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Darwin Correspondence Project

To J. S. Burdon Sanderson   26 June [1873]1

Down, | Beckenham, Kent.

June 26th

My dear Dr. Sanderson

Your letter is quite invaluable to me & I thank you heartily.2 Nothing can give me more pleasure than to see you here, & to show you anything which you like about Drosera. I will write again & ask you to propose some day to come here to dinner & sleep.3 I have asked poor Sir C. Lyell to come here, who as you know has lately lost his wife, & told him, if he liked to come, that there shd. be no one here.—4 I will write again.

Nitrogenous fluids can hardly act as a ferment, unless indeed they act merely by exciting molecular movements in adjoining molecules; & this view coincides with my conclusion. For atoms of glass, cotton thread (less than 1/50,000 of a grain in Weight) excite movement, & what is more surprising cause the fluid contents of cells forming the tentacles to undergo a visible change; & my description of this has so much surprised Huxley,5 that he is coming down tomorrow night to see the phenomenon.— I have put 1 gr. of the Veratrine to dissolve, but it dissolves very slowly

When I began to try poisons on Drosera, some 12 or 15 years ago, my object was to see whether the poisons affected the plant or if any of its tissues had the same properties as the nervous tissues of animals; but I was disheartened from want of knowledge, & had not time to go on. I shd. never have dreamed of trying glycerine: 4 dropped drops to 1 oz. of water causes the tentacles to bend, i.e. those tentacles the glands of which have absorbed a most minute quantity,. Therefore I expect that tomorrow morning the marginal tentacles will probably be inflected.

With cordial thanks | Yours very sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter from J. S. Burdon Sanderson, 25 June 1873.
Burdon Sanderson and his wife visited Down on 4 July 1873 (Emma Darwin’s diary (DAR 242)).
Charles Lyell’s wife, Mary Elizabeth, died on 24 April 1873. There is no record of Lyell’s visiting Down in June or July 1873 in Emma Darwin’s diary (DAR 242).
Thomas Henry Huxley.


Would welcome JSBS visit to discuss Drosera. Nitrogenous fluids can act as ferments only if they act merely by exciting molecular movement in adjoining molecules.

Glass and cotton excite movement and cause cell contents to change visibly. Huxley coming to see this phenomenon.

Studied effect of poisons 12 or 15 years ago to see whether the action was similar to that on nervous tissue.

Please cite as

Darwin Correspondence Project, “Letter no. 8952,” accessed on 20 January 2022,

Also published in The Correspondence of Charles Darwin, vol. 21