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Darwin Correspondence Project

To J. S. Burdon Sanderson   18 October [1873]1

To try whether Mucin (made by Dr. Moore from a large quantity of mucus), Globuline (from lens of eye) Chlorophyll (now in alcohol & to be evaporated) & Hæmaglobin, can be digested.2

Is Chrondrin more nutritious or more digestible than gelatin?. Dr. Moores says it is more nutritious.3 It acts more efficiently on Drosera than does gelatin; but neither of them at all so efficiently as juice of raw meat, or meat, or albumen &c &c. If not generally known, perhaps Dr. Brunton4 wd. know

If I can get Propionic & Butyric acids, would it be troublesome to ascertain whether these with pepsine will digest albumen & meat.5

C. Darwin

Oct 18th.—


The year is established by the relationship between this letter and the letter to J. S. Burdon Sanderson, 19 November [1873].
Samuel William Moore provided mucin, globulin, chlorophyll, and haemoglobin to CD for his experiments on Drosera rotundifolia (common or round-leaved sundew; letter to Edward Frankland, 29 September 1873, and letters from S. W. Moore, 3 October 1873 and 7 October 1873); CD published the results in Insectivorous plants.
Thomas Lauder Brunton.
CD wanted to compare the digestive action of Drosera with that of artificial digestive fluids in order to more closely identify the digestive agents in Drosera.


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


Suggests experiments on artificial digestion.

Please cite as

Darwin Correspondence Project, “Letter no. 9684,” accessed on 4 August 2021,

Also published in The Correspondence of Charles Darwin, vol. 21