skip to content

Darwin Correspondence Project

To J. J. Weir   27 March [1868]1

4 Chester Place | N.W.

March 27

(Excuse this paper)

My dear Sir

I hardly know which of your 3 last letters has interested me most.—2

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.—3

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.4 Are there everywhere many unpaired birds? What can the explanation be?—

Mr. Gould assures me that all the nightingales which first come over are males, & he believes this is so with other migratory birds.—5 But this does not agree with what the bird-catchers say about the common Linnet, which I suppose migrates within the limits of England.—

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?6

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 printing7

I am delighted to hear that you approve of my Book— I thought every mortal man wd find the details very tedious & have often repented of giving so many.— You will find Pangenesis stiff reading & I fear will shake your head in disapproval: Wallace sticks up for the great god Pan like a man.—8

The fertility of hybrid-canaries wd. be a fine subject for careful investigation.9

Yours most truly obliged | C. Darwin


The year is established by the relationship between this letter and the letter from J. J. Weir, [26] March 1868.
See letters from J. J. Weir, 23 March 1868, 24 March 1868, and [26] March 1868.
In 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.
See letter from J. J. Weir, 24 March 1868 and n. 1. The reference is to Alfred Russel Wallace.
See 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).
CD 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.


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.

Letter details

Letter no.
Charles Robert Darwin
John Jenner Weir
Sent from
London, Chester Place, 4
Source of text
Linnean Society of London (Quentin Keynes Collection)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6059,” accessed on 17 June 2018,

Also published in The Correspondence of Charles Darwin, vol. 16