To J. D. Hooker   4 October [1861]

Down Bromley Kent

Oct 4th.

My dear Hooker

Will you have kindness to read enclosed & look at diagram.— Six words will answer my question.— It is not an important point; but there is to me an irresistible charm in trying to make out homologies.— You know the membranous cup or clinandrum, in many orchids, behind the stigma & rostellum: it is formed of membrane which unites the filament of the normal dorsal anther, with the edges of the pistil. The Clinandrum is largely developed in Malaxis, & is of considerable importance in retaining the Pollinia which, as soon as flower opens, are quite loose.—

The appearance & similarity of tissues &c at once give suspicion that these lateral membranes of the clinandrum are the two other & rudimentary anthers, which in Orchis & Cephalanthera &c &c exist as mere papillæ. Here developed & utilised.—

Now for my question; exactly in middle of filament of normal anther, & exactly in middle of the lateral membranes of clinandrum, & running up to same height, are quite similar bundle of spiral vessels; ending upwards almost suddenly.— Now is not this structure good argument that I interpret the homologies of sides of Clinandrum rightly?1

Yours affect. | C. Darwin

I find that the great Bauer does not draw very correctly!! and good Heavens what a jumble he makes on functions.2

[Enclosure]

True Dorsal anther in bud with pollinia seen within cells.

diagram

(Back of Clinandrum of Malaxis, laid out flat.)

Endorsement: ‘/61’

1
Hooker’s response has not been found, but see the letter to J. D. Hooker, 6–7 October [1861]. CD discussed the homologies of orchid flowers in the concluding chapter of Orchids and included a sentence describing the results of his dissection of Malaxis (Orchids, pp. 298–9): In the young flower-bud of Malaxis paludosa, the close resemblance between the membranes of the clinandrum and the fertile anther, in shape, texture, and in the height to which the spiral vessels extend, is most striking: it is impossible to doubt that in these two membranes we see two rudimentary anthers. Malaxis paludosa is a synonym of Hammarbya paludosa, the bog orchid.
2
Franz Andreas Bauer, botanical illustrator at the Royal Botanic Gardens, Kew during the period of Joseph Banks’s superintendence, had prepared a major work illustrating orchids and describing the functions of the flower parts (Bauer 1830–8). CD had recently borrowed the book from Hooker. See letters to J. D. Hooker, [11 August 1861], 6 September [1861], and 24 September [1861]. Several of the illustrations in Orchids were copied from Bauer’s drawings.

Manuscript Alterations and Comments

1.5 normal] above del ‘true’
1.6 The Clinandrum] above del ‘It’

Please cite as “DCP-LETT-3276,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-3276