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ARGUMENT FROM DOMESTICATION.
paper * in the Annals, a year or more ago, I can plainly see that we have thought much alike and to a certain extent have come to similar conclusions. In regard to the Paper in the Annals, I agree to the truth of almost every word of your paper; and I dare say that you will agree with me that it is very rare to find oneself agreeing pretty closely with any theoretical paper; for it is lamentable how each man draws his own different conclusions from the very same facts. This summer will inake the 20th year (!) since I opened my first note-book, on the question how and in what way do species and varieties differ from each other. I am now preparing my work for publication, but I find the subject so very large, that though I have written many chapters, I do not suppose I shall go to press for two years. I have never heard how long you intend staying in the Malay Archipelago; I wish I might profit by the publication of your Travels there before my work appears, for no doubt you will reap a large harvest of facts. I have acted already in accordance with your advice of keeping domestic varieties, and those appearing in a state of nature, distinct ; but I have sometimes doubted of the wisdom of this, and therefore I am glad to be backed by your opinion. I must confess, however, I rather doubt the truth of the now very prevalent doctrine of all our domestic animals having descended from several wild stocks; though I do not doubt that it is so in some cases. I think there is rather better evidence on the sterility of hybrid animals than you seem to admit: and in regard to plants the collection of carefully recorded facts by Kölreuter and Gaertner (and Herbert,] is enormous. I most entirely agree with you on the little effects of “climatal conditions,” which one sees referred to ad nauseam in all books : I suppose some very little effect must be attributed to such influences, but I fully believe that they are very slight. It is really impossible to explain my views (in the compass of a letter), on the causes and means
* On the law that has regulated the introduction of new species.' Ann. Nat. Hist., 1855.
of variation in a state of nature ; but I have slowly adopted a distinct and tangible idea,—whether true or false others must judge ; for the firmest conviction of the truth of a doctrine by its author, seems, alas, not to be the slightest guarantee of truth!..
C. Darwin to J. D. Hooker.
Moor Park, Saturday (May 2nd, 1857). MY DEAR HOOKER,-You have shaved the hair of the Alpine plants pretty effectually. The case of the Anthyllis will make a "tie" with the believed case of Pyrenees plants becoming glabrous at low levels. If I do find that I have marked such facts, I will lay the evidence before you. I wonder how the belief could have originated! Was it through final causes to keep the plants warm? Falconer in talk coupled the two facts of woolly Alpine plants and mammals. How candidly and meekly you took my Jeremiad on your severity to second-class men. After I had sent it off, an ugly little voice asked me, once or twice, how much of my
noble defence of the poor in spirit and in fact, was owing to your having not seldom smashed favourite notions of my own. I silenced the ugly little voice with contempt, but it would whisper again and again. I sometimes despise myself as a poor compiler as heartily as you could do, though I do not despise my whole work, as I think there is enough known to lay a foundation for the discussion on the origin of species. I have been led to despise and laugh at myself as a compiler, for having put down that “Alpine plants have large flowers," and now perhaps I may write over these very words, “ Alpine plants have small or apetalous flowers !
C. Darwin to J. D. Hooker.
Down, (May) 16:h (1857). MY DEAR HOOKER,-You said, I hope honestly—that you did not dislike my asking questions on general points, you of course answering or not as time or inclination might
serve, I find in the animal kingdom that the proposition that any part or organ developed normally (i. e., not a monstrosity) in a species in any high or unusual degree, compared with the same part or organ in allied species, tends to be highiy variable. I cannot doubt this from my mass of collected facts. To give an instance, the Cross-bill is very abnormal in the structure of its bill compared with other allied Fringillidæ, and the beak is eminently variable. The Himantopus, remarkable from the wonderful length of its legs, is very variable in the length of its legs. I could give many most striking and curious illustrations in all classes, so many that I think it cannot be chance. But I have none in the vegetable kingdom, owing, as I believe, to my ignorance. If Nepenthes consisted of one or two species in a group with a pitcher developed, then I should have expected it to have been very variable ; but I do not consider Nepenthes a case in point, for when a whole genus or group has an organ, however anomalous, I do not expect it to be variable,-it is only when one or few species difer greatly in some one part or organ from the forms closely allied to it in all other respects, that I believe such part or organ to be highly variable. Will you turn this in your mind ? it is an important apparent law (:) for me.
