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Darwin Correspondence Project

To J. D. Hooker   3 November [1873]1

Down, | Beckenham, Kent.

Nov. 3d

My dear Hooker

I never for a moment dreamed of your deferring the publication of your paper, & it would be a pity. But of course I shall be very glad to mention any of the facts which illustrate my work, & this will be of the highest value to me, as others will believe far more readily what you have also seen, than what I have alone, who am no botanist.— I do not suppose I shall begin printing for 3 or 4 months, as my matter is spreading out.2 But the time will largely depend on health.

I think from my own trials that the colour of litmus paper would show you whether the fluid was rendered more acid (1) by mechanical irritation, in comparison to what it was before & (2d) by the addition of a few drops of the infusion of raw meat, but you wd have to observe how far this addition by itself at once affected the litmus paper.— If you knew before hand the appearance of the glands in a virgin pitcher, you wd be able to learn after giving the infusion of raw meat— whether this caused aggregation like that from C. of Ammonia. It ought to do so judging from Drosera, & this wd be an important fact to learn.3

It is precious easy to suggest experiments, & often most difficult, as I know to my cost, to carry them out. But I would in your case cut out a rather large square hole (or fistula) on one side of pitcher, (I did this with Dionæa & it not prevent leaf acting)

Empty fluid & dry with blotting paper opposite side of pitcher, & then after a time I shd. think you would see beads of secretion on the glands.— I enclose some fibrin which must be kept in glycerine, & can easily be washed before being used. I would at the same time stick on a bit (after pressing it a little between blotting paper) on opposite side of Pitcher & see if this does not increase or quicken the secretion & its acid reaction. I shd not be surprised if it made secretion in 10′ or 15′. As a control experiment you could stick on a bit of equally damp cotton or moss on another point.— Possibly fibrin as it decays may become feebly acid, so look out for this.—

It was much better for me to receive leaves of Eucalyptus & Acacia selected by hazard

Let me have Lathyrus nissolia seeds, as soon as you have any

I will settle about Mimosa albida, when I have examined, on my return from London, Aca. farnesiana.4

You understand that any plant of any Family with a terminal or any lateral leaflets greatly reduced in size would be very interesting to me for studying its spontaneous movement; but Leguminoseæ wd. be best—

I have not received from Rollisson the Eucalyptic & Australian Acacias:5 perhaps he has none, & puts the names in his list for ornament. I must try & come to Kew.— What an evil it is to be so easily knocked up; but I am sure that Dr Clarke is doing me good, though I am tired enough this evening6

Yours affect | Ch Darwin.

Very many thanks for the names, including so many specific names!!7 Hurrah.—

P.S. Even little cube of the hardest cartilage from raw joint of sheep is completely softened & partly dissolved in 48o by Drosera: whereas cold water of course effects nothing.— This is a very striking, but not really more remarkable experiment than the same with roast meat or albumen.


This letter was published in Correspondence vol. 21 from a copy at CUL; the original was later found at the Royal Botanic Gardens, Kew. The year is established by the relationship between this letter and the letter from J. D. Hooker, [1 November 1873].
Hooker was trying to repeat experiments on the digestive juices of Nepenthes (the tropical pitcher-plant) that CD had performed on Drosera (sundew) and other plants (see Correspondence vol. 21, letter from J. D. Hooker, [1 November 1873]). CD’s work on Drosera was not published until 1875 in Insectivorous plants; he acknowledged Hooker’s work on the digestive properties of Nepenthes on p. 96.
On CD’s use of carbonate of ammonia with Drosera, see Correspondence vol. 21, letter to J. D. Hooker, 5 January [1873].
See Correspondence vol. 21, letter from J. D. Hooker, [1 November 1873] and nn. 3 and 4. CD wished to observe leaf structure and movement in species of Eucalyptus and Acacia, in Lathyrus nissolia, and in Mimosa albida. He had received a living specimen of Acacia farnesiana.
CD had ordered plants from the nurseryman George Rollisson (see Correspondence vol. 21, letter to J. D. Hooker, 30 October [1873]).
CD had begun to consult Andrew Clark earlier in 1873 (see Correspondence vol. 21, letter to Charles Lyell, 24 September 1873).
For the list of species names, see Correspondence vol. 21, enclosure to letter from J. D. Hooker, [1 November 1873].


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 26 vols to date. Cambridge: Cambridge University Press. 1985–.

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


Discusses experiments and observations on pitchers [of Nepenthes]. Suggests procedures for JDH to follow.

Any plant of any family with a terminal or with any lateral leaflets greatly reduced would be interesting to CD for studying spontaneous movements.

Has not received Eucalyptus or Acacia plants from Rollisson.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
Royal Botanic Garden Kew (JDH/3/6 Insectivorous plants 1873–8 ff. 2–3 and 39a)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9130,” accessed on 14 October 2019,

Also published in The Correspondence of Charles Darwin, vol. 21 and 24 (Supplement)