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Darwin Correspondence Project

To J. D. Hooker   10 November [1861]

Down Bromley Kent

Nov. 10th

My dear Hooker

For the love of God help me. I believe all my work (about a fortnight) is useless. Look at this accursed diagram of the Butterfly orchis, which I examined after writing to you yesterday when I thought all my work done.1 Some of The ducts of upper sepal & upper petal run to the wrong bundles or column.— I have seen no such case. This case apparently shows that not the least reliance can be placed on course of ducts. (I am sure of my facts).

There is great adhesion & extreme displacement of parts where the organs spring from top of ovarium. Asa Gray says ducts are very early developed, & it seems to me wonderful that they should pursue this course.— It may now be said that the lateral ducts in the Labellum running into the antero-lateral ovarian bundle is no argument that the Labellum consists of 3 organs blended together.—2

In desperation (& from the curious way the base of upper petals are soldered at basal edges) I fancied the real form of upper Sepal, upper petal, & lower sepal might be as represeted by red lines;3 & that there had been an incredible amount of splitting of sepals & petals & subsequent fusion.— This seems a monstrous notion; but I have just looked at Bauer’s drawing of allied Bonatea, & there is a degree of lobing of petals & sepals, which would account for anything.4 Now could you spare me a dry flower out of your Herbarium of Bonatea speciosa, that I might soak & look for ducts; if I cannot explain the case of Habenaria, all my work is smashed. I was a fool ever to touch orchids.—

Your affect. | C. Darwin

[Enclosure]

[DIAG HERE] [DIAG HERE] Upper Sepal Upper petal Lower Sepal Labellum ovarium ovarium Post. Bundle anterior Bundle Postero-lateral Bundle antero-lateral Bundle Habenaria chlorantha Longitudinal section of ovarium.

Footnotes

See the enclosure.
CD was attempting to trace the course of the spiral vessels in orchid flowers, from the ovarium to the various parts, in an attempt to establish the homologies of orchids (see letters to J. D. Hooker, 4 October [1861], 13 October [1861], 27 October [1861], and the first letter dated 1 November [1861]). In the account he gave of orchid homologies in Orchids, CD discussed the anomaly presented by Habenaria and the allied genus Bonatea, stating that it called into question his view that the labellum was always ‘an organ compounded of one petal and two petaloid stamens’ (Orchids, p. 303).
CD drew the outermost lines, representing the ‘real form’ of the sepal and petal parts, in red crayon. The diagram has been reduced to 60% of its original size.

Bibliography

Bauer, Franz Andreas. 1830–8. Illustrations of orchidaceous plants … with notes and prefatory remarks by John Lindley. London.

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

CD fears he has misinterpreted vascularisation of butterfly orchid flowers.

Letter details

Letter no.
DCP-LETT-3315
From
Charles Robert Darwin
To
Joseph Dalton Hooker
Sent from
Down
Source of text
DAR 115: 128, 129a
Physical description
4pp, 3 diags

Please cite as

Darwin Correspondence Project, “Letter no. 3315,” accessed on 22 October 2019, https://www.darwinproject.ac.uk/letter/DCP-LETT-3315.xml

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

letter