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Darwin Correspondence Project

To Daniel Oliver   27 May [1861]1

Down. | Bromley. | Kent. S.E.

May 27th

My dear Sir

Will you show this note to Mr Crocker & ask him if he is inclined to try a little experiment for me.—2 Vinca major I believe never seeds in England & is said never to seed in Germany; & I find pollen so placed it could never get on stigma without insect aid.— I have pot of Vinca major & I have passed fine bristle between anthers (not cutting or touching the flowers) in same way as proboscis of moth would pass to nectary, near the sides of the corolla; pollen sticks to bristle & a bristle thus covered from pollen of one flower is used for another flower.— I did this & I have 4 or 5 fine pods swelling, whereas every other seed-vessel shanked off soon after corolla dropped.—3

Now will Mr Crocker do this (& it will not take him 2 minutes) for any exotic Vincas, which naturally have never seeded; mark the 12 dozen flowers thus treated, & hereafter let me know whether pods swelled & whether seed was obtained.—

My apocynum (or fly-catcher) is coming up; I thought it was as dead as mutton: I have been trying Vinca in preparation for this Plant.—

You once told me that Mr Crocker liked experiments; if so I wish he would insert fine brush, like a Bee into a few exotic Polygalas which do not naturally seed & mark flowers & see if pods swell; I suspect they require insect agency. By the way you have not sent me P. farinosa; I daresay you have been so busy that you forgot it.—4

I beg & pray you not merely to acknowledge this.

Yours most sincerely | C. Darwin

I am surprised to find Cowslips utterly sterile without aid.— bears on origin of Oxlips.—5


Dated by the relationship to the letter to Daniel Oliver, 1 May [1861].
Charles William Crocker was the foreman of the propagating department at the Royal Botanic Gardens, Kew. Oliver, professor of botany at University College London, worked in the herbarium and served as the librarian at Kew.
CD described this experiment in more detail in his letter to the Gardeners’ Chronicle, [before 15 June 1861].
CD asked Oliver to send him a specimen of Primula farinosa in the letter to Daniel Oliver, 1 May [1861]. A note in the margin of the letter, presumably in Oliver’s hand, reads: ‘These have not come out yet.’
CD was experimenting with primroses and cowslips in connection with his investigation of the dimorphic condition of their pistils and stamens. He described the results of his study in a paper read before the Linnean Society of London in November 1861 (see Collected papers 2: 45–63). Having shown that cowslips required insect agency to effect pollination and set seed, CD advocated the view that oxlips were produced among the progeny of cowslips only as a result of cross-pollination with primroses (ibid., pp. 60–1).


Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.


Requests that exotic species of Vinca, which never set seed at Kew, be fertilised by pressing a fine bristle between anthers as a moth would its proboscis.

Asks that Primula farinosa be sent.

Letter details

Letter no.
Charles Robert Darwin
Daniel Oliver
Sent from
Source of text
DAR 261.10: 8 (EH 88205992)
Physical description
ALS 4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 3161,” accessed on 21 April 2024,

Also published in The Correspondence of Charles Darwin, vol. 9