this doctrine, it has been eagerly followed; and Hooker elaborately discusses the former connection of all the Antarctic islands and New Zealand and South America.  About a year ago I discussed the subject much with Lyell and Hooker (for I shall have to treat of it) and wrote out my arguments in opposition; but you will be glad to hear that neither Lyell nor Hooker thought much of my arguments; nevertheless, for once in my life I dare withstand the almost preternatural sagacity of Lyell.  You ask about land-shells on islands far distant from continents:  Madeira has a few identical with those of Europe, and here the evidence is really good, as some of them are sub-fossil.  In the Pacific 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 conclusively shown that many land-shells have thus been distributed 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 surrounded 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,

C. DARWIN.

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LETTER III

C. DARWIN TO A.R.  WALLACE

Down, Bromley, Kent.  January 25, 1859.