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Darwin Correspondence Project

From J. D. Hooker   [10 March 1865]1



Dear Darwin

I forgot to tell you that Currey asked me to ask you,2 what you wished about the execution of the woodcuts,—3 he says there was something unsatisfactory about the last. Will you write straight to him about them

F. Currey Esq

3 New Square   Lincolns Inn

W. C.

he wants to put them in hand at once.

Thomson has gone over Scott’s paper.4 & the enclosed is his conclusion;5 he is a scientific arithmetician & would I am sure solve the difficulty if soluble; the Denominators are obviously arbitrary & useless.6

I have read through Scott’s paper, & am amazed at his industry & ability, but in its present state the paper is not fit for publication, & I think the experiments should have been repeated—7 his discord with Gærtner either shakes the whole value of his system of experimentation, or shows that similar experiments give different results, or that one of the observers is wrong.8

You are the only judge of the value of such a paper:— it is awfully tedious to read. Much of it is simply a repetition of the Tables, & that part might be shortened—perhaps.

Ever yrs affec | Jos D Hooker

I return Scotts’ paper.

Currey wants to know, who you would wish to execute the wood engravings—

See that proofs are sent to you of them


The date is established by the relationship between this letter and Hooker’s visit to Down House between 4 and 6 March 1865 (see n. 2, below), and by the relationship between this letter and the letter to J. D. Hooker, 16 [March 1865]; the intervening Friday was 10 March.
Frederick Currey was botanical secretary of the Linnean Society (Gage and Stearn 1988, p. 59). Hooker presumably intended to convey Currey’s message when he visited Down House between 4 and 6 March 1865 (Emma Darwin’s diary, DAR 242).
The woodcuts were for ‘Climbing plants’, an abstract of which was read at the Linnean Society on 2 February 1865; Currey was evidently preparing the paper for publication in the society’s journal. The paper included thirteen woodcuts. In ‘Climbing plants’, p. 49 n., CD wrote that figures 5 to 13 were drawn from living plants by his son, George Howard Darwin; in Climbing plants 2d ed., p. v, CD wrote that all the illustrations were drawn by George.
The references are to Thomas Thomson and to a draft of Scott 1867. John Scott sent the manuscript and a separate (missing) letter on the same subject to CD from Calcutta on 4 January 1865 (see letters from John Scott, 20 January 1865 and 21 July 1865); CD may have given Hooker the manuscript during his visit to Down House between 4 and 6 March 1865. Thomson was based at the Royal Botanic Gardens, Kew, while collaborating with Hooker on material for a new Flora Indica (see L. Huxley ed. 1918, 2: 12). There is an annotated copy of Scott 1867 in the Darwin Pamphlet Collection–CUL.
The enclosure has not been found; CD may have forwarded Thomson’s criticisms to Scott (see letter to J. D. Hooker, 16 [March 1865]).
In his published paper, in order to show the ‘comparative fertility of the different unions’ (Scott 1867, tables 2–7, pp. 153–62), Scott counted the number of capsules and seeds resulting from self-pollination in a species or variety of Verbascum, and the number resulting from cross-pollination with other species or varieties. He then calculated the number of seeds that would have been produced from each cross if twenty capsules had been formed and divided the number of seeds produced by cross-pollination between the various taxa by the number of seeds produced by a self-pollinated plant, and multiplied that figure by 1000. This yielded a figure for comparative fertility ranging from 1000 for a self-pollinated Verbascum species to 242 for the least fertile cross between two different species of Verbascum. In his draft manuscript, Scott may have made an error in the method of this last step in the calculation. In the letter from John Scott, 21 July 1865, Scott apologised for the ‘singular blunderings’ in his calculations.
In his letter of 21 July 1865, Scott revealed to CD that his manuscript had been written on the ship to India, from notes on experiments that he had made on Verbascum at the Royal Botanic Garden, Edinburgh (see n. 8, below). There is no indication in the published paper (Scott 1867) that further experiments were made in India. Scott sailed for India on 28 August 1864, arriving 21 December 1864 (see Correspondence vol. 12, letter to J. H. Balfour, 15 September [1864], and this volume, letter from John Scott, 20 January 1865).
The reference is to Karl Friedrich von Gärtner’s experiments with Verbascum in which crosses between differently coloured varieties of the same or of different species were found to be less fertile than parallel crosses between similarly coloured varieties (Gärtner 1844 and 1849). CD discussed these experiments in Origin, pp. 270–1, and encouraged Scott to attempt these and similar experiments in the letters to John Scott, 19 November [1862] and 11 December [1862] (Correspondence vol. 10). CD also sent Scott a digest of Gärtner’s experiments (see Scott 1867, p. 164). On the importance of Gärtner’s work for CD’s theory of natural selection, see Correspondence vol. 10, Appendix VI. Scott’s experiments on Verbascum were made in 1863 and 1864 (see, for example, Correspondence vol. 11, letter from John Scott, 21 September [1863], and Correspondence vol. 12, letter from John Scott, 16 May [1864]). Scott’s published conclusion from these experiments was that there was no clear relationship between affinities of colour and degrees of fertility in crossing varieties of distinct species of Verbascum, but that with varieties of the same species, similarly coloured varieties were more fertile when crossed than differently coloured varieties (see Scott 1867, pp. 165–6, 171–2). CD discussed Scott’s results in Variation 2: 106–7.


Thomas Thomson has gone over Scott’s paper; encloses his conclusions. Not fit for publication in present form. His experiments should have been repeated to resolve his disagreement with Gärtner.

Letter details

Letter no.
Joseph Dalton Hooker
Charles Robert Darwin
Sent from
Source of text
DAR 102: 13–14
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4782,” accessed on 25 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 13