To G. H. K. Thwaites   29 July [1863]1

Down. | Bromley. | Kent. S.E.

July 29th

My dear Thwaites

I thank you sincerely for the seed of Limnanthemium, which I have planted, & if the plants will flower, they will be a treasure to me.2

The view on the conjugation of Algæ is familiar to me from a pamphet which you sent me many years ago, & which records a remarkable double embryo in Fuchsia to which I have lately had to refer.3 This view of Algæ prefiguring the higher stages of reproduction has since reading your paper always seemed probable to me.—

I was glad to see the Cassia & to hear of the two forms of anthers in the same flower.4 This class of gradation always seems to me very interesting. What a curious flower that of the Cassia. Mr Glennie ought to watch it & see how insects visit it; I should expect that the pistil would change its position during inflorescence.5 You ask for my “carte de visite”; but I have never been done; I can only send you a rather poor small photograph made by my son.—6

With very sincere thanks & good wishes, | believe me | Yours very sincerely | Ch. Darwin

1
The year is established by the relationship between this letter and the letter from G. H. K. Thwaites, 8 June 1863.
2
Thwaites had sent CD seed of Limnanthemum indicum, a species with dimorphic flowers (see letter from G. H. K. Thwaites, 8 June 1863).
3
CD refers to the letter from G. H. K. Thwaites, 8 June 1863, and to Thwaites 1848, which suggested parallels between reproduction in lower and higher plants. There is an annotated presentation copy of Thwaites 1848 in the Darwin Pamphlet Collection–CUL. CD cited Thwaites’s account of a double embryo in Fuchsia coccinea (Thwaites 1848, pp. 163–4) in Variation 1: 391; he prepared a draft of the chapter of Variation in which this reference appears between 21 December 1862 and 23 January 1863 (see Correspondence vol. 10, and this volume, ‘Journal’ (Correspondence vol. 11, Appendix II)).
4
See the enclosure to the letter from G. H. K. Thwaites, 8 June 1863. In his letter of 8 June 1863 Thwaites sent CD a letter that he had received from Samuel Owen Glenie; Glenie’s letter contained specimens and descriptions of stamens from a flower of Cassia. CD had already learned from Joseph Dalton Hooker that species of Cassia had two forms of anther in the same flower (see Correspondence vol. 10, letter from J. D. Hooker, [12 October 1862], and letter to J. D. Hooker, 14 [October 1862]).
5
CD thought that the occurrence of differently coloured anthers in the same flower might be a guide to functional dimorphism, representing a gradation towards structural dimorphism (see Correspondence vol. 10, letter to J. D. Hooker, 22 [August 1862] and n. 14). Moreover, having noticed in some of the Melastomataceae that the pistils changed their positions as the flowers became older, he considered that this structural change might be accompanied by a functional change with respect to the pollen from the two sets of anthers (see, for instance, Correspondence vol. 10, letter to Asa Gray, 16 February [1862], and letter to J. D. Hooker, 15 [May 1862]).
6
CD apparently refers to the photograph taken by William Erasmus Darwin in April 1861, which is reproduced as the frontispiece to Correspondence vol. 9 (see ibid., letter to Asa Gray, 11 April [1861] and n. 19).

Manuscript Alterations and Comments

1.2 if] interl
2.3 to which … refer.] interl

Please cite as “DCP-LETT-4256,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-4256