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Darwin Correspondence Project

To J. S. Burdon Sanderson   31 March [1874]1

Down, | Beckenham, Kent.

March 31st

My dear Dr. Sanderson.

How carefully & excellently you have made the experiments, which I fear must have cost you much trouble. They will be most useful to me, especially those on the acids & I am greatly obliged to you.2 There is one point which you do not mention, & which I ought to know, viz the temperature at which the experiments were tried. Drosera digests at ordinary summer temperatures, & as far as casual observations serve almost equally well during ordinary summer weather & very hot weather. If you tried your experiments at the heat of human body or above that, it is just possible that the fatty acids would run a better race with the Hydrochloric at lower temperatures. Would it not be worth while to try one of the fatty acids & the Hydrochloric at ordinary temperatures?3

Again heartily thanking you | Yours very sincerely | Ch. Darwin

If all the globuline which I sent has not been used or thrown away,4 will you return me a few grains, as I shd like to try a few particles on Drosera aiding the plant with a minute drop of very weak Hydrochloric acid.—

P.S. I do not at present think that I shall try more digestion-experiments with Drosera this summer; not but what I like the work much, & your most kind offer is very tempting, but then I have other matter almost ready for publication & which, if I go on, I shall never have strength to publish.—5


The year is established by the relationship between this letter and the letter from J. S. Burdon Sanderson, 30 March [1874].
CD wanted to determine whether the digestive process of insectivorous plants such as Drosera (sundew) was analogous to that of animals (see Insectivorous plants, p. 85).
See Correspondence vol. 21, letter to J. S. Burdon Sanderson, 19 November [1873]. Globuline, now known as globulin, is a type of serum protein found in animals.
Burdon Sanderson had offered to compare any of CD’s further plant digestion experiments with pepsin digestion (see letter from J. S. Burdon Sanderson, 30 March [1874]). CD refers to Insectivorous plants.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Insectivorous plants. By Charles Darwin. London: John Murray. 1875.


Thanks for the careful experiments, particularly on organic acids.

Please cite as

Darwin Correspondence Project, “Letter no. 9381,” accessed on 26 March 2023,

Also published in The Correspondence of Charles Darwin, vol. 22