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Darwin Correspondence Project

To J. D. Hooker   26 September [1862]

Cliff Cottage | Bournemouth

Sept. 26th

My dear Hooker

Do not read this till you have leisure, if that blessed moment ever comes. I shd. be very glad to have your opinion on the subject of this letter. I am led to the opinion that Drosera must have diffused matter, in organic connection, closely analogous to the nervous matter of animals.1 When the gland of one of the papillæ or tentacles, in its natural position (A.), is supplied with nitrogenised fluid & certain other stimulants, or when loaded with an extremely slight weight, or when struck diagram several times with a needle, the pedicel bends, as shown at B, near its base, in under one minute. These varied stimulants are conveyed down the pedicel by some means: it cannot be vibration for drop of fluid put on quite quietly causes the movement: it cannot be absorption of fluid from cell to cell, for I can see rate of absorption, which though quick, is far slower, & in Dionæa the transfusion is instantanous. Analogy from animals would point to transmission through nervous matter. Reflecting on rapid power of absorption in the gland; the extreme sensibility of the whole organ, & the conspicuous movement caused by varied stimulants, I have tried a number of substances, which are not caustic or corrosive, & which I believe do not act on such organic compounds, as sugar gluten cellulose &c, but most of which are known to have a remarkable action on the nervous matter of animals. You will see the result in enclosed paper.2 As the nervous matter of different animals are differently acted on by the same poisons, one would not expect the same action on plants & animals; only if plants have diffused nervous matter, some degree of analogous action. And this is partially the case. Considering these experiments, together with the previously made remarks on the function of the parts, I cannot avoid the conclusion, that Drosera possesses matter at least in some degree analogous in constitution & function to nervous matter.

Now do tell me what you think, as far as you can judge from my abstract. Of course many more experiments would have to be tried; but in former years I tried on whole leaf, instead of on separate glands, a number of innocuous substances such as sugar, gum, starch &c & they produced no effect.— Your opinion will aid me in deciding some future year in going on with this subject.—3

I shd. not have thought it worth attempting, but I had nothing on Earth to do.—4

My dear Hooker | Yours very sincerely | Ch Darwin

We return home on Monday 28th thank Heaven—5


☞ Please return this, as it will aid me hereafter as short abstract6


Small dose of Chloroform, causes rapid, even spasmodic movement; but if very small dose be given & the tentacles do not reach centre, they are paralysed & do not move with meat on gland under from 2 to 4 hours.

Nitric Ether, sometimes causes a few tentacles to move; & thus all are paralysed for some hours.

Sulphuric Ether, caused no movement, & tentacles were paralysed for one or two hours

Alcohol caused no movement; & tentacles were paralysed for about one hour.

Carbonic Acid: plant exposed for one hour; caused no movement, but I think slightly dulled power of movement.

Turpentine, vapour of for 15 caused no movement, & entirely stopped subsequent action of meat.—

All substances used in fluid state
Stramonium } produced no effect; caused no movement, & subsequently meat caused usual rapid movement; I think tea rather dulled power of movement.—
Strong infusion of Tea
Prussic Acid diluted } caused the tentacles to move rapidly.
Strychnine acetate of } caused no movement, & entirely stopped the subsequent action of meat & killed the glands. When a tentacle with an atom of meat had commenced moving the strychnine arrested the movement.
Veratria acetate of } caused no movement; & stopped for many hours any movement from meat; but some tentacles after several hours regained power of movement
Morphia acetate of, & common Opium } caused no movement, & stopped for one or two hours subsequent action of meat, & then the movement was excessively slow
Poison from adders’ fang } caused rapid movement; & produced no subsequent injury; perhaps acted merely like saliva, which from having some nitrogen causes movement
Poison from an Ant } —caused no movement, but stopped subsequent action of meat: concentrated acetic acid acts in same manner.


CD had begun his experiments with the insectivorous plant Drosera rotundifolia in 1860 (see Correspondence vol. 8). He had hoped to continue and complete the experiments in the summer of 1861, but subsequently decided to postpone them (see Correspondence vol. 9, letter to J. D. Hooker, 4 February [1861], and letter to Daniel Oliver, 11 September [1861]). There are notes detailing CD’s experiments with this species between 14 and 26 September 1862, in DAR 54: 29–49. See also letter to Daniel Oliver, [17 September 1862] and n. 12.
See enclosure.
CD did not again work extensively on the subject of insectivorous plants until 1872 (LL 3: 322); his findings were published in 1875 as Insectivorous plants.
CD was on holiday in Bournemouth (see ‘Journal’ (Correspondence vol. 10, Appendix II)); he had begun to study Drosera while ‘idling and resting’ at the Sussex home of his sister-in-law, Sarah Elizabeth Wedgwood, in July 1860 (Autobiography, p. 132; see also Correspondence vol. 8).
This appears to be an error: 28 September 1862 fell on a Sunday. However, CD did not return to Down House until Tuesday 30 September (see ‘Journal’ (Correspondence vol. 10, Appendix II)).
These notes represent an abstract of CD’s experimental notes, dated 14–26 September 1862, which are in DAR 54: 29–49.


Autobiography: The autobiography of Charles Darwin 1809–1882. With original omissions restored. Edited with appendix and notes by Nora Barlow. London: Collins. 1958.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

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

LL: The life and letters of Charles Darwin, including an autobiographical chapter. Edited by Francis Darwin. 3 vols. London: John Murray. 1887–8.


Encloses MS on observations and experiments on Drosera. JDH’s opinion will help him decide whether to pursue subject in some future year.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 60.2: 88, DAR 115: 163
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 3738,” accessed on 12 September 2023,

Also published in The Correspondence of Charles Darwin, vol. 10