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Darwin Correspondence Project

From John Walton   [after 4 April 1866]1

– –

I remember hearing the late professor Dicks of Edinburgh2 say in a lecture at the Veternary college there that he once knew an instance of a fully developed tooth being found in the testicul of a horse that I thought a very singular place for a tooth to grow in perhaps the very last member of the body where one would have expected it.3

I have often remarked the great fleetness of hares in countries where greyhound coursing is much followed. I have lived in places where few or no greyhounds were kept and the hares though not more numerous were so slow that they were not unfrequently caught by the sheep dogs in a [fore] course while when tried with greyhounds they made no sport   but in countries where many greyhounds are kept where the landlord of each village public house has his coursing dog & where dogs are constantly being excercised and tried they do not catch one hare out of three they are sliped at so fleet do they get by being bred by natural selection from the strongest & fleetest sires & dams.4

I have now Sir jotted down the few things that come into my mind while I read your book   if they are of the least use to you as confirmatory evidence I shall be glad to think it a little return for the pleasure received by me from your writings

I am Sir | Your Obedient Servant | John Walton [jr]

CD annotations

1.1 I remember … it. 1.5] crossed pencil
2.1 I have] after opening square bracket, pencil; ‘Selection’5 pencil
3.1 I have now … writings 3.3] crossed pencil


The date is established by the reference to William Dick (see n. 2, below). The correspondent has not been further identified.
William Dick, professor at the Veterinary College, Edinburgh, died on 4 April 1866 (Modern English biography).
In Variation, CD briefly discussed cases in which teeth or hair appeared in unusual parts of the body, and in ovarian tumours; he argued that his theory of pangenesis could explain such abnormalities (see Variation 2: 369–70, 391–3).
CD remarked on the modifications of rabbits owing to use and disuse of parts of their bodies in Variation 1: 124–30, and discussed the specific effects of use and disuse in domestic and wild animals, including the importance of exercise in strengthening muscles, in Variation 2: 295–9. In Origin, pp. 90–1, CD had described how, in animals who prey on other animals in the wild, natural selection might preserve the swiftest, giving the example of wolves; he also compared wolves with greyhounds.
CD’s annotation may refer to the section of chapter 4 of Origin, ‘Illustrations of the action of natural selection’, pp. 90–6, or to his chapters on selection in Variation 2: 192–249. Walton’s example was not added to Variation or to later editions of Origin.


Reports of a tooth found in the testicle of a horse.

Hares are very fleet in countries in which greyhound coursing is developed, slow in those in which no greyhounds are kept.

Letter details

Letter no.
John Walton, Jr
Charles Robert Darwin
Sent from
Source of text
DAR 47: 210
Physical description
2pp inc †

Please cite as

Darwin Correspondence Project, “Letter no. 13851,” accessed on 18 February 2019,

Also published in The Correspondence of Charles Darwin, vol. 14