My dear Wallace,--You allude in your note to several points which I should much enjoy discussing with you did time and strength permit. I know Dr. Seeman is a good botanist, but I most strongly advise you to show the list to Hooker before you make use of the materials in print. Hooker seems much overworked, and is now gone a tour, but I suppose you will be in town before very long, and could see him. The list is quite unintelligible to me; it is not pretended that the same species exist in the Sandwich Islands and Arctic regions; and as far as the genera are concerned, I know that in almost every one of them species inhabit such countries as Florida, North Africa, New Holland, etc. Therefore these, genera seem to me almost mundane, and their presence in the Sandwich Islands will not, as I suspect in my ignorance, show any relation to the Arctic regions. The Sandwich Islands, though I have never considered them much, have long been a sore perplexity to me: they are eminently oceanic in position and productions; they have long been separated from each other; and there are only slight signs of subsidence in the islets to the westward. I remember, however, speculating that there must have been some immigration during the glacial period from North America or Japan; but I cannot remember what my grounds were. Some of the plants, I think, show an affinity with Australia. I am very glad that you like Lyell's chapter on Oceanic Islands, for I thought it one of the best in the part which I have read. If you do not receive the big photo of me in due time, let me hear.--Yours very sincerely, CH. DARWIN. * * * * * The following refers to Wallace's article, "A Theory of Birds' Nests," in Andrew Murray's _Journal of Travel_, i. 73. He here treats in fuller detail the view already published in the _Westminster Review_ for July, 1867, p. 38. The rule which Wallace believes, with very few exceptions, to hold good is, "that when both sexes are of strikingly gay and conspicuous colours, the nest is ... such as to conceal the sitting bird; while, whenever there is a striking contrast of colours, the male being gay and conspicuous, the female dull and obscure, the nest is open and the sitting bird exposed to view." At this time Wallace allowed considerably more influence to _sexual_ selection (in combination with the need of protection) than in his later writings. See his letter to Darwin of July 23, 1877 (p. 298), which fixes the period at which the change in his views occurred. He finally rejected Darwin's theory that colours "have been developed by the preference of the females, the more ornamented males becoming the parents of each successive generation." (_See_ "Darwinism," 1889, p. 285.) _Down, Bromley, Kent, S.E. April 15, 1868._