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Darwin Correspondence Project

To F. J. Cohn   12 October 1874

Down, | Beckenham, Kent.

Oct 12th 1874

My dear Sir

I thank you for your very kind letter, & all the trouble which you have taken in making such excellent sketches of Aldrovanda.1 It is very good of you to offer to send me specimens next summer; but Dr Hooker came here two days after I had written to you, & by a strange coincidence he had received the day before plants from Germany, & has sent me some.2 I immediately cut open a leaf, & saw everything exactly as you have described it.3 The plants have very few good leaves, & these will not open, which I much regret as I should like to try a few experiments. I have placed the terminal buds under different temperatures in hopes of forcing them forward.

I have observed the structure of Dionaea only so far as would aid my observations on the functions of the several parts; & in regard to the mechanism of the movement, I have made only a few superficial observations.4 This is your own subject, & I well remember how interested I was some years ago by your observations on the stamens of certain Composita.5 I hope therefore that you will publish, & it is much too generous on your part to think of delaying, on my account. I am glad that we do not differ about the valve of Utricularia, & that I misunderstood your account.6 I have just found out from Hooker that my chief work has been on a very rare British species viz U. neglecta though I have observed U. vulgaris.7 Many thanks for your essay, but I have had time only just to look at it, as I am to my never-ceasing regret a very poor German scholar. I shall be extremely glad to receive a complete copy of yr work on Aldrovanda &c8

With sincere thanks & respect | I remain dear Sir yours very faithfully | Charles Darwin


See letter from F. J. Cohn, 4 October 1874. The sketches have not been found.
See letter from F. J. Cohn, 4 October 1874. Joseph Dalton Hooker’s daughter Harriet Anne Hooker sent Aldrovanda vesiculosa (the waterwheel plant) to CD; see letter from J. D. Hooker, 29 September 1874. Hooker visited Down on 26 September 1874 (letter from J. D. Hooker, 23 September 1874).
See letter from F. J. Cohn, 4 October 1874, and F. J. Cohn 1875, of which CD had received a copy in advance of its publication.
Compositae (now Asteraceae) are the large and widespread family of asters, daisies, and sunflowers. A heavily annotated copy of Cohn’s article, ‘Ueber contractile Gewebe im Pflanzenreich’ (F. J. Cohn 1860), is in the Darwin Pamphlet Collection–CUL. An English abstract was published in the Annals and Magazine of Natural History 11 (1863): 188–202. CD referred to both the original article and the abstract in Insectivorous plants, pp. 256 and 364.
For J. D. Hooker’s identifications, see the letter from J. D. Hooker, 29 September 1874.
CD’s annotated copy of F. J. Cohn 1875 is in DAR 58.2: 35–43.


CD responds [to 9667] with description of his own effort to study Aldrovanda and his observations on the structure of Dionaea.

His admiration for FJC’s earlier studies of the Venus’s fly-trap.

He urges FJC to proceed promptly with publication of his memoir on Aldrovanda [Beiträge zur Biologie der Pflanzen 1, Heft 3 (1875): 71–92].

Letter details

Letter no.
Charles Robert Darwin
Ferdinand Julius Cohn
Sent from
Source of text
DAR 185: 107
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9677A,” accessed on 22 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 22