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Darwin Correspondence Project

To Henry Doubleday   1 March [1868]1

Down. | Bromley. | Kent. S.E.

March 1.

My dear Sir

Mr Stainton has sent me a copy of your letter to him on the numerical proportions of the sexes of Insects,2 which has interested me greatly, & I venture to ask a few more questions, for the chance,—& I know it is an improbable chance—that you who have observed so acutely can throw any light on certain points.

Have you ever observed any marked difference in the numbers of the sexes during different years,—the males one season being in excess & the females during another, or conversely.—

Mr Stainton is very positive that he breeds many more females than males;3 but Dr Wallace of Colchester thinks this may arise from the larger & finer caterpillars striking the eye & being naturally chosen, & these would be the most likely to produce females.—4 What do you think of this?

Can you throw any light on the courtship of Butterflies: I think I have seen several males pursuing one female; now does the female favour one, or does the strongest male drive away the others; or is it, as Dr Wallace maintains, simple chance.—5 I fear no one can say.— I imagine that the beauty of the male in the case of species which are gaily coloured, & perhaps especially with those in which the sexes differ in colour, might determine the choice of female. Have you ever noticed anything leading you to suppose that Butterflies notice bright colours? I shd be most grateful for any hints or remarks, & I hope that you will excuse me for troubling you.

Perhaps you will remember having kindly sent me living specimens of Primula elatior; at last I have found time to draw up for Linn. Soc. an account of some observations on their powers of reproduction. It is as good a species as any in the world.— I will send you a copy of my paper whenever it is published.—6

Pray believe me | My Dear Sir | Yours very faithfully | Charles Darwin

My address for next 10 days will be 6. Queen Anne St. | Cavendish Sqr | London W.7


The year is established by the relationship between this letter and the letter from H. T. Stainton, 29 February 1868.
Henry Tibbats Stainton had enclosed a copy of a letter from Doubleday with his letter of 29 February 1868.
Alexander Wallace had written two letters to CD discussing sex ratios in silk moths, but he had not argued that a collector would be more likely to choose female caterpillars (see letters from Alexander Wallace, 25 February 1868 and 28 February 1868). In a letter of 14 March 1868, Wallace corrected CD on this point.
In his letter of 25 February 1868, Wallace had described female moths of Bombyx cynthia (now Samia cynthia) as passive and receptive to the first male that appeared.
Doubleday had first called CD’s attention to the existence of a form of oxlip (Primula elatior, the Bardfield oxlip) distinct from the common oxlip in 1860, and had supplied him with seedlings (see Correspondence vol. 8, letter from Henry Doubleday, 3 May 1860, and ‘Specific difference in Primula, p. 449). CD’s crossing experiments established that P. elatior was a distinct species and not a hybrid form. CD’s paper, ‘Specific difference in Primula, was read on 19 March 1868, and published in the 23 June 1868 issue of the Journal of the Linnean Society (Botany).
CD arrived at the house of his brother, Erasmus Alvey Darwin, on 3 March 1868, then stayed at Sarah Elizabeth Wedgwood’s house at 4 Chester Place, London, from 11 March, returning home on 1 April (see ‘Journal’ (Correspondence vol. 16, Appendix II)).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

‘Specific difference in Primula’: On the specific difference between Primula veris, Brit. Fl. (var. officinalis of Linn.), P. vulgaris, Brit. Fl. (var. acaulis, Linn.), and P. elatior, Jacq.; and on the hybrid nature of the common oxlip. With supplementary remarks on naturally produced hybrids in the genus Verbascum. By Charles Darwin. [Read 19 March 1868.] Journal of the Linnean Society (Botany) 10 (1869): 437–54.


Has been interested in copy of HD’s letter to H. T. Stainton on numerical proportions of the sexes of insects. Do they vary during different years?

Does he have opinions about the courtships of butterflies?

Will send a copy of his paper on Primula when it is published. [See 5997.]

Letter details

Letter no.
Charles Robert Darwin
Henry Doubleday
Sent from
Source of text
George W. Platzman (private collection)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5966A,” accessed on 21 October 2021,

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