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Darwin Correspondence Project

From A. W. Bennett   21 September 1874

6, Park Village East, | Regent’s Park, | N.W.

Sept. 21st. 1874.

Dear Sir

The accompanying nos. of the “Botanische Zeitung” have been sent me, containing papers by Dr. H. Hoffmann on variability in the genera Phaseolus & Papaver, which I thought might interest you if you have not already seen them.1 Dr Hoffmann appears to be the author of a work “Untersuchungen zur Bestimmung des Werthes von Species u. Varietäten” (1869) with which I am not acquainted.2

I have been making during the past summer a few fresh observations on Drosera & Pinguicula; but do not know that I have detected anything fresh of much importance. What I did observe I have described to Dr. Hooker, who is, I believe, going to see you soon; & he will explain them to you if he thinks them of any value.3 The most interesting observation to myself is the detection of cells of a peculiar form


beneath the epidermis in the leaves of both these plants & in the glands of Drosera, which I have been able to discover in no other plant except Callitriche: Dr Hooker tells me there are structures of the same kind in Darlingtonia; but whether they have anything to do with the process of digestion I am quite unable to say.4 They appear to be full of a yellowish protoplasm.

Yrs very truly | Alfred W. Bennett

C. Darwin Esq.

A. W. Bennett


a, peculiar bodies in leaf & filament of gland of Drosera; (they are dispersed over the whole leaf. & not confined to the margin).


b similar bodies in leaf of Pinguicula.


Section of leaf of Drosera before unfolding, showing both the surface of the leaf & the filaments of the glands to be covered with papillæ. (These appear to disappear on maturity from the gland-filaments, but not from the surface of the leaf).


Bennett evidently sent copies of Botanische Zeitung for 27 April, 1 May, and 8 May 1874, which contained articles by Hermann Hoffmann on Papaver rhoeas (corn poppy) and on varieties and crosses of garden beans (Hoffmann 1874a and 1874b).
CD’s annotated copy of Hoffmann’s work Untersuchungen zur Bestimmung des Werthes von Species und Varietät. Ein Beitrag zur Kritik der Darwin’schen Hypothese (Researches on the determination of the value of species and variety. A contribution to the critique of the Darwinian hypothesis; Hoffmann 1869) is in the Darwin Pamphlet Collection–CUL.
Joseph Dalton Hooker’s next visit to Down was planned for 26 September 1874 (see letter from J. D. Hooker, 23 September 1874). CD was studying the carnivorous genera Drosera (sundew) and Pinguicula (butterwort) for his work on Insectivorous plants.
Callitriche is the genus of water starworts; Darlingtonia is the monospecific genus of California pitcher-plants. Bennett later described the cells as absorptive glands, noting that they were only present in insectivorous plants, with the exception of Callitriche verna (now C. palustris, vernal water starwort; Bennett 1875, p. 5).


Bennett, Alfred William. 1875. The absorptive glands of carnivorous plants. [Read 1 December 1875.] Monthly Microscopical Journal 15 (1876): 1–5.

Hoffmann, Hermann. 1869. Untersuchungen zur Bestimmung des Werthes von Species und Varietät. Ein Beitrag zur Kritik der Darwin’schen Hypothese. Giessen: J. Ricker’sche Buchhandlung.

Insectivorous plants. By Charles Darwin. London: John Murray. 1875.


Sends papers and references.

Reports his microscopic observations on Drosera and other plants.

Letter details

Letter no.
Alfred William Bennett
Charles Robert Darwin
Sent from
London, Park Village East, 6
Source of text
DAR 160: 142
Physical description
ALS 2pp sketch

Please cite as

Darwin Correspondence Project, “Letter no. 9648,” accessed on 5 July 2022,

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