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Darwin Correspondence Project

From Lawson Tait   12 March [1875]1

7, Great Charles St. | Birmingham.

Mar 12

Dear Sir,

I have had previous occasion to correspond with you on subjects bearing on evolution, and there is one more little matter on which I should like your opinion.2 As one of your disciples it has been my object to try the doctrine of evolution by survival of fitness at every possible point and amongst other things I have speculated on the origin of tails

For every tail I got a satisfactory reason, save for the bushy tail of such animals as the civet cat,3 some dogs, wolf &c. That variety long puzzled me until the accidental observation of a favourite white cat, who is perfectly deaf, solved the riddle to me On him I can perform experiments by reason of his deafness, without arousing his suspicion and I find that he uses his tail as a respirator to keep up his temperature. I catch him asleep before a German stove, lying at full length on his side with tail & limbs stretched out to enjoy the full heat. Then I intercept the heat by a screen & without waking he gradually coils himself up so as to cover as much surface as possible to save loss of heat. Then when I drive a current of cold air on him from a pair of bellows he twines his tail round him & buries his nose completely in the fur between it & the thigh, thereby establishing a natural respirator which must conserve his temperature to a very marked extent

Birds do the same thing when they bury their noses in their wings. I cannot find a bushy tailed animal which cannot curl itself up. If I could my theory would be spoilt

I mentioned this to my friend Prof Haughton4 of Dublin a few days ago when on a visit to him, and on a very cold morning we started round the Zoological Gardens to examine for the point. We found the civet cat & others coiled up & their noses covered with the fur. I do not know whether the observation is an original one or not, but it is at any rate interesting   I purpose communicating a short note on it to the Birmingham Natural History Society and previous to that I should like to know your opinion of my theory.5

Yours faithfully | Lawson Tait

CD annotations

Top of letter: ‘30£’ pencil


The year is established by Tait’s reference to his communication to the Birmingham Natural History Society (see n. 5, below).
The only earlier extant correspondence with Tait is the letter to Lawson Tait, 8 October 1871 (Correspondence vol. 19); it concerns the supra-condyloid foramen of the humerus.
The civet cat is Civettictis civetta, the African civet; it is not a cat, but a member of the family Viverridae.
Samuel Haughton.
Tait lectured on the subject of animals’ tails at the Birmingham Natural History Society on 5 April 1875; a summary of his remarks, including part of CD’s response to this letter, appeared in the Birmingham Daily Post, 8 April 1875, p. 6, and later in Hardwicke’s Science-Gossip, June 1875 (Tait 1875a). See letter to Lawson Tait, [13–15 March 1875].


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


Purpose of bushy tails; their usefulness to their owners as a means of keeping warm.

Letter details

Letter no.
Robert Lawson (Lawson) Tait
Charles Robert Darwin
Sent from
Source of text
DAR 178: 2
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9885,” accessed on 21 January 2022,

Also published in The Correspondence of Charles Darwin, vol. 23