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Darwin Correspondence Project

To George Gulliver   18 December [1855]

Down Bromley Kent

Dec 18th.

Dear Sir

I thank you sincerely for your extremely kind letter, & for all the great trouble you have taken in explaining to me (& it was very necessary) how to send the blood.—1 I send by this Post, blood of the Barb, short-faced Tumbler & Dragon, which latter is nearly as good as that of Carrier.— These are 3 very distinct breeds: unfortunately I have not one common blue chequered rock or dovecot pigeon; nor is one kept, within half a dozen miles of this place: if you could possibly get blood of this, I shd. think it would be very desirable, as a standard.

I shall soon have Spanish Runts & Turbits,2 & if your examination gives any hope of anything curious I would send examples of them, & of Fantails & Pouters, & then you would have blood of every main breed.— I shall be very curious to hear the result.— With respect to your very kind offer of sending me the Book edited by you;3 if you are quite sure you can spare a copy, I shd. be very glad of it, for the fact stated by you of the difference in the blood of congenerous animals seems to me very curious.

I am nearly sure that the Passenger Pigeon & Turtle dove have interbred, so that if blood of the former differs from the latter, it is eminently curious.—4 I have often observed that when one single character in a species differs in a marked & extraordinary degree from that of its congeners, this character is apt to be variable, especially if several individuals from different habitats are observed: I presume that you examined the blood of only single individuals in the cases enumerated by you, in which the blood presented very marked characters; but I shd. be glad to hear whether you noticed any unusual variability in the corpuscles in these particular species.—

I am almost sure I have read in Zoolog. Proceeding an account by you of the Blood of the different races of Dogs;5 & if I am right, I have certainly marked the passage, & shall meet with it again, when going over the Books read of late years.— Nevertheless I shd. be very much obliged if you would inform me, whether it has so happened that you have, since such publication, examined the blood of any other varieties or Breeds of Dogs or of any other domesticated animals.

I fear you will think me quite unreasonable, but I would ask whether it would not be worth while to look at the Blood of Bantams, Cochin-Chinas, Dorking or Game; ie, of 2 or 3 of the most strongly marked races or species. You will see that the kindness of your note has made me greedy in my enquiries.—6

Pray believe me, my dear Sir, with very sincere thanks, | Your’s truly obliged | Charles Darwin


Gulliver, a surgeon in the army and also associated with the Royal College of Surgeons, was a specialist on the microscopic examination and measurement of blood cells. He had tabulated comparative measurements of red blood cells in Gulliver 1840 and Gulliver ed. 1846, pp. 237–43. One of his most striking observations was that the size and shape of the red corpuscles were different in different animals and that these differences might serve as a distinguishing feature for taxonomists (see Gulliver ed. 1846, p. 218 n.). CD had previously noted in his Questions & experiments notebook, p. 4a (Notebooks): ‘Is form of globule of blood in allied species similar.— if not how is it in allied [interl] varieties’.
An entry in CD’s Account book (Down House MS) for January 1856 reads: ‘Baily extra for runts’.
The works of William Hewson (Gulliver ed. 1846). There is a copy in the Darwin Library–CUL.
In Gulliver 1840, p. 44, Gulliver compared the blood corpuscles of the passenger pigeon with many different species of the Columbidae and concluded that they were quite peculiar. They approximated in ‘long diameter’ to those of the turtle dove, but differed in the ‘short diameter’.
Gulliver 1841. CD’s copy of the article, now in the Darwin Library–CUL, was not annotated.
For Gulliver’s reply to CD’s inquiries, see Correspondence vol. 6, letter from George Gulliver, 20 January [1856].


Sends blood of pigeons for examination. Discusses variation of blood in related animals.

Would like copy of book edited by GG [The works of W. Hewson (1846)].

Suggests investigation of blood in varieties of domesticated animals.

Letter details

Letter no.
Charles Robert Darwin
George Gulliver
Sent from
Source of text
Houghton Library, Harvard University
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1796,” accessed on 19 February 2018,

Also published in The Correspondence of Charles Darwin, vol. 5