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Darwin Correspondence Project

To William Bernhard Tegetmeier   3 February [1861]

Down Bromley Kent

Feb. 3d.

My dear Sir

I am much obliged to you for telling me of your curious case.1 I have never met with anything parallel; that is supposing the organs of generation are perfect. Everyone knows of the effect of castration on Deers Horns.—2 And I have read somewhere of a Deer in a ship which without being emasculated failed to reproduce its Horns.3

I have also read of males of small birds, like Bull-finches (I forget what kind) which on the moult in menageries failed to reproduce the male plumage— This case comes near yours, but then it has been supposed that the male organs had failed in their action.— How are castrated Cocks in plumage? Their spurs are said to grow to enormous size.—

I am very glad you are going to breed from your Bird. If fertile it will add greatly to interest; & if the variety should be inherited it will be still more curious.—4

With many thanks to you for telling me of this curious case | Believe me | My dear Sir | Yours sincerely | C. Darwin


Tegetmeier’s letter has not been found. He exhibited the ‘curious case’ at a meeting of the Zoological Society of London on 26 March 1861 (see Proceedings of the Zoological Society of London (1861), p. 102). CD described the case in Variation 1: 253: Mr. Tegetmeier has recorded the remarkable case of a brown-breasted red Game-cock which, after assuming its perfect masculine plumage, became hen-feathered in the autumn of the following year; but he did not lose voice, spurs, strength, nor productiveness.
CD discussed the general phenomenon of the assumption of female secondary sexual characteristics by males as a result of castration in Variation 2: 51–2.
See Variation 2: 158.
Tegetmeier was successful in breeding from the cock. In Variation 2: 253, CD reported: ‘This bird has now retained the same character during five seasons, and has begot both hen-feathered and male-feathered offspring.’


Is obliged for WBT’s "curious case". Discusses the effects of castration on development.

Letter details

Letter no.
Charles Robert Darwin
William Bernhard Tegetmeier
Sent from
Source of text
Archives of the New York Botanical Garden (Charles Finney Cox collection)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 3055,” accessed on 20 July 2019,

Also published in The Correspondence of Charles Darwin, vol. 9