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Darwin Correspondence Project

From P. H. Gosse   4 June 1863

Sandhurst. Torquay.

June 4. 1863.

My dear Sir,

I am exceedingly obliged for your kind & full reply.1 Will the following additional facts throw any light on the matter?

The four flowers of Stanhopea oculata became thoroughly withered & flaccid by the 1st. Inst; the fourth day after opening; yet I allowed them to remain till this morning, when I cut off the raceme just before I received your letter. As one of the germens (& this one of those that I had tried to impregnate) came away with a touch, I took it as certain that no impregnation had taken place; & so threw the whole on the rubbish heap without further examination. But on reading your remarks I thought I wd. examine them again; chiefly to see if, by piercing the stigmatic surface which had been so perfectly dry, I could find any viscosity within. Looking first at one of those to wh. I had affixed the pollen-masses by means of their viscid disk, I was surprised to see that they were half imbedded in a mass of viscous fluid. The other wh. I had treated was in precisely the same condition; the viscum having exuded copiously, & oozing in a great globule, when I used pressure with my thumb & finger lower down the column. Let this then be fact the first; that though no viscum be visible at first on the stigma, it issues copiously after the flower has faded, from the interior, at the extreme point of the rostellum.

But secondly:— A day or two after my attempt at impregnation (wh. affected only two of the four flowers), I was surprised to see the pollinia of one of the untouched flowers adhering to the point of one of the ivory-like horns of the mesochil.2 I wondered, but could not account for it, as I felt sure I had not accidentally detached & attached them in such a manner, while operating on the others. But just now, in my examination of the faded spike, I observe not only that the pollinia of that flower remain still on the tip of the horn,—but that one of the horns of the other untouched flower has rifled its own anther, & carries the pollinia in triumph on its point.

If this is accidental, it is surely a remarkable coincidence. But it suggests to me the following hypothesis. That the moveable lip of this curious flower, agitated by the wind brings the tips of the horns now & then into contact with the rostellum, so as to lift the anther, & carry away the pollinia by touching the viscid disk. That as soon as the viscum exudes from the stigmatic cavity & spreads over its surface, similar agitations of the lip would cause the pollinia to swing across the stigma, &, brushing the exuded globule of viscum, to adhere.

If this is tenable, here is a use for these extraordinary horns: tell me what you think of the thought. I regret that I was so hasty in cutting away the faded spikes; possibly, with a little more obstetric manipulation, or even an agitation of the flowers with my breath, I might have succeeded in impregnating, & in settling the point.

Tell me whether I may print this little correspondence in one of the Gardening Periodicals,3 & believe me | Yours faithfully | P. H. Gosse

I will remember the Bee Ophrys.4

P.S. If my hypothesis should be correct, will it not show that Stanhopea affords another example of self-fertilisation?5 For the horns of any blossom can rifle only its own anther, & can deposit on only its own stigma. But what an unexpected mode of proceeding! I inclose you one of the pollinia carried on the horn.


Mesochil: ‘the middle portion of the labellum of an orchid’ (OED).
Neither the correspondence, nor Gosse’s observations on Stanhopea oculeata, appear to have been published (Freeman and Wertheimer 1980).


OED: The Oxford English dictionary. Being a corrected re-issue with an introduction, supplement and bibliography of a new English dictionary. Edited by James A. H. Murray, et al. 12 vols. and supplement. Oxford: Clarendon Press. 1970. A supplement to the Oxford English dictionary. 4 vols. Edited by R. W. Burchfield. Oxford: Clarendon Press. 1972–86. The Oxford English dictionary. 2d edition. 20 vols. Prepared by J. A. Simpson and E. S. C. Weiner. Oxford: Clarendon Press. 1989. Oxford English dictionary additional series. 3 vols. Edited by John Simpson et al. Oxford: Clarendon Press. 1993–7.


Thanks CD for his full reply. Sends additional facts derived from further observation, and a possible solution.

Letter details

Letter no.
Philip Henry Gosse
Charles Robert Darwin
Sent from
Source of text
DAR 165: 77
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4203,” accessed on 23 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 11