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Darwin Correspondence Project

To Henry Denny   3 June [1844]

Down Bromley | Kent

June 3d

Dear Sir

I am much obliged for your note.— You are at perfect liberty to mention Mr Martials story— I forget whether I said, he was a surgeon of a whaler, but a rather worthless, slightly educated man; perhaps, however, in some respects his story is less likely from this cause to have been invented.—1

I myself do not think our supposed knowledge of having come from one stock ought to enter into any scientific reasoning. Anyhow the inhabitants of eastern & western Europe have different species of intestinal worms.—

I fear I cannot at present offer to search for the specimens in Spirits, but if you will inform me, (supposing I do not send them before hand) at the latest period, when you absolutely require them for comparison, I will get them out of a chaos of specimens.—2

Believe me | dear Sir | Yours sincerely | C. Darwin

P.S. | I have been informed that the Pediculi generally, if not invariably, perish on wild animals in their passage to England, or in captivity. This, perhaps, may bear on their death in Mr Martial’s story. A slight fever, or even a broken limb with no fever has been known to cause the evacuation of the intestinal worms in a person—facts which show by what slight changes in constitution parasites are affected.


While on Chiloé in 1834 CD made the following entry in his Beagle zoological diary: Mr. Martial, a surgeon of an English Whaler assures me that the Lice of the Sandwich Islanders … if they strayed to the bodies of the English in 3 or 4 days died … If these facts were verified their interest would be great.— Man springing from one stock according his varieties having different *species of [added, pencil ] parasites.— It leads one into [after del illeg ] many reflections.— (DAR 31.2: 315). The last sentence was subsequently deleted in pencil and the passage beginning ‘If these facts’ to the end crossed in pencil. The pencil alterations appear to have been made after the voyage. The account was used later in Descent 1: 219.
See letter to Henry Denny, 20 January [1844], in which CD offered to send Denny his sucking lice specimens. CD sorted his collections in July and provided Denny with specimens (‘Journal’; Correspondence vol. 3, Appendix II).


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

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.


Discusses intestinal worms among humans.

Comments on origin of human races.

Letter details

Letter no.
Charles Robert Darwin
Henry Denny
Sent from
Source of text
American Philosophical Society (Mss.B.D25.35)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 755,” accessed on 17 April 2024,

Also published in The Correspondence of Charles Darwin, vol. 3