To Daniel Oliver   5 October [1860]1

15 Marine Parade | Eastbourne

Oct. 5th

My dear Sir

I thank you for two notes.2 It was a capital thought your sending me the gum itself (so ingeniously bottled or quilled); I tried it on 3 leaves, & it produced no effect; & I tried thicker gum on 5 other leaves with no effect, & I subsequently proved that these leaves were good ones.3 If a leaf is feeble & does not secrete copiously, the gum dries & draws together all the hairs which it has touched; & this, I imagine, must have been cause of the apparent inflection in your case. At last I have come to a puzzler, for I find Carb. of Soda causes inflection;4 but I have sent to London for pure C. of soda, & as that sold by Druggists is not pure. But I strongly suspect I have come across a poser. I am, however, trying my experiments in another fashion, which may throw light on subject.—   I find the glands at end of Hairs are absorbers as well as secreters. The change which takes place in the Hairs after inflection is very curious. The currents & movements in the cells strike me in my ignorance as marvellous.—

You are very kind in your second note to say that I must not apologise for all the trouble which I have caused; but pray thank Mr Croker for enquiring about the Dionæa.—5 Also please give my best thanks to Sir William for his wish to oblige me;6 I shall be intensely curious to examine the leaves; if I cannot get a plant. If the Dionæa commonly catches only small fry, I shd. not be surprised at a fat fly being too much for its digestion; at least I have found bits of raw meat often, indeed I think generally, kill the leaf of the Drosera. I shd like to hear whether Croker is pretty certain of this fact.—

I am very glad to hear that you are experimentising on the leaves in water. I have long thought that naturalists make far too few experiments.—

My dear Sir | Yours very sincerely | C. Darwin

Do you possess a copy of my “Origin of Species”; if you do not, I should much like to have the pleasure of sending you one.—7

1
Dated by the relationship to the letters from Daniel Oliver, 19 September 1860 and 25 September 1860.
2
The notes from Oliver have not been found.
3
See letter from Daniel Oliver, 25 September 1860, and letter to Daniel Oliver, 27 [September 1860]. CD’s notes on his experiments are in DAR 60.1: 110.
4
CD’s first experiments on Drosera had led him to expect to find that only nitrogenous substances would stimulate inflection of the leaf-hairs.
5
Charles William Crocker was foreman of the propagating department at the Royal Botanic Gardens, Kew. See letter to Daniel Oliver, 15 [September 1860].
6
William Jackson Hooker was the director of the Royal Botanic Gardens, Kew. See letter to Daniel Oliver, [29 September 1860].
7
According to a note by Francis Wall Oliver (Daniel Oliver’s son) added to the typed copy he made of this letter, CD subsequently sent Oliver a copy of the first edition of Origin with a ‘letter of dedication’. However, this would appear to be in error: see second letter to Daniel Oliver, 12 [October 1860], and Appendix III. The letter of dedication recalled by F. W. Oliver may relate to the copy of Journal of researches that CD sent Oliver later in October.

Please cite as “DCP-LETT-2939,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-2939