P.S. I do not know how far you will care to hear, but I find Moquin-Tandon treats in his 'Tératologie'on villosity of plants, and seems to attribute more to dryness than altitude; but seems to think that it must be admitted that mountain plants are villose, and that this villosity is only. in part explained by De Candolle's remark that the dwarfed condition of mountain plants would condense the hairs, and so give them the appearance of being more hairy. He quotes Senebier, ‘Physiologie Végétale,' as authority-I suppose the first authority, for mountain plants being hairy.
If I could show positively that the endemic species were more hairy in dry districts, then the case of the varieties becoming more hairy in dry ground would be a fact for
Down, June 3rd (1857). MY DEAR HOOKER, -I am going to enjoy myself by having a prose on my own subjects to you, and this is a greater enjoyment to me than you will readily understand, as I for months together do not open my mouth on Natural History. Your letter is of great value to me, and staggers me in regard to my proposition. I dare say the absence of botanical facts may in part be accounted for by the difficulty of measuring slight variations. Indeed, after writing, this occurred to me; for I have Crucianella stylosa coming into flower, and the pistil ought to be very variable in length, and thinking of this I at once felt how could one judge whether it was variable in any high degree. How different, for instance, from the beak of a bird ! But I am not satisfied with this explanation, and am staggered. Yet I think there is something in the law ; I have had so many instances, as the following: I wrote to Wollaston to ask him to run through the Madeira Beetles and tell me whether any one presented anything very anomalous in relation to its allies. He gave me a unique case of an enormous head in a female, and then I found in his book, already stated, that the size of the head was astonishingly variable. Part of the difference with plants may be accounted for by many of my cases being secondary male or female characters, but then I have striking cases with hermaphrodite Cirripedes. The cases seem to me far too numerous for accidental coincidences, of great variability and abnormal development. I presume that you will not object to my putting a note saying that you had reflected over the case, and though one or two cases seemed to support, quite as many or more seemed wholly contradictory. This want of evidence
is the more surprising to me, as generally I find any proposition more easily tested by observations in botanical works, which I have picked up, than in zoological works. I never dreamed that you had kept the subject at all before your mind. Altogether the case is one more of my many horrid puzzles. My observations, though on so infinitely a small scale, on the struggle for existence, begin to make me see a little clearer how the fight goes on.
Out of sixteen kinds of seed sown on my meadow, fifteen have germinated, but now they are perishing at such a rate that I doubt whether more than one will flower. Here we have choking which has taken place likewise on a great scale, with plants not seedlings, in a bit of my lawn allowed to grow up. On the other hand, in a bit of ground, 2 by 3 feet, I have daily marked each seedling weed as it has appeared during March, April and May, and 357 have come up, and of these 277 have already been killed, chiefly by slugs. By the way, at Moor Park, I saw rather a pretty case of the effects of animals on vegetation : there are enormous commons with clumps of old Scotch firs on the hills, and about eight or ten years ago some of these commons were enclosed, and all round the clumps nice young trees are springing up by the million, looking exactly as if planted, so many are of the same age. In other parts of the common, not yet enclosed, I looked for miles and not one young tree could be seen. I then went near (within quarter of a mile of the clumps) and looked closely in the heather, and there I found tens of thousands of young Scotch firs (thirty in one square yard) with their tops nibbled off by the few cattle which occasionally roam over these wretched heaths. One little tree, three inches high, by the rings appeared to be twenty-six years old, with a short stem about as thick as a stick of sealing-wax, What a wondrous problem it is, what a play of forces, determining the kind and proportion of each plant in a square yard of turf! It is to my mind truly wonderful. And yet we are pleased to wonder when some animal or plant becomes extinct.
I am so sorry that you will not be at the Club. I see Mrs.