i859— 1863] VARIATION 199 



To J. D. Hooker. Letter 136 



26th [March, 1S62]. 



Thanks also for your own 1 and Bates' letter now returned. 

 They are both excellent ; you have, I think, said all that can 

 be said against direct effects of conditions, and capitally put. 

 But I still stick to my own and Bates' side. Nevertheless I 

 am pleased to attribute little to conditions, and I wish I had 

 done what you suggest — started on the fundamental principle 

 of variation being an innate principle, and afterwards made a 

 few remarks showing that hereafter, perhaps, this principle 

 would be explicable. Whenever my book on poultry, pigeons, 

 ducks, and rabbits is published, with all the measurements 

 and weighings of bones, I think you will see that " use and 

 disuse " at least have some effect. I do not believe in perfect 

 reversion. I rather demur to your doctrine of " centrifugal 

 variation." 2 I suppose you do not agree with or do not 

 remember my doctrine of the good of diversification 3 ; this 

 seems to me amply to account for variation being centrifugal 

 — if you forget it, look at this discussion (p. 117 of 3rd £dit.), 

 it was the best point which, according to my notions, I made 

 out, and it has always pleased me. It is really curiously satis- 

 factory to me to see so able a man as Bates (and yourself) 

 believing more fully in Natural Selection than I think I even 

 do myself. 1 By the way, I always boast to you, and so I 



1 See note 1 in Letter 135. 



2 The "doctrine of centrifugal variation" is given in Sir J. D. Hooker's 

 Introductory Essay to the Flora of Tasmania (Part III. of the Botany of 

 the Antarctic Expedition), 1859, p. viii. In paragraph 10 the author writes: 

 " The tendency of varieties, both in nature and under cultivation .... 

 is rather to depart more and more widely from the original type than to 

 revert to it." In Sir Joseph's letter to Bates {Joe. cit., p. lii) he wrote : 

 " Darwin also believes in some reversion to type which is opposed 

 to my view of variation." It may be noted in this connection that 

 Mr. Galton has shown reason to believe in a centripetal tendency in 

 variation (to use Hooker's phraseology) which is not identical with 

 the reversion of cultivated plants to their ancestors, the case to which 

 Hooker apparently refers. See Natural Inheritance, by F. Galton, 1889. 



3 Darwin usually used the word "divergence" in this connection. 



1 This refers to a very interesting passage in Hooker's letter to Bates 

 {Joe. cit., p. liii) : " I am sure that with you, as with me, the more you 

 think the less occasion you will see for anything but time and natural 

 selection to effect change ; and that this view is the simplest and clearest 



