Correspondence on Biology, etc. 



to another closely allied species ha« been brought about. 

 Those who want to begin by discussing the causes of change 

 from a dog to a seal, or from a cow to a whale, are not worth 

 arguing with, as they e^idently do not comprehend the 

 A, B. C of the theory. 



Darwin's ineradicable acceptance of the theory of heredity 

 of the effects of climate, use and disuse, food, etc., on the 

 individual led to much obscurity and fallacy in his argu- 

 ments, here and there. — Yours very sincerely, 



Alfred E. Wallace. 



To Prof. Poulton 



Parkstone, Dorset. February 14, 1897. 



My dear Poulton, — Thanks for copy of your British Asso- 

 ciation Address,* which I did not read in Nature, being very 

 busy just then. I have now read it with much pleasure, and 

 think it a very useful and excellent discussion that was much 

 needed. There is, however, one important error, I think, 

 which vitiates a vital part of the argument, and which 

 renders it possible so to reduce the time indicated by geology 

 as to render the accordance of Geology and Physics more easy 

 to effect. The error I allude to was made by Sir A. Greikie 

 in his Presidential Address' which you quote. Immediately 

 it appeared I wrote to him pointing it out, but he merely 

 acknowledged my letter, saying he would consider it. To me 

 it seems a most palpable and extraordinary blunder. The 

 error consists in taking the rate of deposition as the same 

 as the rate of denudation, whereas it is about twenty times 

 as great, perhaps much more — because the area of deposition 

 is at least twenty times less than that of denudation. In 

 order to equal the area of denudation, it would require that 



» Presidential Address in Section D of British Association, 1896, reprinted 

 in " Essays on Evolution," p. 1. 



• To the British Association at Edinbur^, 1892. 



71 



