The year is established by the relationship between this letter and the letter to John Scott, 7 November [1863] (see n. 4, below).

The letter from Scott has not been found.

The letter mentioning the specimen has not been found, but Scott may have again referred to a ripe capsule of Linum monogynum (see letter from John Scott, 21 September [1863]). He eventually sent seeds of this species to CD in January 1864 (see Correspondence vol. 12, letter from John Scott, [13 January 1864]).

After reading the manuscript of Scott’s Primula paper (Scott 1864a), CD asked him to conjecture in the summary what he thought the ancestral form of the genus was (see letter to John Scott, 7 November [1863]). Scott’s reply has not been found; however, in the last two sentences of Scott 1864a (p. 126), Scott referred to his experiments with a non-dimorphic form of the cowslip, P. veris (ibid., pp. 105–8), that he believed had gradually derived from the more common dimorphic forms. He took this as evidence that the original progenitor had been a non-dimorphic form that had also gradually given rise to ‘dimorphically characterized race’. The non-dimorphic form thus presented a case of reversion. CD noted Scott’s conclusion in ‘Illegitimate offspring of dimorphic and trimorphic plants’, p. 435, where he also referred to his own discussion of reversion in Variation (2: 28–61). He had completed a draft of the chapter on reversion and two others on inheritance on 1 April 1863 (see ‘Journal’ (Correspondence vol. 11, Appendix II)).

The letter in which Scott sent this information has not been found. Scott had been working on the sexuality of cryptogams; his observations were later published as Scott 1864c (see Correspondence vol. 12, letter from John Scott, 12 [February 1864]). In Scott 1864c, p. 195, Scott described the growth of a plant that he believed was a successful cross between two species of the clubmoss, Selaginella.