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Darwin Correspondence Project

To J. S. Burdon Sanderson   13 October 1874

Down, | Beckenham, Kent.

Oct 13. 1874

My dear Dr. Sanderson

Many thanks for your suggestion, but I doubt whether it is sufficient.1 The tentacles close very slowly over the 5 specified substances, & this might be accounted for by their pure state.2 But the important fact is that they subsequently re-expand so much more quickly than over minute insects, meat albumen etc. It is chiefly this latter fact which makes me conclude that the 5 substances are but little exciting & probably not very nutritious. I made so many experiments with Gelatine that I can hardly doubt that this conclusion is true with this substance.3 Klein speaks (Handbook Phys. p. 445) as if areolar (or connective) tissue & the fibrous basis of bone, were of a gelatinous nature, & this made me suppose that perhaps fibrin & fibro-cartilage were likewise allied to gelatine; & as gelatine is so little nutritious to animals, I imagined that the little action of these 5 substances on drosera might be thus explained.4 My best plan would be, I think, merely to call attention to the small power of the 5 substances on drosera, & to say (if you admit the truth of my inference from Klein) that at least areolar tissue & the fibrous basis of bone were allied to gelatine, & that gelatine was very little nutritious to animals—

I fear from what you say that I may not add that fibrin are likewise allied to gelatine: do you know what is the nature of fibro-cartilage?5 If you have anything further to remark I shd be grateful for a note—

With many thanks, | yours very sincerely | Ch. Darwin


CD refers to fibrin, areolar tissue, the fibrous basis of bone, gelatine, and fibrocartilage (see letter to J. S. Burdon Sanderson, 9 October 1874, and letter from J. S. Burdon Sanderson, 12 October 1874).
CD carried out a number of experiments on the digestion of gelatine by Drosera (sundew) in 1873 (see Correspondence vol. 21, letter to Edward Frankland, 12 July 1873, and letter to J. S. Burdon Sanderson, 25 July 1873), and he described them in Insectivorous plants, pp. 110–12.
In Klein et al. 1873, 1: 445, Thomas Lauder Brunton described the preparation of a substance that he referred to as ‘Ordinary connective tissue.—Tendons.—Gelatinous substance, or collagen’ and as the organic basis of bones and teeth.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

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


Discusses the powers of digestion of Drosera and why certain substances produce less excitement in the plant than others.

Please cite as

Darwin Correspondence Project, “Letter no. 9678,” accessed on 4 August 2021,

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