Do not hurry over Asa Gray. He strikes me as one of the best reasoners and writers I ever read. He knows my book as well as I do myself.
LETTER 113. TO C. LYELL. 15, Marine Parade, Eastbourne, October 3rd [1860].
Your last letter has interested me much in many ways.
I enclose a letter of Wyman's which touches on brains. Wyman is mistaken in supposing that I did not know that the Cave-rat was an American form; I made special enquiries. He does not know that the eye of the Tucotuco was carefully dissected.
With respect to reviews by A. Gray. I thought of sending the Dialogue to the "Saturday Review" in a week's time or so, as they have lately discussed Design. (113/1. "Discussion between two Readers of Darwin's Treatise on the Origin of Species, upon its Natural Theology" ("Amer. Journ. Sci." Volume XXX, page 226, 1860). Reprinted in "Darwiniana," 1876, page 62. The article begins with the following question: "First Reader--Is Darwin's theory atheistic or pantheistic? Or does it tend to atheism or pantheism?" The discussion is closed by the Second Reader, who thus sums up his views: "Wherefore we may insist that, for all that yet appears, the argument for design, as presented by the natural theologians, is just as good now, if we accept Darwin's theory, as it was before the theory was promulgated; and that the sceptical juryman, who was about to join the other eleven in an unanimous verdict in favour of design, finds no good excuse for keeping the Court longer waiting.") I have sent the second, or August, "Atlantic" article to the "Annals and Mag. of Nat. History." (113/2. "Annals and Mag. Nat. Hist." Volume VI., pages 373-86, 1860. (From the "Atlantic Monthly," August, 1860.)) The copy which you have I want to send to Pictet, as I told A. Gray I would, thinking from what he said he would like this to be done. I doubt whether it would be possible to get the October number reprinted in this country; so that I am in no hurry at all for this.
I had a letter a few weeks ago from Symonds on the imperfection of the Geological Record, less clear and forcible than I expected. I answered him at length and very civilly, though I could hardly make out what he was driving at. He spoke about you in a way which it did me good to read.
I am extremely glad that you like A. Gray's reviews. How generous and unselfish he has been in all his labour! Are you not struck by his metaphors and similes? I have told him he is a poet and not a lawyer.
I should altogether doubt on turtles being converted into land tortoises on any one island. Remember how closely similar tortoises are on all continents, as well as islands; they must have all descended from one ancient progenitor, including the gigantic tortoise of the Himalaya.
I think you must be cautious in not running the convenient doctrine that only one species out of very many ever varies. Reflect on such cases as the fauna and flora of Europe, North America, and Japan, which are so similar, and yet which have a great majority of their species either specifically distinct, or forming well-marked races. We must in such cases incline to the belief that a multitude of species were once identically the same in all the three countries when under a warmer climate and more in connection; and have varied in all the three countries. I am inclined to believe that almost every species (as we see with nearly all our domestic productions) varies sufficiently for Natural Selection to pick out and accumulate new specific differences, under new organic and inorganic conditions of life, whenever a place is open in the polity of nature. But looking to a long lapse of time and to the whole world, or to large parts of the world, I believe only one or a few species of each large genus ultimately becomes victorious, and leaves modified descendants. To give an imaginary instance: the jay has become modified in the three countries into (I believe) three or four species; but the jay genus is not, apparently, so dominant a group as the crows; and in the long run probably all the jays will be exterminated and be replaced perhaps by some modified crows.