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Letter 4184

Darwin, C. R. to Crüger, Hermann

25 May [1863]

    Summary Add

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    Thanks for news about fertilisation of Melastomataceae.

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    Discusses fertilisation of orchids.

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    Mentions observations by John Scott.

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    Asks about "bud-variations".

Transcription

Down Bromley | Kent. S.E.

May 25.

Dear Sir

Various circumstances have delayed my thanks for your very interesting letter of Ap 23d.—. I thank you sincerely about the Melastomas: it seems that my suspicion was quite unfounded yet it is just possible that bees may visit the flowers for pollen & suction.— I have wasted a fearful amount of time over this order. There is something very odd about the difference in the two sets of stamens   I first most strongly suspected that the plants on which I experimented were dimorphic; nor should I yet be surprised if this proved to be the case. I shall be very curious to know about the Catasetums & what attracts insects. What a singular fact that of the orchids which did open their flowers setting seeds! A good observer Mr. Scott believes that when the flower is closed the pollen tubes come out of the anther & travel to the stigma. You say you are going to try to make orchis seed germinate: Dr. Hooker tells me that they cannot succeed in Calcutta; but that self-sown foreign plants appears on the surrounding trees!

I am very glad that you have not my Journal and I wrote a week ago to my publisher to send you a copy.— I sent sometime ago a newspaper to you in which I alluded to some of your information. I have also sent a copy of a little paper on the dimorphism of Linum: This is a subject on which I am experimenting with great interest. Have you any analogous cases in the West Indies? You must kindly permit me to ask you questions: have you seen cases of what gardeners call ``sports'' but what I shall call ``bud variation'' (i.e. variation by buds & not by seed) in plants from warmer temperate regions cultivated in the West Indies. I am collecting all cases. Sir R Schomburgk says that temperate plants as Dahlia, Roses &c cultivated in St Domingo are very liable to change in character & give off single shoots different from the mother plant.

with cordial thanks for all your interesting information & great kindness | Dear Sir | Yours sincerely | Ch Darwin

    Footnotes Add

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    f1 4184.f1
    The year is established by the relationship between this letter and the letter from Hermann Cr¨uger, 23 April 1863.
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    f2 4184.f2
    Letter from Hermann Cr¨uger, 23 April 1863.
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    f3 4184.f3
    In his letter to Cr¨uger of 25 January [1863], CD asked about the insects that visited the flowers of Melastomataceae. CD hypothesised that small flies or wasps were attracted by the fluid-filled horns of the anthers, which they penetrated with their probosces. Cr¨uger assured him that the two species of bees seen visiting the flowers of Heteronoma diversifolium came only for pollen; however, he agreed to make further observations of other species of Melastomataceae (see letter from Hermann Cr¨uger, 23 April 1863).
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    f4 4184.f4
    CD refers to the order Melastomaceae (Lindley 1853, p. 731), which corresponds approximately to the modern family Melastomataceae. CD had been working on the Melastomataceae since October 1861, suspecting that the family might exhibit a novel form of dimorphism (see letter to Hugh Falconer, 5 [and 6] January [1863] and n. 22). CD's experimental notes on Melastomataceae are in DAR 205.8.
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    f5 4184.f5
    In his letter to CD of 23 April 1863, Cr¨uger wrote that he was going to investigate a secretion in the flower of the orchid Catasetum tridentatum that appeared to attract bees.
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    f6 4184.f6
    In his letter to CD of 23 April 1863, Cr¨uger wrote of an Epidendrum species with flowers that usually did not open, though his specimen had `fully open' flowers. Cr¨uger reported: `These have not set fruit, while commonly I do not remember to have noticed a flower which was not followed by fruit.'
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    f7 4184.f7
    No letter from John Scott recording these observations has been found; however, see letter to Journal of Horticulture and Cottage Gardener, [17--24 March 1863] and n. 9, and letter from John Scott, [1--11] April [1863].
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    f8 4184.f8
    Joseph Dalton Hooker gave CD this information when he visited Down House on 22 March 1863 (see letter to John Scott, 24 March [1863] and n. 10).
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    f9 4184.f9
    See letter from Hermann Cr¨uger, 23 April 1863; the reference is to Journal of researches (1860). The letter to John Murray, CD's publisher, has not been found.
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    f10 4184.f10
    CD included some information on orchid pollination reported by Cr¨uger (see letter from Hermann Cr¨uger, 23 February 1863 and n. 5) in the letter to the Journal of Horticulture and Cottage Gardener, [17--24 March 1863].
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    f11 4184.f11
    `Two forms in species of Linum'; Cr¨uger's name appears on CD's presentation list for this paper (see Correspondence vol. 11, Appendix IV).
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    f12 4184.f12
    CD was seeking information on the question of whether plants introduced from different climates were particularly apt to produce bud-variations (see Correspondence vol. 10, letter to G. H. K. Thwaites, 29 December [1862]).
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    f13 4184.f13
    Schomburgk 1857, p. 132.
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