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Darwin Correspondence Project

To T. L. Brunton   4 March 1874

Down. Beckenham— Kent

Mar. 4. 1874

Dear Sir

I thank you for your long letter which has interested me to an extreme degree. It has been very kind of you to take so much trouble about the Chlorophyl, on which subject I felt much curiosity—1 The parallelism in the digestive power of the secretion of Drosera & of the stomach of the higher animals seems to me extraordinary   All albumenous substances, including the hardest cartilage, which man can digest, so can Drosera—2 But I found that the secretion of the latter wd not touch Chlorophyl Globuline, Mucin, & chemically prepared casein: & from what I have lately heard from Burdon Sanderson, & read in Schiff, so it is with gastric juice—3 I have also been very glad to hear about gelatine & to read your essay in the Med. Record—4

You have proved abundantly that the human face can differ on the two sides— When I first heard of your idea, it did not seem to me probable, but I stupidly forgot the case of a snarl or sneer— I will preserve your letter until there is a new Ed. of my book.5

Your idea about the origin of serpent & fire-worship strikes me as singularly ingenious: & is the only explanation with any probability of which I have ever heard.6 Again I thank you for your very interesting letter— When I next come to London which however will not be very soon, I will have the pleasure of calling on you in the belief that you will allow me—

Believe me | My dear Sir | yours truly obliged | Ch. Darwin

If you should ever meet with anything on the nutritive power of Chondrin I shd be very glad to hear of it.7 I lately read with some interest in Proc. R. Soc. about snake poisons & was surprised & even amused at the extraordinary simple explanation of venomous snakes not killing each other which always seemed to me a most mysterious circumstance—8


CD described the ability of Drosera (sundew) and artificial gastric juice to dissolve cartilage in Insectivorous plants, pp. 103–5.
CD discussed these substances, which were unaffected by the secretion of Drosera leaves, in Insectivorous plants, pp. 115, 131, 134, and quoted Moritz Schiff’s observation that gastric juice had no effect on chemically prepared casein (ibid., p. 116; Schiff 1867, 2: 153). CD had sent particles of globulin to John Scott Burdon Sanderson and asked him to test the effects of artificial gastric juice on them (see Correspondence vol. 21, letter J. S. Burdon Sanderson, 19 November [1873]); the results of Burdon Sanderson’s experiments using fresh globulin prepared by himself were given in Insectivorous plants, pp. 120–1.
Brunton had published ‘Voit on the nutritive value of gelatine’ in Medical Record, 22 January 1873, pp. 36–7. See letter from T. L. Brunton, 28 February 1874 and n. 7.
See letter from T. L. Brunton, 28 February 1874. Brunton had first suggested that expression could differ on the two sides of the face in December 1873 (see Correspondence vol. 21, letter from T. L. Brunton, 2 December 1873). There is no reference to Brunton in Expression 2d ed., but CD evidently cut off this section of the letter from T. L. Brunton, 28 February 1874, to keep in his collection of letters for the second edition (Expression 2d ed., p. iii).
The remaining fragments of this section of the letter from Brunton, 28 February 1874, indicate that he discussed this topic, but there is insufficient readable text to recover his full explanation.
Chondrin is a form of collagen obtained by boiling cartilage in water.
A discussion of the effect of snake-venom on venomous snakes appeared in the second part of a paper by Brunton and Joseph Fayrer in the Proceedings of the Royal Society of London (Brunton and Fayrer 1873–4, pp. 74–5). CD’s lightly annotated copy of this paper, sent to him by Fayrer, is in the Darwin Pamphlet Collection–CUL. Brunton and Fayrer’s experiments showed that venomous snakes were not affected by the venom of their own species or that of others unless they were smaller than the snake that had bitten them; in these cases, however, death may have resulted from bleeding, owing to the size of the fang wounds, rather than from poison (ibid., p. 75 n.).


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

Expression 2d ed.: The expression of the emotions in man and animals. By Charles Darwin. 2d edition. Edited by Francis Darwin. London: John Murray. 1890.

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

Schiff, Moritz. 1867. Leçons sur la physiologie de la digestion, faites au Muséum d’histoire naturelle de Florence. 2 vols. Florence: Hermann Loescher.


On digestive powers of Drosera and those of higher animals.

Comments on expression on two halves of human face.

Responds to TLB’s views of serpent- and fire-worship.

Poison of venomous snakes.

Letter details

Letter no.
Charles Robert Darwin
Thomas Lauder Brunton, 1st baronet
Sent from
Source of text
DAR 143: 159
Physical description
C 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 9334,” accessed on 15 September 2023,

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