George has been explaining our differences. I have admitted in the new edition (273/1. In the second edition (1875) of the "Variation of Animals and Plants," Volume II., page 350, reference is made to Mr. Galton's transfusion experiments, "Proc. R. Soc." XIX., page 393; also to Mr. Galton's letter to "Nature," April 27th, 1871, page 502. This is a curious mistake; the letter in "Nature," April 27th, 1871, is by Darwin himself, and refers chiefly to the question whether gemmules may be supposed to be in the blood. Mr. Galton's letter is in "Nature," May 4th, 1871, Volume IV., page 5. See Letter 235.) (before seeing your essay) that perhaps the gemmules are largely multiplied in the reproductive organs; but this does not make me doubt that each unit of the whole system also sends forth its gemmules. You will no doubt have thought of the following objection to your views, and I should like to hear what your answer is. If two plants are crossed, it often, or rather generally, happens that every part of stem, leaf, even to the hairs, and flowers of the hybrid are intermediate in character; and this hybrid will produce by buds millions on millions of other buds all exactly reproducing the intermediate character. I cannot doubt that every unit of the hybrid is hybridised and sends forth hybridised gemmules. Here we have nothing to do with the reproductive organs. There can hardly be a doubt from what we know that the same thing would occur with all those animals which are capable of budding, and some of these (as the compound Ascidians) are sufficiently complex and highly organised.
LETTER 274. TO LAWSON TAIT. March 25th, 1876.
(274/1. The reference is to the theory put forward in the first edition of "Variation of Animals and Plants," II., page 15, that the asserted tendency to regeneration after the amputation of supernumerary digits in man is a return to the recuperative powers characteristic of a "lowly organised progenitor provided with more than five digits." Darwin's recantation is at Volume I., page 459 of the second edition.)
Since reading your first article (274/2. Lawson Tait wrote two notices on "The Variation of Animals and Plants under Domestication" in the "Spectator" of March 4th, 1876, page 312, and March 25th, page 406.), Dr. Rudinger has written to me and sent me an essay, in which he gives the results of the MOST EXTENSIVE inquiries from all eminent surgeons in Germany, and all are unanimous about non-growth of extra digits after amputation. They explain some apparent cases, as Paget did to me. By the way, I struck out of my second edition a quotation from Sir J. Simpson about re-growth in the womb, as Paget demurred, and as I could not say how a rudiment of a limb due to any cause could be distinguished from an imperfect re-growth. Two or three days ago I had another letter from Germany from a good naturalist, Dr. Kollmann (274/3. Dr. Kollmann was Secretary of the Anthropologische Gesellschaft of Munich, in which Society took place the discussion referred to in "Variation of Animals and Plants," I., 459, as originating Darwin's doubts on the whole question. The fresh evidence adduced by Kollmann as to the normal occurrence of a rudimentary sixth digit in Batrachians is Borus' paper, "Die sechste Zehe der Anuren" in "Morpholog. Jahrbuch," Bd. I., page 435. On this subject see Letter 178.), saying he was sorry that I had given up atavism and extra digits, and telling me of new and good evidence of rudiments of a rudimentary sixth digit in Batrachians (which I had myself seen, but given up owing to Gegenbaur's views); but, with re-growth failing me, I could not uphold my old notion.
(275/1. Mr. Romanes' reply to this letter is printed in his "Life and Letters," page 93, where by an oversight it is dated 1880-81.)
H. Wedgwood, Esq., Hopedene, Dorking, May 29th .
As you are interested in pangenesis, and will some day, I hope, convert an "airy nothing" into a substantial theory, I send by this post an essay by Hackel (275/2. "Die Perigenesis der Plastidule oder die Wellenzeugung der Lebenstheilchen," 79 pages. Berlin, 1876.) attacking Pan. and substituting a molecular hypothesis. If I understand his views rightly, he would say that with a bird which strengthened its wings by use, the formative protoplasm of the strengthened parts became changed, and its molecular vibrations consequently changed, and that these vibrations are transmitted throughout the whole frame of the bird, and affect the sexual elements in such a manner that the wings of the offspring are developed in a like strengthened manner. I imagine he would say, in cases like those of Lord Morton's mare (275/3. A nearly pure-bred Arabian chestnut mare bore a hybrid to a quagga, and subsequently produced two striped colts by a black Arabian horse: see "Animals and Plants," I., page 403. The case was originally described in the "Philosophical Transactions," 1821, page 20. For an account of recent work bearing on this question, see article on "Zebras, Horses, and Hybrids," in the "Quarterly Review," October 1899. See Letter 235.), that the vibrations from the protoplasm, or "plasson," of the seminal fluid of the zebra set plasson vibrating in the mare; and that these vibrations continued until the hair of the second colt was formed, and which consequently became barred like that of a zebra. How he explains reversion to a remote ancestor, I know not. Perhaps I have misunderstood him, though I have skimmed the whole with some care. He lays much stress on inheritance being a form of unconscious memory, but how far this is part of his molecular vibration, I do not understand. His views make nothing clearer to me; but this may be my fault. No one, I presume, would doubt about molecular movements of some kind. His essay is clever and striking. If you read it (but you must not on my account), I should much like to hear your judgment, and you can return it at any time. The blue lines are Hackel's to call my attention.
We have come here for rest for me, which I have much needed; and shall remain here for about ten days more, and then home to work, which is my sole pleasure in life. I hope your splendid Medusa work and your experiments on pangenesis are going on well. I heard from my son Frank yesterday that he was feverish with a cold, and could not dine with the physiologists, which I am very sorry for, as I should have heard what they think about the new Bill. I see that you are one of the secretaries to this young Society.