Enthusiastic about JS's work on Passiflora self-incompatibility.
CD quotes JS on rostellar pollen germination [in "Fertilisation of orchids", Collected papers 2: 77–8]. H. Crüger attributes it to ants' carrying stigmatic secretion to pollen.
Homomorphic cowslip seedlings are, sadly, showing variation.
Down Bromley Kent.
Your letter, as every one you have written, has greatly interested me. If you can show that certain individual Passifloras, under certain known or unknown conditions of life, have stigmas capable of fertilisation by pollen from another species, or from another individual of its own species, yet not by its own individual pollen, (its own individual pollen being proved to be good by its action on some other species) you will add a case of great interest to me; & which in my opinion would be quite worth your publication. I always imagined that such recorded cases must be due to unnatural conditions of life; & think I said so in Origin. I am not sure that I understand your result, whether it means what I have above obscurely expressed. If you can prove the above, do publish; but if you will not publish I earnestly beg you to let me have the facts in detail; but you ought to publish for I may not use facts for years.—
I have been much interested by what you say on the Rostellum exciting pollen
to protrude tubes; but are you sure that the rostellum does
excite them? would not tubes protrude if placed on part of column or base of petals
&c., near to the stigma?— Please look at Cottage Gardener (or
J. of Hort) to be published tomorrow week for letter of mine, in which I
venture to quote you, & in which you will see curious fact about unopened orchid
flowers setting seed in W. Indies. D
What a curious case your Gongora must be: could you spare me
one of largest capsule: I want to estimate number of seed, & try my hand if I
can make them grow. This, however, is foolish attempt; for D
You will see that I am better; but still greatly fear that I must have compulsory holiday.
With sincere thanks & hearty admiration at your powers of observation.— Dear Sir | Yours sincerely | C. Darwin
My poor P. Scotica, look very sick, which you so kindly sent me.—
- f1 4060.f1The year is established by the reference to the letter from John Scott, 21 March .
- f2 4060.f2Letter from John Scott, 21 March .
- f3 4060.f3Following a discussion of genera, including Passiflora, in which some species had been found to be more easily fertilised by the pollen of another species than their own pollen (Origin, p. 251), CD wrote:
Although the plants in these experiments appeared perfectly healthy, and although both the ovules and pollen of the same flower were perfectly good with respect to other species, yet as they were functionally imperfect in their mutual self-action, we must infer that the plants were in an unnatural state.
- f4 4060.f4Scott published the results of his experiments on Passiflora in Scott 1864d; CD cited Scott's paper in Variation 2: 137. Although CD wrote drafts of the chapters on inheritance for Variation (Variation 2: 1--84) between 23 January and 1 April 1863 (see `Journal' (Correspondence vol. 11, Appendix II)), the work was not published until 1868.
- f5 4060.f5See letter from John Scott, 21 March  and nn. 7 and 8.
- f6 4060.f6See letter to Journal of Horticulture and Cottage Gardener, [17--24 March 1863].
- f7 4060.f7See letter from Hermann Cr¨uger, 23 February 1863.
- f8 4060.f8See Orchids p. 324 n.
- f9 4060.f9See letter from John Scott, 21 March .
- f10 4060.f10Joseph Dalton Hooker visited Down House on 22 March 1863 (see letter from J. D. Hooker, [24 March 1863]).
- f11 4060.f11Letter from Hermann Cr¨uger, 23 February 1863.
- f12 4060.f12CD refers to seedlings raised from crossing experiments with cowslips (Primula veris) carried out in 1862 (see DAR 157a: 77 and DAR 108: 70; see also Correspondence vol. 10). These experiments are described in `Illegitimate offspring of dimorphic and trimorphic plants', pp. 423--30, where CD notes that the `short-styled form of the cowslip, when self-fertilized, does not transmit the same form nearly so truly as does that of P. sinensis.' With a single exception, CD had found that both long- and short-styled plants of P. sinensis (the Chinese primrose), produced only own-form plants when pollinated with own-form pollen (see letter to John Scott, 20 [February 1863]).
- f13 4060.f13Scott had sent CD specimens of Primula scotica in January (see letter from John Scott, 6 January 1863).