The date is established by the relationship to the letter from W. E. Darwin, 21 October [1862], and to the letter to W. E. Darwin, 30 [October 1862], and by reference to dated notes by CD and William, recording the numbers of seeds counted in the pods of Lythrum salicaria (see nn. 2 and 3, below).

CD had asked William to count the seeds from six pods of each of the three forms of Lythrum salicaria, collected from plants growing wild near Southampton (see letter from W. E. Darwin, 21 October [1862], and letter to W. E. Darwin, 30 [October 1862]). On 2 November 1862, William recorded in his Botanical notebook (DAR 117: 50) that he had counted the seeds in one pod of the long-styled form, excluding ‘those evidently void or those shrivelled on the convex side’.

In October 1862, William had sent his father pods of each of the three forms of Lythrum salicaria, collected from plants growing wild near Southampton (see letter from W. E. Darwin, 21 October [1862] and nn. 2 and 3). CD’s tally of the seeds from thirty-one of these pods is in DAR 27.2 (ser. 2): 45, 55–6; some of these notes are dated 8 and 13 October. In addition, his tally of the seeds from twenty-one pods collected from plants grown in his garden and pollinated by insects, is in DAR 27.2 (ser. 2): 53, dated 17 October 1862. CD’s results from the crosses made with this species in 1862 are also recorded in DAR 27.2 (ser. 2).

See letter to J. D. Hooker, 27 [October 1862] and n. 11.