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
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
- ALS 4pp
Please cite as
Darwin Correspondence Project, “Letter no. 3285,” accessed on 27 March 2023, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-3285.xml
Also published in The Correspondence of Charles Darwin, vol. 9