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Letter 2886

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

31 [Aug 1860]
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    Summary Add

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    Observations on Drosera: plants can distinguish minute quantities of nitrogenous substances.

Transcription

Down Bromley Kent

31st

My dear Hooker

I know you are frightfully busy; but summer is passing, & I am very curious on point in enclosed paper, would you get your scientific gardener or some one to make the small enclosed observation. It is merely the rate of closing of leaves of Australian Drosera; if they do close.— I am still working at an imported plantation of Drosera; & really one point turns out very curious. The leaves are first rate chemists & can distinguish even an incredibly small quantity of any nitrogenised substance from non=nitrogenised substances. I won't write more, as I know how busy you are.— I hope you are all well.—

C. D.

Etty progress steadily, but very very slowly.— *P [DIAG HERE] *Q

Do not answer this till you have leisure.—

    Footnotes Add

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    f1 2886.f1
    Dated by the relationship to the letter to J. D. Hooker, 2 September [1860].
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    f2 2886.f2
    Daniel Oliver was Hooker's assistant in the herbarium at the Royal Botanic Gardens, Kew. See also letters to J. D. Hooker, 2 September [1860], and to Daniel Oliver, 11 September [1860].
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    f3 2886.f3
    During his research on Drosera rotundifolia carried out in Hartfield in July 1860, CD ascertained that the sticky tentacles borne on the upper surface of the leaf bend over to trap insects. He found that the rate of inflection for the common sundew varied between one and five hours. At this early stage in his study, CD probably did not know whether the Australian sundew (D. spathulata), with long narrow leaves, also caught insects. Later Oliver sent CD a living specimen for his observation (letter to Daniel Oliver, [22--3 September 1860]; see also Insectivorous plants, pp. 280--1). CD found that it took 18 hours for the tentacles of the Australian sundew to curve over a trapped fly (ibid., p. 280).
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    f4 2886.f4
    CD evidently brought several living specimens of D. rotundifolia back with him from Hartfield.
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    f5 2886.f5
    See also letter to J. D. Hooker, 6 September [1860].
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