Is pleased that AdeC is interested in the Primula case ["Dimorphic condition of Primula", Collected papers 2: 45–63]. Is pursuing analogous experiments on other plants and on seedlings raised from the unions.
CD's "large work" progresses slowly owing to ill health and his work on Orchids.
CD is not surprised that AdeC is unwilling to admit natural selection – "the subject hardly admits of direct proof or evidence. It will be believed in only by those who think that it connects & partly explains several large classes of facts".
Hopes AdeC will publish on Quercus
and rejoices that he intends to return to the study of geographical distribution. No one can claim to have read AdeC's truly great work on that subject [Géographie botanique (1855)] with more care than CD.
Down. | Bromley. | Kent. S.E.
My dear Sir
I am extremely much obliged for your kind & very interesting letter. I am pleased that you are interested by the Primula case. Your questions & remarks show that you have gone to the root of the matter. I am now trying various analogous experiments on several plants & on the seedlings raised from the so-called heteromorphic & homomorphic unions; & the results (as far as I have yet seen; for the capsules are gathered, but not yet examined) are interesting; Whenever I publish I will do myself the pleasure of sending you a copy. I am particularly obliged for your information on Alkanna. I have examined the small imperfect flowers of Viola & Oxalis: the case is very different both functionally & structurally from that of Primula.—
You kindly enquire about my larger work; it does make progress, but very slowly owing
to my own weak health & ill-health in my family. I
have, also, been seduced to publish a small work on the Fertilisation of Orchids, which
has taken up nearly ten months. As M
I hope you will publish on Quercus, & I shall be most grateful for a copy; the
genus has long appeared to me preeminently interesting under the point of view to which
you refer. I am, also, rejoiced to hear that you have the
intention of again returning to Geographical Distrib
Pray believe me, my dear Sir | Yours sincerely & respectfully | Ch. Darwin
- f1 3608.f1Letter from Alphonse de Candolle, 13 June 1862.
- f2 3608.f2In January and February 1862, CD carried out crossing experiments with Primula sinensis using plants raised the previous year from the seed produced by homomorphic and heteromorphic crosses (see letters to J. D. Hooker, 7 March  and n. 10, and 23 June  and n. 4). (By `homomorphic unions', CD meant crosses in which fertilisation was effected by own-form pollen; by `heteromorphic unions', those in which it was effected by different-form pollen.) In April and May, he performed experiments on the common cowslip, P. veris, not only repeating the homomorphic and heteromorphic crosses that he had carried out in 1860 and 1861 (see letter to J. D. Hooker, 23 June  and n. 4), but also investigating the possible prepotency of different-form pollen from a polyanthus (which he considered a variety of the same species) over own-form pollen from a cowslip (see CD's notes from these experiments in DAR 157a: 76--7 and DAR 108: 70). Some of the results of CD's experiments with P. sinensis are recorded in `Illegitimate offspring of dimorphic and trimorphic plants' (a paper not included in Collected papers), which was published in 1869; the results of his experiments with P. veris are recorded in Cross and self fertilisation, p. 28, and `Three forms of Lythrum salicaria', p. 189 (see also Collected papers 2: 121--2). In the letter, CD interlined the phrase `on several plants &' (see Manuscript alterations and comments); he was engaged in crossing experiments with several members of the Melastomataceae, which he believed might exhibit dimorphism (see, for example, letter to George Bentham, 3 February , letters to J. D. Hooker, 9 February , 15 [May 1862], and 30 May , and letters to Asa Gray, 15 March  and 10--20 June ).
- f3 3608.f3See also letters to Daniel Oliver, 12 [April 1862] and 15 April , letter to J. D. Hooker, 30 May , and letter to Asa Gray, 10--20 June .
- f4 3608.f4See letter from Alphonse de Candolle, 13 June 1862 and n. 5. CD and many of his household had had influenza early in the year (see letter to J. D. Hooker, 16 January , and letter to Asa Gray, 22 January ). Horace Darwin became ill during January and had suffered bouts of ill health ever since (see letter to W. E. Darwin, 14 February ). On 12 June, Leonard Darwin was sent home from school suffering from scarlet fever (see letter to W. E. Darwin, 13 [June 1862]). In his `Journal' (see Correspondence vol. 10, Appendix II), CD recorded: `Much time wasted June & July from Leonard's illness'.
- f5 3608.f5See letter from George Bentham, 15 May 1862, and letter from Asa Gray, 18 May 1862. See also letter from J. D. Hooker, [17 May 1862], and letter to Asa Gray, 10--20 June . Candolle's name is included on CD's presentation list for Orchids (see Correspondence vol. 10, Appendix IV).
- f6 3608.f6See letter from Alphonse de Candolle, 13 June 1862.
- f7 3608.f7See letter from Alphonse de Candolle, 13 June 1862 and n. 10.
- f8 3608.f8A. de Candolle 1855. There is an annotated copy of this work in the Darwin Library--CUL (see Marginalia 1: 106).