To J. D. Hooker   14 July [1863]

Down

July 14th

My dear Hooker

I am getting very much amused by my tendrils— it is just the sort of niggling work which suits me & takes up no time & rather rests me whilst writing.1 So will you just think whether you know any plant, which you could give or lend me or I could buy with tendrils remarkable in any way, for development, for odd or peculiar structure or even for odd place in natural arrangement.—2 I have seen or can see Cucurbitaceæ—Passion-flowers—Virginian creeper—Cissus discolor—common Pea & Everlasting pea.—3 It is really curious the diversification of irritability (I do not mean the spontaneous movement, about which I wrote before & correctly as further observation shows);4 for instance I find a slight pinch between thumb & finger at end of tendril of Cucurbitaceæ causes prompt movement, but a pinch excites no movement in Cissus.— The cause is that one side alone, (the concave) is irritable in former; wheres both sides are irritable in Cissus, so if you excite at same time both opposite sides there is no movement; but by touching with a pencil the two branches of tendril in any part whatever you cause movement towards that point; so that I can mould by mere touch the two branches into any shape I like diagram &c &c   The peduncle of tendril is either not sensitive or sensitive only to prolonged though slight pressure &c &c.—5

If you can screw out a little time do come here for a Sunday, I shd. so like it, & I have been better of late & shd. stand some talking well.—

What a splendid number the last of N. Hist. Review.—6 Capital, as they seemed to me, Botanical & Zoological papers.— The embryology of Echinodermata seemed capitally done.7 I suppose I owe to Oliver the capital & clear article on Linum.8

GoodBye, it is awfully hot.— Ever yours affect— | C. Darwin

Endorsement: ‘/63.’

1
CD refers to his experiments on climbing plants, begun in June 1862. See letters to J. D. Hooker, 25 [June 1863] and 1 July [1863].
2
On the back of CD’s letter Hooker listed the following genera and family: ‘Cobæa | Bignonia | Mutisia | Gloriosa | Flagellaria | Lygodium. | Smilax | Leguminosæ’. See also letter from J. D. Hooker, [21 July 1863].
3
CD’s notes on his observations and experiments on climbing plants are in DAR 157.1 and DAR 157.2. These include notes on several members of the Cucurbitaceae, namely: Echinocystis lobata, dated 16 June – 24 May 1864 (DAR 157.2: 29–51 and 53); Hanburya mexicana, dated 12 October [1864] (DAR 157.2: 52); Anguria warscewiczii, dated 29 April 1864, and Zanonia indica, dated 11 April and 20 May [1864] (DAR 157.2: 54). There are also notes on several species of Passiflora (passion flower), dated 27 [July 1863] – 4 August [1864] (DAR 157.2: 69–77); Ampelopsis hederacea (Virginia creeper), dated 1 July – 16 August [1863] (DAR 157.2: 65–7); Cissus discolor, dated 30 June – 18 July [1863] (DAR 157.2: 55–6); Pisum sativum (common pea), dated 30 July – 23 August [1863] (DAR 157.2: 15–20); and Lathyrus grandiflorus (everlasting pea), dated 10–15 November [1863] (DAR 157.2: 22). These species are discussed in ‘Climbing plants’, pp. 65–7, 73–9, 83–7, and 89–91.
5
CD’s notes from these experiments, dated 30 June – 18 July [1863] are in DAR 157.2: 55–6. In his discussion of Cissus discolor in ‘Climbing plants’, CD stated (pp. 83–4): At the beginning of my work, and before examining this plant, I had observed only those tendrils which are sensitive on one side, and these when lightly pressed between the finger and thumb become curved; but on thus pinching many times the tendrils of this Cissus no curvature ensued, and I was at first falsely led to infer that they were not at all sensitive to a touch.
6
CD refers to the July 1863 issue of the Natural History Review, of which Hooker was one of the editors; CD’s unbound copy of this issue of the journal is in the Darwin Library–CUL.
7
Thomson 1863–4.
8
[Oliver] 1863d. Daniel Oliver, who was one of the botanical editors of the Natural History Review, had indicated that he wished to review ‘Two forms in species of Linum’ for the journal (see letter from Daniel Oliver, 27 February 1863; see also letter from J. D. Hooker, [24 March 1863] and n. 11).

Manuscript Alterations and Comments

1.9 between thumb & finger 1.10] interl
1.13 at same time] interl
1.15 mould by mere touch] above del ‘mold’

Please cite as “DCP-LETT-4241,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-4241