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Darwin Correspondence Project

From J. V. Carus   20 November 1871


Nov. 20. 1871.

My dear Sir,

The breeder of our oldest herd of Merino sheep (bred a hundred years without introducing foreign blood)1 writes me, that “after the castration of the male lambs, which takes place about 6 weeks after the birth, the development of the horns is checked, the castrated rams have horns, but always smaller and feebly developed ones.”

The second breeder writes: “My herd is an original one, descended also directly through the female line from the spanish sheep introduced within the last quarter of past century (Merino).— Castrated male animals have horns, which are developed in much smaller dimensions, about of the size of the horns of the female sheep. If the castration is effected very early, the horns remain almost undeveloped.”2

I translate as litterally as possible. It seems partly to depend on the time of the castration. “Almost undeveloped” is pretty well the same as “rudimentary”. But it is only stated, when the castration has been made very early. For the general case seems to be, that the development of the horns is checked, that is horns are reduced in size.

Don’t trouble yourself with marking the corrected passages. Send the proofs as they are.3

Many thanks for your kind information about the goat-sheep (as C. Vogt calls them). The quotation of Chevreul is quite right: Botanique. It is a paper on species, varieties, races.” He refers to a a communication (as it seems an oral one) from Mr Gay.4

With my best wishes I am | My dear Sir | Yours most sincerely | J. Victor Carus

CD annotations

1.3 about 6 weeks after] underl pencil
4.1 Don’t … Gay. 5.4] crossed pencil


Robert Sison was the breeder at the Royal Farm in Lohmen, Saxony; his flock were descendants of the first merinos sent to Saxony in 1765 and 1775 from Spain (Sison 1867). See also Correspondence vol. 17, letter from J. V. Carus, 22 January 1869.
The second breeder has not been identified. CD had asked Carus about the effects of castration on the growth of horns in merino lambs (see letter to J. V. Carus, 17 November 1871 and n. 8). CD added information from Carus, quoting extracts from this letter, in Descent 2d ed., p. 527 and n. 18.
Carus had requested references on the breeding of hybrids from sheep and goats; such hybrids had been mentioned by Carl Vogt (see letter from J. V. Carus, 14 November 1871 and n. 3). For CD’s reply, see the letter to J. V. Carus, 17 November 1871 and n. 3.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Descent 2d ed.: The descent of man, and selection in relation to sex. By Charles Darwin. 2d edition. London: John Murray. 1874.

Sison, Robert. 1867. Lohmen. Königliche Merino Stammschäferei Sachsens v. 1765. Agronomische Zeitung 22: 209–12.


Horns of castrated merino rams remain almost undeveloped.

Letter details

Letter no.
Julius Victor Carus
Charles Robert Darwin
Sent from
Source of text
DAR 88: 117–118
Physical description
ALS 3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8077,” accessed on 21 June 2024,

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