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Darwin Correspondence Project

To Francis Darwin   18 June [1878]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

June 18th

My dear Frank

You will see by enclosed that there is poor chance of getting Ciesiskis: could you borrow it from Sachs & read it, & see whether anything concerns us, & under what circumstances the radicles bent from water?2

I have now done a good many leaves & shall do only 4 or 5 more, for all circumnutate in a plain manner, & closely like cotyledons.— I have also been observing the movements of some cotyledons & it is clear that sleep movement is nothing but exaggerated circumnutation.3

I have got an odd little fact with Oxalis: the cotyledons of O. Valdiviana rise vertically up late in evening, whilst those of O. rosea & floribunda sink vertically down. There is something very odd about the hypocotyl of O. rosea; if tied with a thread to a pin or very thin stick, or if tied to nothing, it makes both cotyledons to sink downwards in a marked manner, but I must experimentise more about this odd transmitted sensitiveness.4

Radicles have been going very badly, neither decidedly negative nor positive; & this is an odious state of things.5

I hope in a fortnight to have done with spontaneous movements, & then must begin on light.—6 This work, with no writing, I find very wholesome, but very tiring.

Bernard7 lately has had many servile admirers & he is as charming as charming can be.—

Your affect Father | C. Darwin

Could you easily go at night into Botanic garden green House or Hot House & look out for sleepers?8


The year is established by the relationship between this letter and the letter to W. T. Thiselton-Dyer, 18 June [1878].
The enclosure has not been found. Francis had been working with CD on various experiments on movement in plants and was now visiting Julius Sachs’s laboratory at Würzburg from 3 June until 8 August 1878 (Emma Darwin’s diary (DAR 242); letter from Emma Darwin to W. E. Darwin, [11 August 1878] (DAR 219.1: 114)). Sachs had referred to Theophil Ciesielski’s article on the circumstances in which radicles grew upwards away from moisture but he had observed different results (Sachs 1872, p. 219, Ciesielski 1871, p. 33; see letter to Francis Darwin, [13–26 May 1878] and n. 3).
CD was observing the movement of leaves and cotyledons (seed-leaves); see letter to W. T. Thiselton-Dyer, 2 June 1878.
See also letter to W. T. Thiselton-Dyer, 18 June [1878]. Oxalis valdiviana is a synonym of O. valdiviensis (Chilean yellow-sorrel); O. floribunda is abundant flowering wood sorrel. These experiments with the hypocotyl (the stem that supports the cotyledons) of O. rosea (pink sorrel) are reported in Movement in plants, pp. 23–5. For CD’s previous work on transmitted sensitiveness in Drosera (sundew) and Dionaea (Venus fly trap), see Insectivorous plants, pp. 364–7.
CD’s experimental notes on the movement of radicles (embryonic roots) are in DAR 209.5.
CD resumed his experiments on heliotropism in early July 1878; see letter to Francis Darwin, 2 July [1878].
Francis Darwin’s son, Bernard Darwin.
Sachs was director of the Würzburg botanic garden, which was attached to his laboratory of plant physiology (Botanische Garten der Universität Würzburg,, accessed 23 May 2017).


Ciesielski, Theophil. 1871. Untersuchungen über die Abwärtskrümmung der Wurzel. Inaugural-Dissertation welche mit Genehmigung philosophischen Facultät der königl. Universität zu Breslau zur Erlangung der Doctorwürde. Breslau: R. Nischkowsky.

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

Movement in plants: The power of movement in plants. By Charles Darwin. Assisted by Francis Darwin. London: John Murray. 1880.


Has been observing the movements of leaves and cotyledons; sleep movements are exaggerated circumnutation. Reports some odd observations on movement in Oxalis species.

Letter details

Letter no.
Charles Robert Darwin
Francis Darwin
Sent from
Source of text
DAR 211: 27
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 11559,” accessed on 6 March 2021,