Ɛpsilon

To Lawson Tait   4 June [1875]1

Abinger Hall | Wotton, Surrey

June 4th

My dear Sir

I have been much interested by your letter.— When I made little slits in the leaves for the sake of ascertaining the direction in which the motor impulse is transmitted, I found that the lobe on the injured side did not move on irritating one of sensitive filaments on that side, but that the opposite lobe did move. So for case like yours.2 You will be better judge than I, but I attributed the result to the injury affecting power of movement in a greater degree than power of transmission of motor impulse.— You will find one or two analogous facts, & under Drosera what seems to me a truly reflex action.— You will see why I doubt about nerves.3

If you make out about the tails of mice, it will be a beautiful little discovery: I enjoy it the more, because some German sneered at Nat. Selection, & instanced the tail of the mouse: I think it was Bronn.—4

A friend has lent us this house for a month, for a change as I am quite done up with correcting Proofs (very nearly finished, & Dionæa quite finished) of my book.—5

So excuse brevity— You will of course publish on Dionæa—6 I hope so.—

yours very sincerely | Ch. Darwin

1
The year is established by the relationship between this letter and the letter from Lawson Tait, 2 June [1875].
2
In his letter of 2 June [1875], Tait described how one side of a heat-damaged leaf-trap of a specimen of Dionaea muscipula (Venus fly trap) curled and closed when a filament on the opposite side was irritated.
3
In Insectivorous plants, pp. 229–61, CD discussed leaf sensitivity and the lines of transmission of the motor impulse in Drosera rotundifolia (common sundew). CD described the process of aggregation of cells in the glands of tentacles as a reflex action, but noted that the process was different in its action from that in sensory nerves of animals (ibid., pp. 242–3).
4
In his translation of Origin into German, Heinrich Georg Bronn had appended a chapter in which he discussed CD’s theory (Bronn trans. 1860, pp. 495–520). Bronn argued that some features, such as the length of the tail in rats, had no value, and hence they could not be subject to natural selection (ibid., pp. 504–5). CD discussed Bronn’s objection in Origin 6th ed., pp. 171–2.
5
CD stayed at Abinger Hall, Dorking, Surrey, the home of Thomas Henry Farrer, from 3 June to 6 July 1875. Insectivorous plants was published on 2 July 1875. (See CD’s ‘Journal’ (Appendix II).)
6
Tait read a paper on insectivorous plants to the Birmingham Natural History Society on 17 June 1875, and discussed his experiments on Drosera in a letter published in Nature, 29 July 1875, pp. 251–2. He later published a paper, ‘Researches on the digestive principles of plants’ (Tait 1879). He did not publish observations on reflex action in Dionaea.

Manuscript Alterations and Comments

0.1 Surrey] before del ‘Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.’
1.1 little] interl
1.2 ,] after del ‘is transmitted’
1.4 lobe] above del ‘side’
2.3 the mouse] ‘the’ interl
3.1 for a change] interl
3.2 book.—] above del ‘book.—’

Please cite as “DCP-LETT-10009,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10009