PHG's hypothesis [regarding the self-fertilising mechanism of Stanhopea] may prove quite true, but CD suggests that PHG should observe another spike to make sure. CD will observe his Stanhopea if it flowers.
Down. | Bromley. | Kent. S.E.
My dear Sir
If you could prove the truth of your hypothesis, it would be extremely curious
& quite new. It certainly seems very suspicious your
having found the pollinium attached to the horns of the labellum so often. I am prepared
to believe anything of these wonderful productions. But if I were in your place, I would
wait till I could observe another spike & then you would, I have no doubt,
definitely prove the case. Why I sh
Nevertheless your case may prove quite true; the dried labellum seems very thin as if it had been flexible.— It is really a very curious case.— I have some Stanhopeas in my Stove (I know not what species) but I fear they will not flower this summer; should they do so, I will observe them & communicate the result to you.—
If you thought fit to communicate your facts now to any periodical, it might induce others to observe; but many persons are such bad observers that I doubt whether you would profit by it.—
I would suggest to you to get to know (if you do not already do so) the appearance of the viscid matter from the stigma, which abounds with isolated elongated cells, called by Brown utriculi: these I find never present in viscid matter of Rostellum; & when these parts are close, it is important to distinguish them.— You could have thus probably told whether the fluid which exuded from your decaying flowers was a true stigmatic secretion.
I heartily hope your pretty little discovery will prove good & true.—
My dear Sir | Yours very sincerely | C. Darwin
- f1 4205.f1The year is established by the relationship between this letter and the letter from P. H. Gosse, 4 June 1863.
- f2 4205.f2See letter from P. H. Gosse, 4 June 1863.
- f3 4205.f3J. D. Hooker 1854c.
- f4 4205.f4No letter from Hooker containing this information has been found; however, see Correspondence vol. 9, letter to J. D. Hooker, 15 [October 1861].
- f5 4205.f5Stanhopea appears on CD's lists of hothouse plants (Correspondence vol. 11, Appendix VI). CD did not succeed in pollinating Stanhopea until the following year (see Correspondence vol. 12, letters to J. D. Hooker, 22 October  and 3 November ). See also `Fertilization of orchids', p. 153 (Collected papers 2: 150).
- f6 4205.f6See letter from P. H. Gosse, 4 June 1863 and n. 3.
- f7 4205.f7Robert Brown 1833b, pp. 710--11; CD's abstract of this paper is in DAR 74: 169--74. There is also a presentation copy of a slightly modified preprint of this paper (Robert Brown 1831a) in the Darwin Pamphlet Collection--CUL.