I received your interesting letter of November 5th some little time ago, and despatched immediately a copy of my "Journal of Researches." I fear you will think me troublesome in my offer; but have you the second German edition of the "Origin?" which is a translation, with additions, of the third English edition, and is, I think, considerably improved compared with the first edition. I have some spare copies which are of no use to me, and it would be a pleasure to me to send you one, if it would be of any use to you. You would never require to re-read the book, but you might wish to refer to some passage. I am particularly obliged for your photograph, for one likes to have a picture in one's mind of any one about whom one is interested. I have received and read with interest your paper on the sponge with horny spicula. (188/1. "Ueber Darwinella aurea, einen Schwamm mit sternformigen Hornnadeln."--"Archiv. Mikrosk. Anat." I., page 57, 1866.) Owing to ill-health, and being busy when formerly well, I have for some years neglected periodical scientific literature, and have lately been reading up, and have thus read translations of several of your papers; amongst which I have been particularly glad to read and see the drawings of the metamorphoses of Peneus. (188/2. "On the Metamorphoses of the Prawns," by Dr. Fritz Muller.--"Ann. Mag. Nat. Hist." Volume XIV., page 104 (with plate), 1864. Translated by W.S. Dallas from "Wiegmann's Archiv," 1863 (see also "Facts and Arguments for Darwin," passim, translated by W.S. Dallas: London, 1869).) This seems to me the most interesting discovery in embryology which has been made for years. I am much obliged to you for telling me a little of your plans for the future; what a strange, but to my taste interesting life you will lead when you retire to your estate on the Itajahy! You refer in your letter to the facts which Agassiz is collecting, against our views, on the Amazons. Though he has done so much for science, he seems to me so wild and paradoxical in all his views that I cannot regard his opinions as of any value. LETTER 189. TO A.R. WALLACE. Down, January 22nd, 1866.