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Letter 2965

Darwin, C. R. to Oliver, Daniel

27 [Sept 1860]

    Summary Add

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    Thinks he has worked out simple mechanism of movement in Drosera. Believes he is correct that gum has no effect.

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    Thanks for Trécul paper ["Organisation des glandes pédicellées de la feuille du Drosera rotundifolia", C. R. Hebd. Acad. Sci. 40: 1355–8; Ann. Sci. Nat. (Bot.) 3d ser. 3: 303–11].

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    Chloroform paralyses plants in 30 seconds.

Transcription

15 Marine Parade | Eastbourne

Thursday 27th

My dear Sir

Your note of 25th about the gum has been a great relief to me; for I took a panic, as I know I am very apt to blunder & run away with things. After writing to you I looked through my notes, & found I had been rather more careful, than I thought for I had tried 27 leaves with non-nitrogenised substances, not counting saline solutions & simple water. The more I reflect on the experiments which I have tried the less I think I am mistaken. Thus I fully expected that 1 gr of gelatine to oz. of distilled water, would have affected the leaves, but it produced no effect, whereas a little stronger solution produced a marked effect, & whereas 1 gr to 1 oz of several salts with nitrogen produced strong effect.—   Thick syrup on 5 growing leaves produced no effect, whereas a leaf gathered & put into the same solution suffered in extraordinary degree from exosmose & the the hairs & disc of leaf collapsed; so that the vital power seems to resist exosmose in the living plant. I think I have made out the simple mechanism of movement.—   But why I trouble you with all these details I know not.—

I will give you no more trouble, except that I earnestly hope you will try again the old gum; & if it acts, endeavour to find out certainly its composition. Thank you for the pretty leaf of the Australian Drosera; & for paper with gum; but I have a horrid cold & must stop to another day to try it: a large drop or 12 spoon-full dried & then put on heated knife is proper way to try.—

M. Trecul (I am so much obliged to you for telling me of that paper) disbelieves in any movement & accounts for flies being caught by their crawling under the gumy incurved hairs! But he kept the plants in a green-house or hot-house. Could this have paralysed them? I suppose not: anyhow hot-sunshine seems to make them act better. I imagine he looked out for sudden movement. Vapour of Chloroform for 30 seconds paralyses them completely.—

Thank you much for details of the unnamed Australian species. I will with permission quote your observations. Neither D. spathulata or the other species or D. longifolia seem to move quicker than D. rotundifolia.—

I am very glad to hear that you intend to attack spiny plants. Your note shows that it is a complex problem.—

With many thanks. My dear Sir | Yours sincerely | C. Darwin

I have just received a cargo by Post of living plants of Drosera from Down & I will try more gum & starch myself.—

In the unnamed Australian Drosera the incurvation of the leaf itself was terminal I suppose by your sketch. In D. rotundifolia, sometimes the incurvation is terminal; sometimes lateral; & sometimes termino-lateral, so as to be quite variable: as far as I saw in D. longifolia it was always terminal

    Footnotes Add

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    f1 2965.f1
    Dated by the relationship to the letter from Daniel Oliver, 25 September 1860.
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    f2 2965.f2
    CD cited Tr´ecul 1855 in Insectivorous plants, p. 1 n. Oliver supplied the reference in a letter that is now missing (see letter to Daniel Oliver, 15 [September 1860]). Oliver's note giving the reference is in DAR 60.1: 66.
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    f3 2965.f3
    Oliver's observations were given in the letter from Daniel Oliver, 25 September 1860. They were not cited in Insectivorous plants.
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    f4 2965.f4
    Letter from Daniel Oliver, 25 September 1860.
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    f5 2965.f5
    Notes on CD's experiment, dated `Sunday 30th' and headed `Mr Olivers Gum from Kew, which will have caused contraction.—', are in DAR 60.1: 110.
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