I have begun to work steadily, but very slowly as usual, at details on variation under domestication. My dear Gray, Yours always truly and gratefully, C. DARWIN. CHARLES DARWIN TO C. LYELL. Down, [May 8th, 1860]. ... I have sent for the 'Canadian Naturalist.' If I cannot procure a copy I will borrow yours. I had a letter from Henslow this morning, who says that Sedgwick was, on last Monday night, to open a battery on me at the Cambridge Philosophical Society. Anyhow, I am much honoured by being attacked there, and at the Royal Society of Edinburgh. I do not think it worth while to contradict single cases nor is it worth while arguing against those who do not attend to what I state. A moment's reflection will show you that there must be (on our doctrine) large genera not varying (see page 56 on the subject, in the second edition of the 'Origin'). Though I do not there discuss the case in detail. It may be sheer bigotry for my own notions, but I prefer to the Atlantis, my notion of plants and animals having migrated from the Old to the New World, or conversely, when the climate was much hotter, by approximately the line of Behring's Straits. It is most important, as you say, to see living forms of plants going back so far in time. I wonder whether we shall ever discover the flora of the dry land of the coal period, and find it not so anomalous as the swamp or coal-making flora. I am working away over the blessed Pigeon Manuscript; but, from one cause or another, I get on very slowly... This morning I got a letter from the Academy of Natural Sciences of Philadelphia, announcing that I am elected a correspondent... It shows that some Naturalists there do not think me such a scientific profligate as many think me here. My dear Lyell, yours gratefully, C. DARWIN. P.S.--What a grand fact about the extinct stag's horn worked by man! CHARLES DARWIN TO J.D. HOOKER. Down, [May 13th, 1860]. My dear Hooker, I return Henslow, which I was very glad to see. How good of him to defend me. (Against Sedgwick's attack before the Cambridge Philosophical Society.) I will write and thank him. As you said you were curious to hear Thomson's (Dr. Thomas Thomson the Indian Botanist. He was a collaborateur in Hooker and Thomson's Flora Indica. 1855.) opinion, I send his kind letter. He is evidently a strong opposer to us... CHARLES DARWIN TO J.D. HOOKER. Down, [May 15th, 1860].