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Darwin Correspondence Project

To Henry Denny   23 March [1865]1

Down Bromley | Kent

March 23d

Dear Sir

I had not heard before in answer to my letter of Jan. 28th & now thank you sincerely for taking the trouble to write to me.2

I regret that you have had no opportunity to observe the lice of our various domestic animals from distant lands.— I am much interested by what you tell me about the aperea, for I had come to the conclusion from other reasons that the aperea is not the progenitor of our guinea-pigs.—3

I am not sure what you mean by the “stock-dove”: properly that means the C. œnas; our domestic pigeon being C. livia, which has an enormous range.—4 C. œnas has a wide range, but how wide I do not know; but as your specimen had not its habitat marked this is unimportant.—

If you thought it worth while to address a letter to the Council of the Zoolog. Soc. stating in some detail what you required, it is probable that proper orders would be issued; but I fear you wd. have to pay frequent visits to the Gardens to get the orders attended to, but I daresay you would receive some specimens.— Mr Sclater wd. feel interest in regard to the Birds—5

With my best thanks | I remain Dear Sir | Your’s faithfully | Ch. Darwin


The year is established by the relationship between this letter and the letter to Henry Denny, 28 January [1865].
See letter to Henry Denny, 28 January [1865]. The letter from Denny has not been found.
In July 1844 CD had sent Denny specimens of lice taken from a Cavia aperea or wild guinea-pig. In his Beagle ‘Catalogue for animals in spirits of wine’ (Down House MS), CD had noted that it would be interesting to compare these specimens with the lice of a European domestic guinea-pig to observe whether lice had been altered by transportation or domestication (Notebook 63.1, entry 646; see also R. D. Keynes ed. 2000, p. 340). Denny found the specimens to be a different genus and species from the lice on the domestic variety of guinea-pig, which led him to doubt that the wild guinea-pig could be the progenitor of the domestic guinea-pig (see Correspondence vol. 3, letter to Henry Denny, 12 August [1844], and letter from Henry Denny, 30 October 1844). See also letter to Henry Denny, 17 January [1865] and nn. 2 and 5, and letter from Henry Denny, 23 January 1865. CD’s conclusion that C. aperea was not the parent form of the domestic guinea-pig is discussed briefly in Variation 2: 152.
CD discussed the possible relationship and crosses between Columba oenas and C. livia, or what he also called the rock pigeon, in Variation 1: 183, 193 n. See also J. A. Secord 1981, pp. 179–82.
Philip Lutley Sclater was secretary of the Zoological Society of London from 1860 to 1903. He was an acknowledged expert on birds (DSB).


Interested by HD’s information on aperea; CD had concluded that it was not the progenitor of domestic guinea-pigs.

Is unsure what HD means by "stock-dove"; properly this is Columba oenas and the domestic pigeon is C. livia.

Suggests that the Zoological Society might arrange for some specimens [unspecified] to be supplied from the Gardens.

Letter details

Letter no.
Charles Robert Darwin
Henry Denny
Sent from
Source of text
American Philosophical Society (Mss.B.D25.120)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 2435,” accessed on 16 September 2019,

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