CD had been working on Mimosa since at least August 1873 (see letter to Francis Darwin, 15 August [1873] and n. 10). CD described the movements of M. marginata in Movement in plants, p. 381. In Edwards’s Botanical Register (1838): (Miscellaneous notices) 82, John Lindley described M. marginata, adding that it was sold in nurseries under the names M. mexicana, scandens, and prostrata. He did not describe its movement or say that it was a native of Brazil. Mimosa marginata is now known as M. schleidenii; prostrata was the name given to it by Matthias Jacob Schleiden and Theodor Vogel (International legume database & information service, www.ildis.org (accessed 27 March 2012)).

CD was using chemicals in his experiments on insectivorous plants. No reply to this letter has been found, but CD had long ordered supplies from his chemist in Bromley, William Walmisley Baxter, and lately had been given material, including distilled water, by Edward Frankland and Samuel William Moore (see, for example, letter to W. W. Baxter, 4 September 1873, letter from Edward Frankland, 27 September 1873, and letter from S. W. Moore, 3 October 1873).