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Darwin Correspondence Project

To W. T. Thiselton-Dyer   24 [June 1874]1

Down, | Beckenham, Kent.


My dear Mr Dyer

I fear that you will think me a great bore, but I cannot resist telling you that I have just found out that the leaves of Pinguicola possess a beautifully adapted power of movement. Last night I put on row of little flies near one edge of 2 youngish leaves; & after 14 hours their edges are beautifully folded over so as to clasp the flies, thus bringing the glands into contact with the upper surfaces of the flies, & are now secreting copiously above & below the flies & no doubt absorbing.2 The acid secretion has run down the channelled edge & has collected in the spoon-shaped extremity, where no doubt the glands are absorbing the delicious soup. The leaf on one side looks just like the helix of the human ear, if you were to stuff flies within the fold.

Yours most sincerely | Ch. Darwin

May not the little glandular channelled or folded leaves be those of some Saxifrage?? blown on to the leaves of Pinguicula from the surrounding mountains.3

of 26 leaves from N. Wales each had on average 2.76 insects captured & digested. I have not yet added up the leaves.—4


The date is established by the reference to CD’s experiment with Pinguicula (butterwort; see n. 2 below), and by the relationship between this letter and the letter to W. T. Thiselton-Dyer, 23 June 1874.
According to his notes, CD carried out this experiment on 23 June 1874 (DAR 59.1: 89). See also Insectivorous plants, p. 371.
See letter to W. T. Thiselton-Dyer, 23 June 1874 and n. 5. Thiselton-Dyer identified the leaf in an annotation to this letter as belonging to Erica tetralix (cross-leaved heath).
See letter to W. T. Thiselton-Dyer, 23 June 1874 and n. 3. Francis Darwin’s notes and calculations, with CD’s annotations, on the plant and animal material stuck to the leaves of the Pinguicula specimens received from Amy Ruck on 23 June 1874 are in DAR 59.1: 60–2.


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


Describes how Pinguicula captures insects.

Please cite as

Darwin Correspondence Project, “Letter no. 9562,” accessed on 21 February 2020,

Also published in The Correspondence of Charles Darwin, vol. 22