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Darwin Correspondence Project

To J. D. Hooker   13 October [1861]

Down Bromley Kent

Oct 13th

My dear Hooker.

Thanks for note.1 It seems that I cannot exhaust your goodnature. I have had the hardest day’s work at Catasetum & buds of Mormodes, & believe I understand at last mechanism of movements & function.— Catasetum is beautiful case of slight modification of structure leading to new function. I never was more interested in any subject in my life, than in this of Orchids.— I owe very much to you.—

Now for points to attend to.—

Does viscid surface of rostellum (or gland) in Cycnoches or Mormodes project beyond stigmatic cavity; or does it not lie (as in bud & as in mature Catasetum) within roof of stigmatic cavity. But you must not touch, you must judge by looks.—

2d. First touch base of Column; then touch basal edge of a curtain which depends (I suppose) in front of stigmatic cavity; then touch round smooth surface in middle over stigmatic cavity; & lastly touch either of two slight prominent knobs on side of stigmatic cavity: This latter point, I expect, will be sensitive & will cause pollinia to be ejected with force, gland foremost.— I judge from Catasetum: Which is the sensitive point I want most to know. Touch lightly with needle or bristle; & secondly whether gland-end is not projected foremost?— I cannot believe that pollinia would hit own stigma???   I can imagine that it may fertilise itself & this would be most important point for me.

I have written to Mr Veitch begging him to let me buy flowers, if any more open & I will send Parslow up to carry them down in hand.2 Would it not save you trouble if I were to do same i.e. send servant to Kew? that is if you can spare me a flower or two.— Perhaps this would be best for me.—

If any flower of great tribe of Arethuseæ shd. open, please remember how much I wish to see one.—3 Hearty thanks for information about vascular vessels;4 I shall do a bit more work at them.

If it does not trouble Oliver will you ask him to look once again within sack of Stanhopea; for it is not very likely that there shd. be nectar till after flower has opened for some days & been well shone on.5

Your affect. | C. Darwin

See how pretty it is; an insect could not touch sticky gland of Catasetum, from its sticky surface lying close to roof of stigmatic chamber; consequently it is projected, sticky end first, with wonderful force, right on head or shoulders of an insect crawling on the Labellum.—

Footnotes

Hooker’s letter has not been found. It was a response to queries in the letters to J. D. Hooker, 4 October [1861] and 6–7 October [1861].
James Veitch, a nurseryman in Chelsea, supplied CD with several foreign orchids. Joseph Parslow was the butler at Down House.
CD was anxious to examine species belonging to the Arethuseae tribe to compare their flower structure with that of the other major tribes of orchids. However, he was unable to obtain any specimens before the publication of Orchids (see Orchids, p. 269).
CD had asked Hooker whether the existence of ‘spiral’ vessels running up the middle of the lateral membranes forming the clinandrium in Malaxis could indicate that the membranes were modified anthers (see letter to J. D. Hooker, 4 October [1861]). Hooker’s reply has not been found. However, he apparently encouraged CD to trace the longitudinal course of the vascular tissue in this and other orchids (see letter to J. D. Hooker, 27 October [1861], and Orchids, pp. 290–2).
See letter to Daniel Oliver 8 October [1861], and letter from Daniel Oliver, [after 8 October 1861].

Bibliography

Orchids: On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing. By Charles Darwin. London: John Murray. 1862.

Summary

Orchid anatomy. Catasetum exemplifies slight modification of structure leading to new structure.

Letter details

Letter no.
DCP-LETT-3285
From
Charles Robert Darwin
To
Joseph Dalton Hooker
Sent from
Down
Source of text
DAR 115: 118
Physical description
4pp

Please cite as

Darwin Correspondence Project, “Letter no. 3285,” accessed on 20 June 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-3285.xml

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

letter