RECORD: Darwin, C. R. [1872-1873]. ['On the movement of the Leaves of Drosera'] folio 165. CUL-DAR61.106. (John van Wyhe ed., 2002-. The Complete Work of Charles Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed and edited by John van Wyhe 2.2026. RN1

NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volumes CUL-DAR 54-61 contain material for Darwin's book Insectivorous plants (1875).

The volume CUL-DAR61 contains Darwin's draft essay 'On the movement of the leaves of Drosera', written 1872-1873. He intended to publish this with a revised edition of Climbing plants before commencing a larger book draft in April 1874 which became Insectivorous plants. See the introduction to this essay by John van Wyhe.

Draft partly corresponds to Insectivorous plants, p. 196.


[106]

(165

 (The action of organic organic poisons) of one organic in accounting

nature.) on the leaves in accounting or causing  the

or causing the movement of the tentacles.)

Prussic acid.— Hydrogamic acid     I placed minute drops (1/60 of a minnim) of Scheele's mixture, which contains six per cent, or of the pure acid, on the viscid secretion of several glands. In 40' I found the glands & the s the they were coloured bright red & their secretion was from them likewise slightly coloured. After 3° 15' about two-thirds of the tentacles thus treated had become inflected, & they remained so for two days, when they appeared killed dead. I also placed on the discs of five leaves half-minim drops of a weaker mixture, viz containing two per cent of the pure acid. The gland was a before much reddened. The unused shorter tentacles which had, their glands of which was immersed, were inflected after 3° 10'; & next morning after 21° almost every tentacle on all five leaves were unflected, & the leaves tentacles evidently killed much injured. But the other leaves on the same plants appeared quite healthy.

[lower half of page excised]

minim: "The smallest unit of fluid measure, about equivalent to one drop of liquid; the sixtieth part of a fluid drachm." OED.


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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

File last updated 23 February, 2026