Thanks for information [about sex ratios] received from bird-catchers.
"Can you form any theory about all the many cases which you have given me and others which have been published, of when one pair is killed, another soon appearing?"
Facts about gay-coloured caterpillars very satisfactory.
Comments on Pangenesis.
4 Chester Place | N.W.
(Excuse this paper)
My dear Sir
I hardly know which of your 3 last letters has interested me most.—
What splendid work I shall have hereafter in selecting & arranging all your facts. Your last letter is most curious all about the bird-catchers & interested us all.— I suppose that the male chaffinch in ``pegging'' approaches the captive singing-bird, from rivalry or jealousy— if I am wrong please tell me; otherwise I will assume so.—
Can you form any theory about all the many cases which you have given me & others which have been published, of when one of pair is killed, another soon appearing? Your fact about the bullfinches in your garden is most curious on this head. Are there everywhere many unpaired birds? What can the explanation be?—
In your penultimate letter you tell me about gay caterpillars, & the facts seem to me highly satisfactory, but you speak as if they were few.— Would it not save you labour if I were to forward this letter to Wallace, & ask him for its return?
Many thanks for very curious case of Pavo nigripennis— I am very glad to get additional evidence; I have sent your fact to be inserted, if not too late, in four foreign editions which are now printing
I am delighted to hear that you approve of my Book— I thought
every mortal man w
The fertility of hybrid-canaries w
Yours most truly obliged | C. Darwin
- f1 6059.f1The year is established by the relationship between this letter and the letter from J. J. Weir,  March 1868.
- f2 6059.f2See letters from J. J. Weir, 23 March 1868, 24 March 1868, and  March 1868.
- f3 6059.f3See letter from J. J. Weir,  March 1868 and n. 7.
- f4 6059.f4See letter from J. J. Weir, 23 March 1868.
- f5 6059.f5In a note dated 24 March 1868 (DAR 86: C18), CD wrote, `Gould believes strongly that males in excess is usual rule with Birds.— When the bird-catchers first catch nightingales for first fortnight all are males, so severe contest when ♀ first arrives.' Another note suggests that CD had met John Gould at the British Museum on 23 March 1868 (DAR 84.2: 209). In Descent 1: 259, CD mentioned the information on nightingales.
- f6 6059.f6See letter from J. J. Weir, 24 March 1868 and n. 1. The reference is to Alfred Russel Wallace.
- f7 6059.f7See letter from J. J. Weir, 23 March 1868 and n. 6. Weir's information was not added to three of the four foreign editions of Variation (Carus trans. 1868, Moulinié trans. 1868, Kovalevsky trans. 1868--9), but was added to the American edition (Variation US ed., 1: iii), and was later added to the second edition (Variation 2d ed., 1: 306).
- f8 6059.f8CD refers to Variation and to the chapter on pangenesis (Variation 2: 357--404). Wallace had expressed support for the theory in his letter of 24 February 1868.
- f9 6059.f9See letter from J. J. Weir, 23 March 1868 and n. 2.