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Darwin Correspondence Project

To Daniel Oliver   17 February [1864]1

Down Bromley | Kent

Feb 17

Dear Oliver

Many thanks for the Epacrids which I have kept as they will interest me when able to look thro’ the microscope.2

Dr Cruger has sent me the enclosed paper with power to do what I think fit with it.3 He wd evidently prefer it to appear in the Nat. Hist. Review.4

Please read it & let me have your decision pretty soon. Some Germanisms must be corrected.— whether wood cuts are necessary I have not been able to pay attention enough to decide. If you refuse please send it to Linn. Soc. as communicated by me.5 The paper has interested me extremely & I shall have no peace till I have a good boast. The sexes are separate in Catasetum which is a wonderful relief to me as I have had two or three letters saying that the male C. Tridentatum seeds.6 It is pretty clear to me that 2 or 3 forms are confounded under this name   Observe how curiously nearly perfect the pollen of the female is according to Cruger7   Certainly more perfect than the pollen from the Guyana specimens described by me.8

I was right in the manner in which the pollen adheres to the hairy back of the humble bee & hence the force of the ejection of the Pollinia.9 I am still more pleased that I was right about insects gnawing the fleshy labellum. This is important as it explains all the astounding projections on the labellum of Oncidium phalænopsis &c.10

Excuse all my boasting. It is the best medicine for my stomach. Tell me whether you mean to take up Orchids as Hooker said you were thinking of doing.

Do you know Coryanthes with its wonderful bucket of water? See what Cruger says about it.11 It beats every thing in Orchids.

Dear Oliver | yours sincerely | Ch. Darwin


The year is established by the reference to the draft of Crüger 1864 (see n. 3, below).
CD refers to specimens of the Epacridaceae, a family of shrubs and trees, primarily from Australia.
Hermann Crüger had sent CD a manuscript of Crüger 1864, along with associated orchid and insect specimens (see letter from Hermann Crüger, 21 January 1864 and nn. 6–9, 26, and 27).
See letter from Hermann Crüger, 21 January 1864 and n. 9. Daniel Oliver was one of the botany editors for the Natural History Review.
Oliver sent the paper, later published as Crüger 1864, to George Bentham, president of the Linnean Society (see letter from Daniel Oliver, 18 February 1864).
See letter from Hermann Crüger, 21 January 1864 and n. 17. Crüger noted that the male, female and intermediate forms of Catasetum tridentatum had been described well by Darwin, and that he had been able ‘to verify the supposition of Darwin to its fullest extent’ (Crüger 1864, pp. 127, 129). For arguments that the male C. tridentatum produced seeds, see the letter from Hermann Crüger, 21 January 1864 and n. 20, and Correspondence vol. 11, letter from H. F. Hance, 10 May 1863, and letter to J. D. Hooker, 3 August [1863]. For CD’s discussion of C. tridentatum seed-production and of Crüger’s conclusions, see ‘Fertilization of orchids’, p. 154 (Collected papers 2: 151), and Orchids 2d ed., pp. 197 and 200.
Crüger 1864, pp. 127–9. See ‘Fertilization of orchids’, p. 154 (Collected papers 2: 151), and Orchids 2d ed., pp. 200 and 202, for CD’s references to Crüger’s observation.
See ‘Three sexual forms of Catasetum tridentatum’, pp. 240, 242–3 (Collected papers 2: 66, 67, 69), and Orchids, pp. 240–4.
See letter from Hermann Crüger, 21 January 1864 and n. 5. In Orchids, pp. 234–5, CD had described the pollination of Catasetum tridentatum flowers, in which the pollinia were ejected when a structure he called the antenna was touched by an insect; see also ‘Three sexual forms of Catasetum tridentatum’, pp. 247–8 (Collected papers 2: 69), and Crüger 1864, p. 129 and plate IX, figures 1–3. See ‘Fertilization of orchids’, p. 154 (Collected papers 2: 151), and Orchids 2d ed., p. 207. CD also described Catasetum pollination in ‘Three forms of Lythrum salicaria’, p. 194 (Collected papers 2: 126), and in Origin 4th ed., pp. 230–1.
CD speculated in Orchids, pp. 282–5, that insects were attracted to food within the labellum; Crüger observed that when humble-bees gnawed off the interior lining of the labellum of Catasetum tridentatum, the pollinia attached to their backs (Crüger 1864, pp. 129–30). CD noted Crüger’s observation in Origin 4th ed., pp. 230–1, ‘Fertilization of orchids’, p. 154 (Collected papers 2: 151), and Orchids 2d ed., p. 270.
CD had mentioned the secretion of a fluid (water with some nectar) into the hollowed end of the labellum of Coryanthes in Orchids, pp. 277–8. Crüger described his observations of the role of the bucket in the pollination of C. macrantha by humble-bees; the viscid disc of the pollen-mass was secured onto the back of the bee as it tried to force its way out through a passage after falling into the nectar; when the bee next fell into the bucket of the same or another flower, the pollen was deposited on the stigma as it tried to leave (Crüger 1864, p. 130). CD referred to Crüger’s observation in ‘Fertilization of orchids’, p. 157 (Collected papers, 2: 153–4); he quoted him at length in Orchids 2d ed., pp. 173–6, and included a new woodcut of C. speciosa on p. 174 (see drawing of C. speciosa in DAR 70: 149). CD also mentioned Crüger’s observations in Origin 4th ed., pp. 229–31. See also letter from Hermann Crüger, 21 January 1864 and n. 3.


Sends Hermann Crüger’s paper ["A few notes on the fecundation of orchids and their morphology", J. Proc. Linn. Soc. Lond. (Bot.) 8 (1865): 127–35] for publication.

"Boasts" of confirmation that sexes are separate in Catasetum.

Letter details

Letter no.
Charles Robert Darwin
Daniel Oliver
Sent from
Source of text
DAR 261.10: 58 (EH 88206041)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4410,” accessed on 19 June 2019,

Also published in The Correspondence of Charles Darwin, vol. 12