Progress of pigeon and poultry breeding experiments. No loss of fertility observed yet.
Blue-eyed cats and deafness.
Muswell Hill | London. N.
July 7— 63.
My dear Sir
I thought that you might like to hear some of the results of the experiments that I have been trying, respecting the fertility of Mongrels.
I have crossed three pair of Black Barbs and White Fantails, and am keeping the offspring for breeding next year.
The plumage has in all cases taken more after the male than the female parent.— In no case has there been any sign of want of fertility—
In accordance with your suggestion I have also experimented on the Silk fowl and Spanish Cross with A very good pure bred Spanish Cock and two rather old Silk fowl hens.— Only one of these laid. 9 eggs. They were left in the nest and she sat, producing 9 chicks, all black plumage, violet black skin.— Obviously identical with the Coq. Nˆegre of Temminck— None, even slightly, silky
I shall keep a cock and several pullets for breeding next season— Other fowls will breed for 5 or 6 seasons on end in breeding without a fresh cross, if these do not do the same it will be an indication of greater sterility in these mongrels than in pure breeds.
There were some paragraphs in the Field the other day respecting all blue-eyed cats not being deaf, as I think you have stated. If you have not seen the correspondence I will cut it out and forward it to you.
I forward you by this same post a number of the Intellectual Observer containing a short article of mine on Variation in Plumage at page 173—I have endeavoured to account for the circumstances that no small birds exist in a wild state with silky plumage but hardly expect that the idea has not occured to you.
Trusting to hear that you are in good health | Believe me | Yours faithfully | W B
C Darwin Esq
- f1 4233.f1Tegetmeier originally dated the letter `29 June. 1863', but subsequently altered the date to `July 7— 63.'; the most likely explanation is that he began writing the letter on the former date, but was interrupted, resuming on the latter date.
- f2 4233.f2At the end of 1862, CD had suggested that Tegetmeier attempt to establish by experiment whether any existing breeds of pigeon had acquired `accidentally any degree of sterility'; he also suggested a similar experiment with fowls (see Correspondence vol. 10, letter to W. B. Tegetmeier, 27 [December 1862]). See also letters to W. B. Tegetmeier, 26 [January 1863] and 19 February , and letters from W. B. Tegetmeier, [after 26 January 1863] and 18 February 1863.
- f3 4233.f3Tegetmeier continued his experiments through two further breeding seasons (see letters from W. B. Tegetmeier, [before 21 December 1864] (Correspondence vol. 12) and 13 March 1865 (Calendar no. 4785)). CD reported Tegetmeier's findings with respect to the fertility inter se of different domestic varieties of pigeon in Variation 1: 192.
- f4 4233.f4See Correspondence vol. 10, letter to W. B. Tegetmeier, 27 [December 1862].
- f5 4233.f5Temminck 1813--15, 2: 253--5. See also Tegetmeier 1863b, p. 172.
- f6 4233.f6Tegetmeier published an account of these experiments in Tegetmeier 1867, p. 224; there is an annotated copy of this work in the Darwin Library--CUL (see Marginalia 1: 800--3). CD reported Tegetmeier's observations in Variation 1: 242.
- f7 4233.f7The reference is to Origin, p. 12, in which CD wrote: `cats with blue eyes are invariably deaf'; see also Origin, p. 144. A series of letters disputing this assertion appeared in the Field 21 (1863): 416, 439, 524, and 547. In the third edition of Origin, CD altered the statement to read: `cats with blue eyes are generally deaf' (Origin 3d ed., p. 12); in the fourth edition, published in 1866, he altered it again to read: `cats which are entirely white and have blue eyes are generally deaf' (Origin 4th ed., p. 12). In discussing this phenomenon in Variation 2: 329, CD observed: `I formerly thought that the rule was invariable, but I have heard of a few authentic exceptions'; however, the counter-examples cited are not those referred to here.
- f8 4233.f8Tegetmeier 1863b appeared in the April 1863 number of the Intellectual Observer. In his article, Tegetmeier demonstrated how a silky variety of fowl could be established by artificial selection from a naturally occurring variation. He then argued that no breed of small, silky fowl could survive in a state of nature, since this variation in plumage made fowls flightless, and it was `obvious that a bird of moderate size, destitute of any natural means of defence, and incapable of escape by flight, could scarcely … avoid being destroyed by its natural carnivorous enemies' (ibid., p. 173).