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To John Tyndall   20 October [1875]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Oct. 20th

My dear Tyndall

Your tube with the solution dated Oct. 16th. was quite clean at 8o 30’ am on the 19th, but at 4o 30’ p.m was slightly muddy. At 8o am today (20th) it was more muddy & contained many Bacteria (& apparently vibrios) in lively movement. I believe that this is all that you wanted to hear.—.2

I very greatly enjoyed your visit & the talking has done me no harm.—

Yours very sincerely | Ch. Darwin

1
The year is established by the reference to a visit that evidently took place on 16 October; Tyndall visited Down on 16 and 17 October 1875 (Emma Darwin’s diary (DAR 242)).
2
Tyndall probably brought the test tube when he visited Down (see n. 1, above). Tyndall was engaged in a series of experiments on spontaneous generation and had enlisted a number of prominent observers, including CD, Joseph Dalton Hooker, and others, to confirm his results. For more on Tyndall’s work at this time and his dispute with Henry Charlton Bastian about spontaneous generation, see Strick 2000, pp. 162–7.

Manuscript Alterations and Comments

1.1 dated Oct. 16th.] interl

Please cite as “DCP-LETT-10207,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10207