To John Jenner Weir 27 February 
Down. | Bromley. | Kent. S.E.
My dear Sir
I must thank you for yr paper on Apterous Lepidopt: which has interested me exceedingly, & likewise for the very honourable mention which you make of my name.1 It is almost a pity that yr paper was not published in some journal in which it wd have had a wider distribution. It contained much that was new to me. I think the part about the relation of the wings & spiracles & trachæ might have been made a little clearer.2 Incidentally you have done me a good service by reminding me of the rudimentary spurs on the legs of the partridge;3 for I am now writing on what I have called sexual selection. I believe that I am not mistaken in thinking that you have attended much to birds in confinement, as well as to insects. If you cd call to mind any facts bearing on this subject with Birds, insects or any animals—such as the selection by a female of any particular male—or conversely of a particular female by a male—or on the rivalry between males—or on the allurement of the females by the males—or any such facts, I shd be most grate〈ful〉 for the information if you wd have the kindness to communicate it.
Pray believe me— | my dear Sir | yours very faithfully | Ch. Darwin
P.S. I may give an instance of class of facts, that Barrow asserts, that a male Emberiza(?) at the Cape has immensely long tail-feathers during breeding season; & that if these are cut off, he has no chance of getting a wife.4 I have always felt an intense wish to make analogous trials, but have never had an opportunity, & it is not likely that you or anyone would be willing to try so troublesome an experiment. Colouring or staining the fine red breast of a bull-finch, with some innocuous matter into a dingy tint wd be an analogous case, & then putting him & ordinary males with a female.
A friend promised, but failed, to try a converse experiment with white pigeons, viz to stain their tails & wings with magenta or other colours & then observe what effect such a prodigious alteration would have on their courtship.5 It wd be a fine trial to cut off the eyes of the tail-feathers of male-peacocks, but who wd sacrifice the beauty of their bird for which reason to please a mere naturalist!
Thanks JJW for his paper on apterous insects [see 5939], which contained much new information.
Asks JJW for any information he may have on sexual selection.
Describes an experiment, still untried, of staining tail-feathers of male pigeons in bright colours to find the effect on courtship.
Please cite as
Darwin Correspondence Project, “Letter no. 5942,” accessed on 5 December 2016, http://www.darwinproject.ac.uk/DCP-LETT-5942