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To R. D. Fitzgerald   16 July 1875

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

July 16. 75

Dear Sir

Owing to Mr Russell not having found my proper address & his subsequent absence on the Continent, I received the present of your magnificent work with its excellent illustrations, only about a week ago.1 I have now read it with much interest, & am astonished that such a work could have been prepared at Sydney. I have been particularly interested by your account of the movements of Pterostylis & Caladenia.2 Do you think it possible that the calli on the labellum are gnawed or sucked by insects?3 A careful examination of the flowers from which the pollinia have been removed by insects, would be well worth making. I daresay you have seen a good paper on the former genus in a late vol of the N. Zealand Institute.4 I have been even more interested about the closed flowers of Thelymitra, as the case is closely analogous to the equally inaccessible one of the Bee Ophrys in Europe.5 I suppose you have few coadjutors, but it would be well to ascertain whether the flowers are closed during years when the seasons are very different, & in all parts of the plant’s range. I will venture to make one other suggestion; viz with sterile species like Dendrobium hillii to try the effects of pollen taken from a distinct seedling plant, in accordance with the observations of Fritz Müller.6 I have found it almost necessary to observe insects at work to understand the meaning of the parts in orchids & on this head I see that you are a disbeliever.7 From not having been able to act in this manner I blundered about Cypripedium;8 but I do not think I have erred about the nectary of Angræcum, & Wallace has given the case of a sphinx with proboscis of sufficient length.9

With my best thanks & good wishes for your future success | I remain dear Sir | Yours faithfully | Ch. Darwin

LS

1
CD had received the first part of Fitzgerald’s Australian orchids (Fitzgerald 1875–94). See letters to Mr Russell, 26 June [1875] and 12 July 1875.
2
Fitzgerald described the genus Pterostylis, with illustrations of P. longifolia (tall greenhood) and P. baptistii (king greenhood), and the genus Caladenia (spider orchid) with an illustration of C. dimorpha (Fitzgerald 1875–94, vol. 1, part 1).
3
The ‘calli’ are glands on the labellum. CD had cited observations by Hermann Crüger of bees gnawing the labellum in orchids (see Origin 4th ed., pp. 230–1, ‘Fertilization of orchids’, p. 154 (Collected papers 2: 151), and Orchids 2d ed., p. 270.
4
Cheeseman 1872. See Correspondence vol. 21, letter from T. F. Cheeseman 27 June 1873.
5
The closed flowers of Thelymitra carnea (the pink sun orchid) were described in the introductory essay to Fitzgerald 1875–94, vol. 1, part 1: 1. The self-fertile bee ophrys (Ophrys apifera) presented a challenge to CD’s general argument that orchids were adapted for crossing between different individuals (see Orchids, pp. 63–72).
6
Fitzgerald observed that a specimen of Dendrobium hillii (now Dendrobium speciosum var. hillii; the king orchid) with around 40,000 flowers produced no seed (see Fitzgerald 1875–94, vol. 1, part 1: 2.) Fritz Müller determined that in some orchids pollen from the same plant was impotent or even harmful, whereas pollen from another plant produced seed (see Variation 2: 134–5, F. Müller 1868, and Correspondence vol. 15, letter from Fritz Müller, 1 January 1867).
7
Fitzgerald had expressed reservations about some of CD’s remarks on insect agency in Orchids; for example, ‘Mr. Darwin seems to me to lay rather too much stress on the action of large insects seeking honey by the aid of a proboscis, as agents of fertilization’ (Fitzgerald 1875–94, vol. 1, part 1: 2).
8
On Cypripedium (the lady’s-slipper orchid), see Orchids 2d ed., pp. 229–31
9
CD had described Angraecum sesquipedale (the Christmas star orchid) in Orchids, pp. 197–203, remarking that there must be moths with probosces ten or eleven inches long to reach the base of its long nectary. Alfred Russel Wallace had supported CD’s view with an illustration of a hypothetical sphinx moth (see Wallace 1867 and Correspondence vol. 15, letter to A. R. Wallace, 12 and 13 October [1867]).

Please cite as “DCP-LETT-10069,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10069