42 EVOLUTION [CHAP. II 



Letter 14 in distant parts of the world. In shells, I hope hereafter to 

 get much light on this question through fossils. If you can 

 help me, I should be very much obliged : indeed, all your 

 letters are most useful to me. 



Monday. Now for your first long letter, and to me quite 

 as interesting as long. Several things are quite new to me 

 in it viz., for one, your belief that there are more extra- 

 tropical than intra-tropical species. I see that my argument 

 from the Arctic regions is false, and I should not have tried 

 to argue against you, had I not fancied that you thought 

 that equability of climate was the direct cause of the creation 

 of a greater or lesser number of species. I see you call our 

 climate equable ; I should have thought it was the contrary. 

 Anyhow, the term is vague, and in England will depend 

 upon whether a person compares it with the United States 

 or Tierra del Fuego. In my Journal (p. 342) I see I state 

 that in South Chiloe, at a height of about 1,000 feet, the 

 forests had a Fuegian aspect : I distinctly recollect that at 

 the sea-level in the middle of Chiloe the forest had almost a 

 tropical aspect. I should like much to hear, if you make out, 

 whether the N. or S. boundaries of a plant are the most 

 restricted ; I should have expected that the S. would be, in 

 the temperate regions, from the number of antagonist species 

 being greater. N.B. Humboldt, when in London, told me 

 of some river l in N.E. Europe, on the opposite banks of which 

 the flora was, on the same soil and under same climate, 

 widely different ! 



I forget 2 my last letter, but it must have been a very silly 

 one, as it seems I gave my notion of the number of species 

 being in great degree governed by the degree to which the 

 area had been often isolated and divided. I must have been 

 cracked to have written it, for I have no evidence, without a 

 person be willing to admit all my views, and then it does 

 follow. 



The remainder of the foregoing letter is published in the Life and 

 Letters, II., p. 29. It is interesting as giving his views on the mutability 



1 The Obi (see Flora Antarctica, p. 211, note). Hooker writes: 

 " Some of the most conspicuous trees attain either of its banks, but do 

 not cross them.' ; 



2 The last paragraph is published in Life and Letters, II., p. 29. 



