To W. B. Tegetmeier   27 [December 1862]

Down Bromley Kent

27th

My dear Sir

I thank you sincerely for your letter,1 & am heartily glad to hear of R.S. making so good a move.2 I am, however, not sanguine of success.— The present plan is to try whether any existing breeds happen to have acquired accidentally any degree of sterility;—but to this point hereafter.3 The enclosed M.S. will show what I have done & know on the subject. Please at some future time carefully return the MS. to me.4 If I were going to try again, I would prefer Turbit with Carrier or Dragon.—

I will suggest an analogous experiment, which I have had for two years in my Experimental book with “be sure & try”.5 but which as my health gets yearly weaker & weaker & my other work increases, I suppose I shall never try. Permit me to add that if 5£ would cover expences of experiment, I shd. be delighted to give it & you could publish result if there be any result.6 I crossed Spanish Cock (your bird) & white Silk hen & got plenty of eggs & chickens; but two of these seemed to be quite sterile.7

I was then sadly overdone with work but have ever since much reproached myself, that I did not preserve & carefully test the procretive power of these hens.— Now if you are inclined to get a Spanish Cock & a couple of white Silk hens, I shall be most grateful to hear whether the offspring breed well; they will prove, I think, not hardy; if they shd. prove sterile,, which I can hardly believe, they will anyhow do for the pot.—

If you do try this; how would it be to put a silk cock to your curious silky Cochin Hen; so as to get a big Silk breed; it would be curious if you could get silky fowl with bright colours— I believe a silk hen crossed by any other breed never give silky feather. A cross from Silk Cock & Cochin Silk Hen ought to give silky feathers & probably bright colours.—

I have been led lately from experiments (not published) on Dimorphism to reflect much on sterility from Hybridism & partially to change the opinion given in Origin.8 I have now letters out enquiring on following point, implied in the experiment, which seems to me well-worth trying, but too laborious ever to be attempted.9 I would ask every Pigeon & Fowl Fancier, whether they have ever observed in the same breed, a cock A paired to a hen B, which did not produce young. Then I would get cock A & match it to a hen of its nearest blood; & hen B to its nearest blood. I would then match the offspring of A (viz a, b, c, d, e) to the offspring of B, (viz f, g, h, i, j)—& all these children which were fertile together should be destroyed until I found, one, (say a) which was not quite fertile with (say i). Then a & i shd. be preserved & paired with their parents A & B, so as to try & get two families, which would not unite together; but the members within each family being fertile together. This would probably be quite hopeless; but he who could effect this, would, I believe, solve the problem of Sterility from Hybridism.—

If you shd ever hear of individual fowls or pigeons which are sterile together, I shd. be very grateful to hear of case. It is parallel case to those recorded of a man not impotent long living with a woman who remained childless; the husband died & the woman married again & had plenty of children. Apparently (by no means certainly) this first man & woman were dissimilar in their sexual organisation.10 I conceive it possible that their offspring (if both had married again & both had children would be sexually dissimilar like their parents or sterile together.—

Pray forgive my dreadful writing; I have been very unwell all day, & have no strength to rewrite this scrawl.— I am working slowly on, & I suppose in 3 or 4 months shall be ready for M.S. of Fowls.11

My dear Sir | Yours very sincerely | C. Darwin

I am sure I do not know whether any human being could understand or read this shameful scrawl.—

Endorsement: ‘Decr. 1862.’

