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Darwin Correspondence Project

To J. D. Hooker   2 July 1874

Down, | Beckenham, Kent.

July 2nd 74

My dear Hooker

It is real good news that you will come here on Sat the 11th, & we will let you know at what hour a carriage will be at Orpington Station. You are extremely good abt the sick plants, & have relieved my mind from a heavy load; I will defer the whole subjict till nex summer,—that is if I have strength of mind to keep to my! wise resolution.1

I think Frank & I have worked out Pinguicula well; & we long to attack Utricularia: Many thanks for yr aid about this plant; I have myself written to ever so many places for the same.2 I tried several years ago & lately, several plants with sticky glandular hairs, of which some few absorb ammonia, but the greater number not so.3 Could you send me a plant or seeds of Lychnis viscosa & if I find (or you know) that it catches many flies I would certainly examine it; otherwise it would not be worth the time.4 Asa Gray has written much to me lately abt Sarracenia with a dried specimen showing, the line of sweet exudation from the lip down to the ground, by which ground-insects are enticed up & then drowned; it is certainly one of the most splendid dodges in the Vegetable Kingdom. The naturalist who has been investigating this plant believes that it absorbs the decayed matter from flies, but I should think more probably ammonia thus generated.5 It would I think be worth while to protect a pitcher from access of all insects, & to do this cotton-wool wd have to be rolled round the leaf just above the ground as well as putting a net over it; & then to try whether the pure fluid can digest albumin &c. The large quantity of fluid in the pitchers of this plant & of Nepenthes make me suspect that the products of decay may be absorbed & no true act of digestion performed.6 I think you had better call Dyer’s attention to this point, before he attacks Nepenthes again.7

Yrs affectionately


CD and Francis Darwin began studying the digestive powers of Pinguicula (butterwort), a genus of carnivorous plants of the family Lentibulariaceae, in June 1874 (see letter to Asa Gray, 3 June [1874]). CD had also been trying to acquire specimens of Utricularia (bladderwort), another genus of the Lentibulariaceae (see letter to W. D. Fox, 18 June 1874).
In 1866, CD had asked Hooker for a plant of Erica massoni (Masson’s heath) so that he could compare its glandular hairs and secretions with those of Drosera (sundew; see Correspondence vol. 14, letter to J. D. Hooker, 25 September [1866]).
See letter from J. D. Hooker, 1 July 1874 and n. 5. Lychnis viscosa is a synonym of Silene viscaria (sticky catchfly or clammy campion).
Sarracenia variolaris (now Sarracenia minor, the hooded pitcher-plant) was described by Joseph Hinson Mellichamp (Mellichamp 1874; see letters from Asa Gray, 12 May 1874 and n. 4, and 16 June 1874). A summary of his findings was published in Nature, 1 October 1874, p. 442.
In Insectivorous plants, p. 453, CD mentioned Sarracenia as probably incapable of digestion but absorbing the products of the animals it captured.
William Turner Thiselton-Dyer had been assisting Hooker in researching the digestive power of the tropical pitcher-plant, Nepenthes (see letter from J. D. Hooker, 1 July 1874 and n. 3).


Thinks Frank and he have worked out Pinguicula well and they long to attack Utricularia. Tried several plants with sticky glandular hairs; some few absorb ammonia, but the greater number do not. If JDH sends plant or seed of Lychnis CD will examine it to see whether it catches many flies. Asa Gray has written him much about Sarracenia, with a specimen showing the splendid dodge by which ground insects are enticed up and then drowned. Describes how it may be investigated, to see whether it absorbs decayed matter from flies, or ammonia thus generated.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 95: 322–3
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9529,” accessed on 26 May 2019,

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