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Darwin Correspondence Project

To J. S. Burdon Sanderson   21 June [1874]1

Down, | Beckenham, Kent.

June 21st

My dear Dr. Sanderson

I have received & am heartily obliged for the acids, the fibrin & 2 spec. of fibro-cartilage.— You do not know how valuable the fibrin has proved; both Drosera & Pinguicola have quickly dissolved every atom; so that I shd. have fallen into a grievous error & said that neither could wholly dissolve fibrin: no doubt what I saw left undissolved was impurity in the wretched fibrin which I before employed.2 Thus one great & horrid anomaly is removed. But there remains another, (if I understand rightly), viz that artificial digestive fluid dissolves the fibrous basis of decalcified bone.3 If this is so I must try Drosera again, as it is just possible that D. would not attack the tissue until it had removed every atom of the Phosphate & all free animal matter. The second anomaly is about gluten: I prepared it myself by washing it in water till I got very viscid pale brown substance; but there may have been some starch left, & how I am to ascertain this I know not.—4

I have just read with very great interest your 2d article on Dionæa: it is most wonderful that there shd. be that identity between muscle & a leaf.—5 I fear that you misunderstood me on the point: the aggregation of the protoplasm does not occur until sometime after the movement has occurred.6 But to look closer to this point has been a subject on my list for closer observation for some little time. Again aggregation occurs with no movement ensues, as when too strong a dose (viz 2 or 3 gr. of carbonate of A. to 1 oz) is given.—7

I do not think I expressed in my last note how very much I was pleased by your very honourable & encouraging notice of my work.8

Yours most sincerely | Ch. Darwin

P. S. Your man has made an odd mistake & has sent me vertebral bones with no cartilege; but Frank has now come home, & knows fibro-cartilege, & will get me some from a joint or from the Butchers’.—9


The year is established by the relationship between this letter and the letter from J. S. Burdon Sanderson, 19 June 1874. This letter was published without the postscript in Correspondence vol. 22.
See Correspondence vol. 22, letter from J. S. Burdon Sanderson, 19 June 1874. CD described his experiments on Drosera (sundew) both with his first sample and with the fibrin sent by Burdon Sanderson in Insectivorous plants, pp. 100–2. CD described similar experiments on Pinguicula (butterwort) in ibid., p. 383.
Burdon Sanderson had reported that artificial gastric juice dissolved bone entirely in his letter of 26 May [1874] (Correspondence vol. 22).
Burdon Sanderson reported the results of his experiments on the relative digestibility of gluten and fibrin in his letter of 12 May [1874] (Correspondence vol. 22); he later noted that gluten was completely dissolved in tests with three different acids (see ibid., letter from J. S. Burdon Sanderson, 26 May [1874]).
The second part of Burdon Sanderson 1874 was published in Nature, 18 June 1874 (see Correspondence vol. 22, letter to J. S. Burdon Sanderson, 12 June 1874 and n. 1). Burdon Sanderson concluded that the response of Dionaea to electrical stimulation was similar to that of animal muscle except that the period of latent stimulation was longer (Burdon Sanderson 1874, p. 128).
See Burdon Sanderson 1874, pp. 127–8.
In Insectivorous plants, pp. 43–4, CD noted that carbonate of ammonia was the substance that induced the quickest and most powerful aggregation of cells in glands of Drosera.
See Burdon Sanderson 1874, pp. 106 and 107.
CD had asked for ‘a bit of fibro-cartilege from any animal’ to feed to Drosera (see Correspondence vol. 22, letter to J. S. Burdon Sanderson, 14 May 1874, and Insectivorous plants, pp. 104–5). Francis Darwin returned to Down on 20 June 1874 (Emma Darwin’s diary (DAR 242)).


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.


Thanks for fibrin. Drosera and Pinguicula dissolve it thoroughly.

Please cite as

Darwin Correspondence Project, “Letter no. 9504,” accessed on 16 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 24 (Supplement) and 22