Ɛpsilon

To G. H. K. Thwaites   26 March 1877

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Mar 26. 1877

Dear Thwaites,

I have just been looking with very great interest at the specimens which you have been so kind as to send me. The difference between the male & female is wonderful, & almost reminds me of my old friends the complemental males of certain cirripedes.1 I hope Westwood will make a very interesting paper on the subject. I wonder whether they play any part in the fertilisation of the fig,—a subject Dr Crüger in the W. Indies was beginning to attend just before his death.2

The day before yesterday I was pleased to hear some account of you in a letter from Miss North which was sent me to read by a mutual friend, & in which she speaks with having many pleasant walks with you in the evenings.3 Do you remember sending me several years ago flowers of Oxalis sensitiva in spirits? I have only just examined them, & find them beautifully trimorphic, & in addition bearing cleistogamic flowers, which to my great surprise are long-styled, mid-styled, & short-styled like the perfect flowers; & this was quite a new fact to me.4

With all good wishes for your health & with many thanks | I remain, dear Thwaites | Yours sincerely | Charles Darwin

LS

1
Thwaites’s letter has not been found, but he sent CD insects that were parasitic on fig fruit; see letter from G. H. K. Thwaites, 28 August 1877. CD discovered ‘complemental males’ in several species of Cirripedia; he observed minute males attached to the bodies of hermaphrodites, and differing greatly from them in size and structure (see Living Cirripedia (1851), pp. 231–2 and 281–93, Living Cirripedia (1854), pp. 23–30, and Newman 1993, pp. 377–81).
2
John Obadiah Westwood published on specimens of fig wasps sent to him by Thwaites in Westwood 1882, pp. 39–44, and Westwood 1883, pp. 375–8. Hermann Crüger published on figs’ requiring insects for fertilisation in Crüger 1851. Shortly before his death in 1864, Crüger was performing experiments suggested by CD to verify this (see Correspondence vol. 12, letter from Hermann Crüger, 21 January 1864).
3
In 1877, Marianne North visited Ceylon (now Sri Lanka) where Thwaites lived (ODNB); the ‘mutual friend’ was probably Joseph Dalton Hooker.
4
CD had mentioned Oxalis (the genus of woodsorrels) to Thwaites in his letter of 20 June [1862] (Correspondence vol. 10). He described specimens of Oxalis sensitiva (a synonym of Biophytum sensitivum) sent by Thwaites in Forms of flowers, p. 181, and on pp. 322–3, suggested that the three cleistogamic forms could be accounted for by the principle of correlated growth.

Please cite as “DCP-LETT-10913,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10913