Ɛpsilon

To August Weismann   [17 June 1876 or later]1

Down, Beckenham, Kent

My dear Sir

If you can render sexual selection probable in the case of Daphnia it will be very interesting, especially under the complex circumstances to which you refer.2 Mr. Wallace has recently published an article wholly giving up sexual selection, but on grounds which seem to me extremely weak.3 I am sorry to say that I cannot give you the reference to M. Bert’s observations; but I remember thinking them quite authentic, and knowing what a good authority M. Bert is, did not hesitate to quote them. I suppose that I either saw an extract in a Journal, or received a copy of his paper without any reference as to where it was published, which has often happened.4

I send by this post the first number of Mr. Wilson’s work, pray do not return it at present, and whenever the second number is published I will send it if you care to see it.5

Believe me with much respect | Yours sincerely | Ch. Darwin

Copy

1
The date is established by the reference to Alfred Russel Wallace’s article mentioning sexual selection (see n. 3, below).
2
No letters from Weismann to CD have been found. Weismann’s work on Daphnia (a genus of water fleas) appeared in Beiträge zur Naturgeschichte der Daphnoiden (Contributions to the natural history of daphnoids; Weismann 1879); most parts of the book first appeared as a series of articles (Weismann 1876–80). CD’s annotated copy of parts 2, 3, 4, 6, and 7 of Weismann 1879 is in the Darwin Library–CUL (see Marginalia 1: 854–5). His copy of part 5 of Weismann 1876–80 is in the Darwin Pamphlet Collection–CUL. ‘Complex circumstances’ probably refers to different sequences of parthenogenic and sexual generations in different species and genera in the order Cladocera (water fleas). In his published work, Weismann did not suggest the possibility of sexual selection in any of the subjects of his experiments.
3
Wallace had made some remarks about CD’s theory of sexual selection in the second part of a review published in the Academy on 10 and 17 June 1876 (Wallace 1876b). See letter to A. R. Wallace, 17 June 1876 and n. 18.
4
CD referred to Paul Bert’s work on vision in Daphnia pulex in Descent 2d ed, p. 271: ‘From M. Bert’s observations on Daphnia, when placed in a vessel illuminated by a prism, we have reason to believe that even the lowest crustaceans can distinguish colours.’ Bert’s observations were in Bert 1869.
5
Mr Wilson and his work have not been identified.

Please cite as “DCP-LETT-10335,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10335