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Darwin Correspondence Project

From Francis Galton   13 September 1871

42 Rutland Gate | London

Sept 13/71

(Address) | We are now in Yorkshire

My dear Darwin

I had proposed writing to you, in a few days time, about the rabbits when I received yr. letter.1 First, let me thank you very much for the kind care you have taken of them. Secondly,— I grieve to hear from you, that your holiday has not been so much of a success as you had hoped. so far as health is concerned2 &, thirdly, on my own part, I am glad to say, I am & have been particularly well, (except only a boil inside the ear, which hurt badly for a few days.)

To return to the rabbits:— will you kindly prevent the bucks having any further access to the does, and make away with all the young except, say, 4 or 5 as a reserve in case of continued accident in the forthcoming series of operations.3 As soon as I return to town towards end of October, I will ask you to send me the old rabbits, & will begin at once to cross-circulate every one of them.4

My present assistant (a most accomplished young M.B. in medical science) has not the manipulative skill of my old friend & I fear I shall have an undue proportion of corpses, but there must be some successes, out of the 3 does & 3 bucks that you have, & other 3 that I have.5

Latterly, my whole heart has been in rats;—white, old English black, & wild grey, which I have had Siamesed together in pairs, chiefly white & wild grey (for my stock of black is low) in a large number of cases—perhaps 30 or 40. pair.6 These have been fairly succesful operations so far as the well-beig & comfort of the animals is concerned but unexpected, out-of-the way accidents, are continually occurring. One pair died after 63 (about) days of union and injection into the body of the one passed into the other.

I hope in this way to test Pangenesis better than by the cross circulation for if even 1 drop of blood per hour passes from rat to rat, a volume equal to the entire contents of the circulation of either will be interchanged in 10 days & this is equal in its effects to a pretty complete intermingling of the bloods. All cristalloids diffuse readily from rat to rat (as poison) through the tissues, and as we know that eggs of entozoa are carried through the veins by the blood, it seems that a long continued Siamese union would be a valuable means of experiment.

We look forward with much pleasure on our return to town, to see your daughter in her new home.7 I do not think that I wrote myself, for my wife was writing, to offer you which I do now, my heartiest congratulations on the event.—8 But, you must miss her.

Ever sincerely your’s | Francis Galton


CD’s letter has not been found, but see the letter to Francis Galton, 14 April [1871].
Galton refers to CD’s holiday at Haredene, Albury, Surrey, from 28 July to 25 August (CD’s ‘Journal’ (Appendix II)). See letter from Emma Darwin to Roland Trimen, [22 August 1871].
Galton’s new assistant was probably Charles Henry Carter (see letter from Francis Galton, 21 November 1871); he replaced Oscar Louis Fraser, who left London for India in April 1871 (see Galton 1871, p. 305, and letter from Francis Galton to Francis Darwin, 7 April 1871 and n. 4).
The old English or black rat is Rattus rattus; the wild grey rat, more commonly known as the brown or Norway rat, is R. norvegicus. The common white rat is a colour morph of R. norvegicus.
Henrietta Emma Darwin married Richard Buckley Litchfield on 31 August 1871 (see CD’s ‘Journal’ (Appendix II)). The Litchfields lived at 2 Bryanston Street, Westminster, London (Post Office London directory 1872).
Louisa Jane Galton’s letter to the Darwins has not been found.


Galton, Francis. 1871. Experiments in pangenesis, by breeding from rabbits of a pure variety, into whose circulation blood taken from other varieties had previously been largely transfused. [Read 30 March 1871.] Proceedings of the Royal Society of London 19 (1870–1): 393–410.

Post Office London directory: Post-Office annual directory. … A list of the principal merchants, traders of eminence, &c. in the cities of London and Westminster, the borough of Southwark, and parts adjacent … general and special information relating to the Post Office. Post Office London directory. London: His Majesty’s Postmaster-General [and others]. 1802–1967.


Is turning to experiments with rats, "Siamesed together" for cross-circulation.

Letter details

Letter no.
Francis Galton
Charles Robert Darwin
Sent from
London, Rutland Gate, 42
Source of text
DAR 105: A33–4
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 7938,” accessed on 27 January 2022,

Also published in The Correspondence of Charles Darwin, vol. 19