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Darwin Correspondence Project

To W. D. Fox   9 March [1863]

Down Bromley Kent

March 9th

My dear Fox

I have just been quoting in my M.S. on your authority from an old letter that you crossed White Muscovy Drake with slate-coloured duck & that the young were always pied black & white like the common or aboriginal breed.—1 I have many analogous facts in common Ducks, fowls, & pigeons & the case interests me much. Now can you tell me do the White Musk & Slate-coloured musk, (when not crossed) each breed quite or nearly true?

Again in same letter I have quoted that “12 white ewes of Mr Woodd’s had 23 coal-black lambs by a Ram that had a small patch of black only”.2 Can you tell me what breed these ewes were? Was Ram of same breed? Do you know how big & where the black patch on ram was?—

I should almost expect that if two very different breeds of white sheep were crossed there would be some tendency to dusky lambs; & so with horns, if two hornless breeds were crossed; but I know not where to enquire. I am even inclined to suspect that there is a tendency to a return to primordial wildness in hybrids between two domestic species.—

I enjoyed much seeing you in London.—3 My London trip did me some good; but I have since had a very bad fortnight; & Emma declares, I fear with truth, that we must all go for 6 or 8 weeks to Malvern.4

My dear old friend | Yours ever sincerely | C. Darwin


The letter from Fox has not been found; however, see Correspondence vol. 6, letter to W. D. Fox, 3 January [1856], in which CD thanked Fox for ‘particulars on the eggs and colour of the Muscovy Ducks & sheep’ (see also n. 2, below). CD wrote a draft of the section of Variation dealing with inheritance (Variation 2: 1–84) between 23 January and 1 April 1863 (see ‘Journal’ (Correspondence vol. 11, Appendix II)); the crosses conducted by Fox are briefly mentioned in Variation 2: 40.
This information, incorporating corrections sent by Fox, is given in Variation 2: 30–1. The reference is probably to Basil George Woodd, Fox’s father-in-law.
CD stayed at 6 Queen Anne Street, London, the home of his brother Erasmus Alvey Darwin, between 4 and 14 February 1863. He met Fox there on 13 February (see letter to W. D. Fox, [10 February 1863], and letter from W. D. Fox, [11 February 1863]).
CD refers to James Manby Gully’s hydropathic establishment in Great Malvern, Worcestershire. CD and Fox discussed the benefits of hydropathy and the treatment offered at Gully’s establishment at length in 1849 (see Correspondence vol. 4); Fox had also undergone treatment there. On the state of CD’s health, see also the letter to H. W. Bates, 4 March [1863], n. 10


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Has quoted WDF on crossing white and slate muscovy ducks [Variation 2: 40]. When not crossed, do these breed true?

Will also quote him on Mr Woodd’s white ewes that produced black lambs by a ram with only black spots [Variation 2: 30].

Letter details

Letter no.
Charles Robert Darwin
William Darwin Fox
Sent from
MR 10 63
Source of text
Christ’s College Library, Cambridge (MS 53 Fox 138)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 4033,” accessed on 26 March 2023,

Also published in The Correspondence of Charles Darwin, vol. 11