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Letter 2101

Darwin, C. R. to Hooker, J. D.

3 June [1857]
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    Summary Add

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    "Law" [see 2092] correlating variability and abnormal development not confirmed by JDH for plants.

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    CD studies struggle for existence in his weed garden.

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    Scotch fir observed at Moor Park.

Transcription

Down Bromley Kent

June 3d

My dear Hooker

I am going to enjoy myself by having a prose on my own subjects to you, & this is a greater enjoyment to me than you will readily understand; as I for months together do not open my mouth on Nat. History.— Your letter is of great value to me & staggers me in regard to my proposition. I daresay the absence of Bot. 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 & the pistil ought to be very variable in length, & thinking of this I at once felt how could one judge whether it was variable in any high degree. How different, for instance, from Beak of Bird!— But I am not satisfied with this explanation, & am staggered. Yet I think there is something in law; I have had so many instances as following: I wrote to Wollaston to ask him to run through Madeira Beetles & tell me whether any one presented anything very anomalous in relation to its allies: he gave me a unique case of enormous head in female & then I found in his Book already stated that the size of head was astonishingly variable.— Part of 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 & abnormal development. I presume you will not object to my putting a note saying that you had reflected over case & 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 Bot. 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 16 kinds of seed sown on my meadow, 15 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 great scale with plant not seedlings in a bit of my lawn allowed to grow up. On other hand in a bit of ground 23 feet, I have daily marked each seedling weed as it has appeared during March, April & May, and 357 have come up, & of these 277 have already been killed chiefly by slugs.— By the way at Moor Park, I saw rather pretty case of effect of animals on vegetation: there are enormous commons with clumps of old Scotch firs on hills, & about 8–10 years ago some of these commons were enclosed & all round the clumps nice young trees are springing up by the millions, looking exactly as if planted so many are of same age. In other part of common, not yet enclosed, I looked for miles & not one young tree cd be seen; I then went near (within 14 of mile of the clumps & looked closely in the heather, & there I found tens of thousands of young scotch-firs (30 in one square yard) with their tops nibbled off by the few cattle which occasionally roam over these wretched Heaths. One little tree 3 inches high, by the rings appeared to be 26 years old with a short stem about as thick as stick of sealing wax.— What a wondrous problem it is,—what a play of forces, determining the kinds & proportions 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 Club. I see Mrs Hooker is going to Yarmouth; I trust that the health of your children is not motive.—

Good Bye | My dear Hooker | Ever yours | Ch. Darwin

P.S. | You must not forget sometime to let me have the Himalayan thistle case in short abstract.

I believe you are afraid to send me a ripe Edwardsia pod for fear I shd float it from N. Zealand to Chile!!!

    Footnotes Add

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    f1 2101.f1
    The year is given by CD's reference to experiments carried out in 1857 (see nn. 6 and 7, below) and by dated observations made while he was at Moor Park (see n. 8, below).
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    f2 2101.f2
    See letter to J. D. Hooker, 16 [May 1857]. In the discussion of this subject in Natural selection, p. 308, CD wrote: I applied to Dr. Hooker on this subject, who after careful consideration, informs me that though some facts seem to countenance the rule, yet quite as many or more are opposed to it. In plants one large class of cases, namely secondary sexual characters are not present. Moreover, as Dr. Hooker has remarked to me, in all plants there is so much variability, that it becomes very difficult to form a judgment on the degrees of variability: …
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    f3 2101.f3
    See letter from T. V. Wollaston, [early November 1856].
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    f4 2101.f4
    In Natural selection, p. 308, CD wrote: ‘Moreover from Cirripedes being hermaphrodite, the cases are the more valuable, as clearly showing that the law holds good without any relation to sexual distinctions.’
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    f5 2101.f5
    CD had first mentioned this topic to Hooker in 1852 (see Correspondence vol. 5, letter to J. D. Hooker, [April 1852]).
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    f6 2101.f6
    In an entry in his Experimental book, p. 27 (DAR 157a), headed ‘1857. April 8th’, CD recorded ‘16 K. Garden seeds sown on Grass field.—’. Commenting several weeks later on the fate of the young seedlings, CD wrote: ‘I shd think most germinated, & then came battle for life with slugs & insects & other plants’. (DAR 157a, p. 28).
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    f7 2101.f7
    This experiment, labelled ‘Weed Garden’, is recorded in CD's Experimental book, pp. 24, 25 (DAR 157a). An entry of 1 June 1857 tallies the results to June and gives the figures that CD cited to Hooker.
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    f8 2101.f8
    These observations are described in notes dated 3 May 1857 in DAR 46.1: 38–9. They are transcribed as an appendix to Natural selection, pp. 570–1.
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