34 2 MISCELLANEOUS. [l88l. 



C. Darwin to F. Muller. 



Down, July 4 [1881]. 



MY DEAR SlR, Your kindness is unbounded, and I cannot 

 tell you how much your last letter (May 31) has interested 

 me. I have piles of notes about the effect of water resting on 

 leaves, and their movements (as I supposed) to shake off the 

 drops. But I have not looked over these notes for a long 

 time, and had come to think that perhaps my notion was mere 

 fancy, but I had intended to begin experimenting as soon as 

 I returned home ; and now with your invaluable letter about 

 the position of the leaves of various plants during rain (I have 

 one analogous case with Acacia from South Africa), I shall 

 be stimulated to work in earnest. 



VARIABILITY. 



[The following letter refers to a subject on which my father 

 felt the strongest interest : the experimental investigation of 

 the causes of variability. The experiments alluded to were 

 to some extent planned out, and some preliminary work was 

 begun in the direction indicated below, but the research was 

 ultimately abandoned.] 



C. Darwin to J. H. Gilbert* 



Down, February 16, 1876. 



MY DEAR SlR, When I met you at the Linnean Society, 

 you were so kind as to say that you would aid me with advice, 

 and this will be of the utmost value to me and my son. I will 

 first state my object, and hope that you will excuse a long 

 letter. It is admitted by all naturalists that no problem is so 

 perplexing as what causes almost every cultivated plant to 



* Dr. Gilbert, F.R.S., joint author long series of valuable researches 

 with Sir John Bennett Lawes of a in Scientific Agriculture. 



