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Darwin Correspondence Project

From J. D. Hooker   25 October 1873

Royal Gardens Kew

Oct 25th/73

Dear Darwin

Dyer & I have been busy over Nepenthes & have produced an analogous action to that in the cells of Drosera, in those of the glands of Nepenthes— viz a decided aggregation of protoplasm on application of the Ammon. Carb.—1

We are now trying the egg process. The pieces I put into old pitchers last night were unaffected this morning. Did I understand you that the pieces should be 120 in square? I put in big lumps. We have still a great deal to do before ⁠⟨⁠ar⁠⟩⁠riving at any satisfactory results. The constant presence of insects in all open pitchers is a draw back: & we are going to experiment on virgin pitchers.

I thought I had in my last letter referred you to Voelcker’s analysis of the fluid at Kew in 1849.2

CD annotations

2.2 Did I understand] cross in left margin, ink
2.4 The constant … draw back: 2.5] scored red crayon; ‘Roast meat’ left margin, blue crayon
Top of letter: ‘Suspend one & let one fall to bottom | So with [roast meat] | Cubesblue crayon; ‘Desmodium with 3 leaflets’ blue crayon
First page, left margin: ‘Cutting strike in a month or two’3blue crayon
Bottom of second page, left margin: illeg blue crayon del blue crayon


Hooker refers to William Turner Thiselton-Dyer. CD discussed the effect of carbonate of ammonia on Drosera rotundifolia (the common or round-leaved sundew) in Insectivorous plants, pp. 43–8. He did not mention the effect of carbonate of ammonia (now usually referred to as ammonium carbonate) on Nepenthes (the tropical pitcher-plant).
See letter from J. D. Hooker, 20 October 1873, and letter from W. T. Thiselton-Dyer, [after 20 October 1873?]. Some of the plants that Augustus Voelcker experimented on were from the Royal Botanic Gardens, Kew (Voelcker 1849, p. 238).
CD’s annotations are notes for his letter to Hooker of 26 October [1873].


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

Voelcker, Augustus. 1849. On the chemical composition of the fluid in the ascidia of Nepenthes. [Read 12 July 1849.] Transactions and Proceedings of the Botanical Society of Edinburgh 3 (1850): 233–40. [Also published in Annals and Magazine of Natural History 2d ser. 4: 128–36.]


Describes his experiments on Nepenthes; finds action analogous to that in Drosera.

Letter details

Letter no.
Joseph Dalton Hooker
Charles Robert Darwin
Sent from
Source of text
DAR 103: 175
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9113,” accessed on 6 December 2021,

Also published in The Correspondence of Charles Darwin, vol. 21