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Darwin Correspondence Project

To Edward Blyth   4 April [1868]1

Down. | Bromley. | Kent. S.E.

Ap 4—

My dear Mr Blyth

Many thanks for your last M.S. I am very glad to hear about the colours of Hylobates.2 Unfortunately, I cannot find in Isidor Geoffroy Hist. des Anom. any statement in regard to which digits in man are most liable to syndactylism; if I cd ascertain this point your remark wd be most interesting.3 I knew about the variability of the junction of the digits in some of the species.

I have been reading over the M.S. which you sent me some weeks ago, with much interest.

Do I read correctly that the black colour in certain terns is a seasonal change either in the males or both sexes?4

I shd be particularly obliged if you wd tell me whether the Gallicrex cristatus, during the breeding season, becomes ornamented in any way to an unusual degree in comparison with other members of the same family: I want to know because you say that it is probably polygamous.5

Forgive me for asking two other questions. Do you know whether the plumes are more developed in the male ostritch than in the female?

2ndly Do you chance to know whether the male woodpecker takes a share in incubation?

With many thanks for yr never failing kindness in assisting me, believe me | yours very sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter from Edward Blyth, 5 April 1868.
See memorandum from Edward Blyth, [3 April 1868].
CD refers to Isidore Geoffroy Saint-Hilaire’s Histoire générale et particulière des anomalies de l’organisation chez l’homme et les animaux (I. Geoffroy Saint-Hilaire 1832–7); see letter from Edward Blyth, [3 April 1868] and n. 15. There is an annotated copy in the Darwin Library–CUL (see Marginalia 1: 306–16). In Variation 2: 339–41, CD had cited this work and discussed the fusion of digits with reference to Geoffroy Saint-Hilaire’s law of the affinities of homologous parts in animals.
See memorandum from Edward Blyth, [before 25 March 1868].
In his letter of 24 February 1867 (Correspondence vol. 15), Blyth had written that he suspected Gallicrex cristatus (now Gallicrex cinerea, the watercock) was polygamous.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Geoffroy Saint-Hilaire, Isidore. 1832–7. Histoire générale et particulière des anomalies de l’organisation chez l’homme et les animaux, ouvrage comprenant des recherches sur les charactères, la classification, l’influence physiologique et pathologique, les rapports généraux, les lois et les causes des monstruosites, des variétés et des vices de conformation, ou traité de tératologie. 3 vols. and atlas. Paris: J. B. Baillière.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

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


Glad to hear about colours of Hylobates.

Cannot find any statement about which digits in man are most subject to syndactylism in Isidore Geoffroy [Saint-Hilaire]’s Histoire des anomalies [1832–7].

Asks questions concerned with seasonal and sexual changes in plumage of various bird species.

Does male woodpecker share in incubation?

Letter details

Letter no.
Charles Robert Darwin
Edward Blyth
Sent from
Source of text
McGill University Library, Department of Rare Books
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6091,” accessed on 9 August 2020,

Also published in The Correspondence of Charles Darwin, vol. 16