains operative in placing a premium on variations 



