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

⁠⟨⁠Bassett, Southampton.⁠⟩⁠

⁠⟨⁠August 21.⁠⟩⁠

⁠⟨⁠My dear Dr. Sanderson⁠⟩⁠

I ⁠⟨⁠45 line⁠⟩⁠ or will ⁠⟨⁠34 line⁠⟩⁠ Germany. ⁠⟨⁠23 line⁠⟩⁠ having a ⁠⟨⁠35 line⁠⟩⁠ Southampton, & return home next Monday.— I shall soon work in some new facts in my Chapt. on digestion by Drosera,2 & I want to ask one question ⁠⟨⁠1 word⁠⟩⁠ you can let me ⁠⟨⁠25 line⁠⟩⁠ ⁠⟨⁠4 or 5 lines⁠⟩⁠ suggested ⁠⟨⁠34 line⁠⟩⁠ne & was ⁠⟨⁠35 line⁠⟩⁠ted. But when not thus treated, it was never completely digested, & the residue does not consist solely of starch. Now in your experiments with artificial digestive fluid, ⁠⟨⁠13 line⁠⟩⁠ ⁠⟨⁠interlineation at top of page⁠⟩⁠ any of the fatty acids did you find the gluten which has not been soaked in hydrochloric acid was digested slowly or imperfectly?3 One other result has surprised me, viz the fibro-cartilage is not digested: my son Frank, made with pepsin & H. acid some artificial digestive fluid, which at the temperature of the room well digested fibrin, but would not digest fibro-cartilage, though it rendered it hyaline & swollen, just as did Drosera.—4

You must read Hooker’s address to Bot. Section at Belfast, & see what a magnificent digester is Nepenthes.—5 I have been almost driven mad by Utricularia which catches no end of entomostraca, but cannot digest, & I believe, though I cannot prove it, that it absorbs the products of putrefaction.6

Yours most sincerely | Ch. Darwin

1
The original letter, which is at the University of British Columbia, is badly damaged. The address, date, and salutation have been restored from an incomplete copy in DAR 147: 415. The year is established by the reference to CD’s visit to Southampton; in 1874, CD returned from visiting his son William Erasmus Darwin in Southampton on Monday 24 August (CD’s ‘Journal’ (Appendix II).
2
CD had been working on his manuscript of Insectivorous plants since April 1874 (CD’s ‘Journal’ (Appendix II)). He presumably refers to chapter 6, ‘The digestive power of the secretion of Drosera’.
3
CD reported Burdon Sanderson’s experiments dissolving gluten in artificial digestive fluid of pepsin with hydrochloric acid in Insectivorous plants, pp. 118–19. Burdon Sanderson had also suggested soaking gluten in weak hydrochloric acid to remove the starch before putting it on Drosera (sundew) leaves.
4
Francis Darwin’s experiments with fibro-cartilage are reported in Insectivorous plants, p. 104. Hyaline: glassy.
5
Joseph Dalton Hooker read an address to the department of botany and zoology at the annual meeting of the British Association for the Advancement of Science, which took place in Belfast from 19 to 26 August 1874 (J. D. Hooker 1874a); his subject was carnivorous plants. In the address, Hooker described his efforts to test the digestive power of Nepenthes (tropical pitcher-plants) by the following the methods that CD had developed for Dionaea muscipula (Venus fly trap) and Drosera.
6
CD discussed the absorption of decayed animals by Utricularia (bladderwort) in Insectivorous plants, pp. 410–24. Entomostraca was the name used to refer to all crustaceans other than Malacostraca (Leftwich 1973).

Manuscript Alterations and Comments

1.3 question] before del ‘or rather two’
1.6 ⁠⟨⁠13 line⁠⟩⁠] before del ‘with hydrochloric or’
1.6 any] after caret
1.10 well] interl
1.10 fibrin,] after del comma
2.4 it,] interl

Please cite as “DCP-LETT-9605,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9605