I thank you sincerely for writing to me and for your very interesting letter. Your name has for very long been familiar to me, and I have heard of your zealous exertions in the cause of Natural History. But I did not know that you had worked with high philosophical questions before your mind. I have an old belief that a good observer really means a good theorist (118/1. For an opposite opinion, see Letter 13.), and I fully expect to find your observations most valuable. I am very sorry to hear that your health is shattered; but I trust under a healthy climate it may be restored. I can sympathise with you fully on this score, for I have had bad health for many years, and fear I shall ever remain a confirmed invalid. I am delighted to hear that you, with all your large practical knowledge of Natural History, anticipated me in many respects and concur with me. As you say, I have been thoroughly well attacked and reviled (especially by entomologists--Westwood, Wollaston, and A. Murray have all reviewed and sneered at me to their hearts' content), but I care nothing about their attacks; several really good judges go a long way with me, and I observe that all those who go some little way tend to go somewhat further. What a fine philosophical mind your friend Mr. Wallace has, and he has acted, in relation to me, like a true man with a noble spirit. I see by your letter that you have grappled with several of the most difficult problems, as it seems to me, in Natural History--such as the distinctions between the different kinds of varieties, representative species, etc. Perhaps I shall find some facts in your paper on intermediate varieties in intermediate regions, on which subject I have found remarkably little information. I cannot tell you how glad I am to hear that you have attended to the curious point of equatorial refrigeration. I quite agree that it must have been small; yet the more I go into that question the more convinced I feel that there was during the Glacial period some migration from north to south. The sketch in the "Origin" gives a very meagre account of my fuller MS. essay on this subject. I shall be particularly obliged for a copy of your paper when published (118/2. Probably a paper by Bates entitled "Contributions to an Insect Fauna of the Amazon Valley" ("Trans. Entomol. Soc." Volume V., page 335, 1858-61).); and if any suggestions occur to me (not that you require any) or questions, I will write and ask. I have at once to prepare a new edition of the "Origin," (118/3. Third Edition, March, 1861.), and I will do myself the pleasure of sending you a copy; but it will be only very slightly altered. Cases of neuter ants, divided into castes, with intermediate gradations (which I imagine are rare) interest me much. See "Origin" on the driver-ant, page 241 (please look at the passage.) LETTER 119. TO T.H. HUXLEY.