1
Tegetmeier’s letter has not been found, but see the letter to T. H. Huxley, 28 December [1862].
2
On 1 December 1862, the council of the Royal Society of London resolved to grant £10 to Tegetmeier for ‘experiments on the cross-breeding of pigeons’ (Royal Society, Council minutes, 1 December 1862). Between 1863 and 1865, Tegetmeier carried out a series of crosses between varieties of pigeon designed to test the fertility of their hybrids; he tested the products of three generations without finding ‘any trace of sterility’ (see letters from W. B. Tegetmeier, 7 July 1863 (Correspondence vol. 11) and 13 March 1865, Calendar no. 4785). CD reported Tegetmeier’s results in Variation 1: 192.
3
See n. 8, below.
4
The enclosure has not been found; it was evidently a list of the crosses between different pigeon varieties carried out by CD and others (see Correspondence vol. 11, letter to W. B. Tegetmeier, 19 February [1863]). The list is probably that referred to in Variation 1: 192 n., which CD did not think ‘worth publishing’. CD began keeping pigeons for experimental purposes in April 1855, and in August 1856 he began crossing all kinds, ‘to see whether crosses are fertile’ (see Correspondence vol. 5, letter to W. E. Darwin, [25 April 1855], and Correspondence vol. 6, letter to W. B. Tegetmeier, 30 August [1856]); the records of his crosses in 1856 and 1857 are in DAR 205.7: 166–89. See also CD’s Catalogue of Down specimens (Down House MS). Tegetmeier apparently did not return the list until 1865 (see letter to W. B. Tegetmeier, 6 March [1865], Calendar no. 4779, and letter from W. B Tegetmeier, 13 March 1865, Calendar no. 4785).
5
This reference has not been found in CD’s Experiment book (DAR 157a), but see n. 7, below.
6
CD sent £5 5s. to cover the cost of the experiments in his letter to Tegetmeier of 9 July [1863] (Correspondence vol. 11). Tegetmeier carried out the crosses between 1863 and 1865 (see letters from W. B. Tegetmeier, 7 July 1863 (Correspondence vol. 11) and 13 March 1865, Calendar no. 4785). He published an account of the experiments in Tegetmeier 1867, p. 224; CD reported Tegetmeier’s observations in Variation 1: 242.
7
The reference is to crossing experiments that CD carried out in 1859 and 1860 with a male Spanish fowl provided by Tegetmeier (see Correspondence vol. 7, letters to W. B. Tegetmeier, 16 November [1858], 27 [November 1858], and 24 December [1858]). By crossing different varieties, CD hoped to produce a reversion to the coloration of the presumed ancestral breed. The results from these experiments are given in his Experiment book (DAR 157a), pp. 41–2, 49–50, and in Variation 1: 240–2, 2: 67.
8
See Correspondence vol. 10, Appendix VI.
9
The letters referred to have not been found, but see Correspondence vol. 10, Appendix VI.
10
CD referred to this point in his notes on hybridity (see Correspondence vol. 10, Appendix VI).
11
In June 1861, CD had sent the manuscript of a draft chapter on domestic fowls, prepared for inclusion in Variation, for Tegetmeier’s comments (see Correspondence vol. 9, letter to W. B. Tegetmeier, 14 June [1861]). In the event, Tegetmeier did not read and return the manuscript with his comments until 1865 (see letter to W. B. Tegetmeier, [7 April 1865], Calendar no. 4806).

Manuscript Alterations and Comments

1.4 M.S.] after del ‘dreadfully rough’
1.5 on the] after del ‘(and long noted)’
1.5 the subject] ‘the’ interl
1.5 carefully] interl
1.6 with] above del ‘&’
2.2 as] over illeg
2.2 my health] after del ‘I’
3.1 with work] interl
3.2 power] above del ‘power’
3.4 breed] above del ‘breed’
3.5 not hardy] above del ‘tender’
4.1 it be] ‘it’ interl
4.1 silky] interl
4.4 Silk Hen] ‘Silk’ interl
5.2 the opinion] ‘the’ interl
5.7 cock] interl
5.7 to] interl
5.8 I would then match] above del ‘Of’
5.9 & all … which] above del ‘if these little letters’
5.9 children] after del ‘grand’
5.9 together should 5.10] above del ‘they shd all’
5.11 Then a & i] above del ‘These’
5.14 this,] interl
6.1 fowls] above del ‘fowles’
6.2 not impotent 6.3] interl
6.4 plenty of] interl
6.5 first] interl
6.6 (if both … children] interl
6.7 like their parents] interl
6.7 together] over ‘.—’
7.1 day,] comma altered from full stop
7.1 & have … scrawl.— 7.2] added

Please cite as “DCP-LETT-3877,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-3877