3H EVOLUTION [Chap. IV 



Letter 229 against Huxley and for Thomson. This review shows me — 

 not that I required being shown — how devilish a clever fellow 

 Huxley is, for the reviewer cannot help admiring his abilities. 

 There are some good specimens of mathematical arrogance in 

 the review, and incidentally he shows how often astronomers 

 have arrived at conclusions which are now seen to be mis- 

 taken ; so that geologists might truly answer that we must 

 be slow in admitting your conclusions. Nevertheless, all 

 uniformitarians had better at once cry " peccavi," — not but 

 what I feel a conviction that the world will be found rather 

 older than Thomson makes it, and far older than the reviewer 

 makes it. I am glad I have faced and admitted the difficulty 

 in the last edition of the Origin, of which I suppose you 

 received, according to order, a copy. 



Letter 230 To J. D. Hooker. 



Down, Aug. 7th [1S69]. 



There never was such a good man as you for telling me 

 things which I like to hear. I am not at all surprised that 

 Hallett has found some varieties of wheat could not be 

 improved in certain desirable qualities as quickly as at first. 

 All experience shows this with animals ; but it would, I think, 

 be rash to assume, judging from actual experience, that a 

 little more improvement could not be got in the course of 

 a century, and theoretically very improbable that after a few 

 thousands [of years] rest there would not be a start in the 

 same line of variation. What astonishes me as against 

 experience, and what I cannot believe, is that varieties 

 already improved or modified do not vary in other respects. 

 I think he must have generalised from two or three spon- 

 taneously fixed varieties. Even in seedlings from the same 

 capsule some vary much more than others ; so it is with 

 sub-varieties and varieties. 1 



It is a grand fact about AnoplotJicrinni? and shows how 



1 In a letter of August 13th, 1869, Sir J. D. Hooker wrote correcting 

 Mr. Darwin's impression : " I did not mean to imply that Hallett affirmed 

 that all variation stopped — far from it : he maintained the contrary, but if 

 I understand him aright, he soon arrives at a point beyond which any 

 further accumulation in the direction sought is so small and so slow that 

 practically a fixity of type (not absolute fixity, however) is the result." 



1 This perhaps refers to the existence of Anoplothcrium in the S. 



