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Darwin Correspondence Project

To J. S. Burdon Sanderson   13 September [1873]1

Down, | Beckenham, Kent.

Sept. 13th

My dear Dr. Sanderson

How very kind it was of you to telegraph to me. I am quite delighted that you have got a decided result.2 Is it not a very remarkable fact? It seems so to me in my ignorance.— I wish I could remember more distinctly what I formerly read of Du Bois Raymond’s results—3 My poor memory never serves me for more than a vague guide.

I really think you ought to try Drosera.4

In a weak sol. of Phosphate of Ammonia5 (viz 1 gr. to 20 oz of water) it will contract in about 5 minutes & even more quickly in pure warm water; but then water, I suppose, wd prevent your trial.— I forget, but I think it contracts pretty quickly (i.e. in a hour or two) with a large drop of a rather stronger sol. of the Phosphate, or with an atom of raw meat on the disc of the leaf—

Very many thanks for your note just received.6 Do not hunt up for your copy of your paper: for the R. Socy. honoured me some years ago by making me a member, & I find that I have the volume, (beginning about Atropia) & which no doubt I formerly read.—7

Yours most sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter to J. S. Burdon Sanderson, 9 September [1873].
Burdon Sanderson’s telegraph has not been found, but he recorded in his diary for 12 September 1873, ‘Work at Electrical phenomena of Dionaea—Telegraphed Results to Darwin’ (quoted in Frank 1988, p. 281 n. 81). Burdon Sanderson had evidently confirmed the existence of nerve-like tissues in his experiments on Dionaea muscipula (Venus fly trap).
In 1850, Emil Du Bois-Reymond had invented an induction coil and the nerve galvanometer, which he used to generate and measure electrical impulses in animal nerve and muscle tissue (see Du Bois-Reymond 1848–84).
Drosera (sundew) was the genus of carnivorous plants with which CD had done most of his experimental work.
Phosphate of ammonia (ammonium phosphate) is an acid salt of ammonia.
Burdon Sanderson’s note has not been found.
CD may refer to the Royal Society of London; he had been a fellow since 1839. The paper has not been identified.


Du Bois-Reymond, Emil Heinrich. 1848–84. Untersuchungen über thierische Elektricität. 2 vols. in 3. Berlin: G. Reimer.

Frank, Robert G., Jr. 1988. The telltale heart: physiological instruments, graphic methods, and clinical hopes, 1854–1914. In The investigative enterprise: experimental physiology in nineteenth-century medicine, edited by William Coleman and Frederic L. Holmes. Berkeley, Calif., and London: University of California Press.


Thanks JSBS for telegraphing his results, which seem very remarkable; feels he should now try Drosera.

Please cite as

Darwin Correspondence Project, “Letter no. 9055,” accessed on 21 January 2022,

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