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Darwin Correspondence Project

From J. S. Burdon Sanderson   26 June [1874]1

49 Queen Anne St

June 26

My dear Mr Darwin,

Again I have to apologize for delay. I am on the point of starting on a short tour in Germany and have been much pressed during the last few days in making preparations for my absence.

I am delighted to learn that Pinguicula & Drosera both digest fibrin readily   I do not think it would be correct to infer that the fibrin previously used was impure—but rather that it had undergone change to a certain extent consequent on the way in which it was prepared.2

I think that it would be fairest & best to experiment on gluten already subjected to the action of very dilute Hydrochloric acid (12 per cent)   It would thus be deprived entirely of its starch, which would be dissolved out in the form of Dextrine3   I have ask my assistant Mr. Page4 to send you some already so treated   He will send at the same time some bone treated in the same way. I have no doubt that the reason that the other did not digest completely was that the acid was insufficient to dissolve out the inorganic constituents of the bone

I mentioned in my last that I had put some enamel to digest. It was nearly digested by next morning.5

I am very sorry that I made a misstatement about the “aggregation”6 I said so little about it & expressed myself so indefinitely that I hope that no one would be seriously misled. I felt that I was dealing with a matter about which I had no adequate knowledge.

I hope that it may be possible to do something with Pinguicula about separating the digestive ferment. I should like very much to try after my return.

I am, my dear Mr Darwin | very sincerely yours | J B Sanderson

CD annotations

1.1 Again … absence. 1.3] crossed pencil
2.1 I am … prepared. 2.4] crossed red crayon
3.3 I have … bone 3.7] crossed blue crayon
5.1 I am … knowledge. 5.4] crossed pencil
Top of letter: ‘enamel digested p 2 | on Fibrin not being impure | Gluten & Bone prepapred with 12 pc Hydrochloric A’ pencil


The year is established by the relationship between this letter and the letter to J. S. Burdon Sanderson, 21 June [1874].
Drosera is the sundew; Pinguicula is butterwort. See letter to J. S. Burdon Sanderson, 21 June [1874] and n. 2.
See letter to J. S. Burdon Sanderson, 21 June [1874] and n. 4. Gluten is a protein compound derived from wheat and other grains. Dextrine (now usually spelled dextrin) is a starch that is found together with gluten in the endosperm of the grain.


Is delighted to hear that Pinguicula and Drosera digest fibrin. Suggests diluting gluten in weak hydrochloric acid to remove starch. Enamel was nearly digested [by Drosera] overnight. Would like to try separating the digestive ferment of Pinguicula.

Letter details

Letter no.
John Scott Burdon Sanderson, 1st baronet
Charles Robert Darwin
Sent from
London, Queen Anne St, 49
Source of text
DAR 58.1: 144–5, 153–4
Physical description
ALS 7pp †

Please cite as

Darwin Correspondence Project, “Letter no. 9517,” accessed on 4 June 2023,

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