234 EVOLUTION [CHAP. Ill 



Letter 160 but you have the art of making subjects, which might be dry, 

 run easily. I have been fairly astonished at the amount of 

 individual variability in the oaks. I never saw before the 

 subject in any department of nature worked out so carefully. 

 What labour it must have cost you ! You spoke in one letter 

 of advancing years ; but I am very sure that no one would 

 have suspected that you felt this. I have been interested 

 with every part ; though I am so unfortunate as to differ 

 from most of my contemporaries in thinking that the vast 

 continental extensions 1 of Forbes, Heer, and others are not 

 only advanced without sufficient evidence, but are opposed to 

 much weighty evidence. You refer to my work in the kindest 

 and most generous spirit. I am fully satisfied at the length 

 in belief to which you go, and not at all surprised at the 

 prudent reservations which you make. I remember well how 

 many years it cost me to go round from old beliefs. It is en- 

 couraging to me to observe that everyone who has gone an 

 inch with me, after a period goes a few more inches or even 

 feet. But the great point, as it seems to me, is to give up 

 the immutability of specific forms ; as long as they are thought 

 immutable, there can be no real progress in " Epiontology " 2 

 It matters very little to any one except myself, whether I am 

 a little more or less wrong on this or that point ; in fact, I 

 am sure to be proved wrong in many points. But the subject 

 will have, I am convinced, a grand future. Considering that 

 birds are the most isolated group in the animal kingdom, 

 what a splendid case is this Solenhofen bird-creature with its 

 long tail and fingers to its wings ! I have lately been daily 

 and hourly using and quoting your Geographical Botany in 

 my book on Variation under Domestication. 



Letter 161 To Horace Dobell. 



Down, Feb. i6th [1863]. 



Absence from home and consequent idleness are the 

 causes that I have not sooner thanked you for your very 



1 See Letters 47, 48. 



3 See De Candolle, loc. cit., p. 67 : he defines " Epiontologie " as the 

 study of the distribution and succession of organised beings from their 

 origin up to the present time. At present Epiontology is divided into 

 geography and palaeontology, " mais cette division trop inegale et a 

 limites bien vagues disparaitra probablement." 



