To J. S. Burdon Sanderson   15 November [1873]1

Down, | Beckenham, Kent.

My dear Dr Sanderson

I have just seen Prof Frankland, and he says that he will send to you in about a week’s time some proprionic and butyric acid, as well as some valeric acid, so as to complete the series; for he thinks that it might have been valeric acid instead of butyric mixed with acetic, which was in drosera;2 and if you will try these acids for artificial digestion I shall be very much obliged. On my return home I will send the globulin and hæmaglobin

Yours very sincerely | Ch. Darwin

Nov 15th. | 2 Bryanston St | Portman Square | (Until early Tuesday morning)3

LS(A)

1
The year is established by the address. CD stayed in Bryanston Street, London, his daughter Henrietta Emma Litchfield’s house, on 15 November only in 1873.
2
These acids are naturally occurring carboxylic acids. CD mistakenly wrote ‘valeric’ instead of ‘valerianic’ acid. Burdon Sanderson’s experiments with these acids are described in Insectivorous plants, pp. 89–91.
3
CD returned to Down on 18 November 1873 (‘Journal’ (Appendix II)).

Manuscript Alterations and Comments

1.2 time] added in CD’s hand
1.4 with] interl in CD’s hand
3.1 (Until … morning)] in CD’s hand
3.1 early] interl

Please cite as “DCP-LETT-9143,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9143