The Wallace-Darwin Correspondence 



islands there are cases of identity, which I cannot at 

 present persuade myself to account for by introduction 

 through man's agency; although Dr. Aug. Gould has con- 

 clusively shown that many land- shells have thus been dis- 

 tributed over the Pacific by man's agency. These cases of 

 introduction are most plaguing. Have you not found it so 

 in the Malay Archipelago? It has seemed to me, in the 

 lists of mammals of Timor and other islands, that several 

 in all probability have been naturalised. 



Since writing before, I have experimented a little on 

 some land-molluscs, and have found sea-water not quite so 

 deadly as I anticipated. You ask whether I shall discuss 

 Man : I think I shall avoid the whole subject, as so sur- 

 rounded with prejudices, though I fully admit that it is 

 the highest and most interesting problem for the naturalist. 

 My work, on which I have now been at work more or less 

 for twenty years, will not fix or settle anything ; but I hope 

 it will aid by giving a large collection of facts with one 

 definite end. I get on very slowly, partly from ill-health, 

 partly from being a very slow worker. I have got about 

 half written; but I do not suppose I shall publish under 

 a couple of years. I have now been three whole months on 

 one chapter on hybridism ! 



I am astonished to see that you expect to remain out 

 three or four years more : what a wonderful deal you will 

 have seen; and what an interesting area, the grand Malay 

 Archipelago and the richest parts of South America! I 

 infinitely admire and honour your zeal and courage in the 

 good cause of natural science ; and you have my very sincere 

 and cordial good wishes for success of all kinds ; and may all 

 your theories succeed, except that on oceanic islands, on 

 which subject I will do battle to the death. — Pray believe 

 me, my dear Sir, yours very sincerely, q^ Darwin. 



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