Alfred Russel Wallace 



History generalisation, etc., for another work, as if I wait 

 to incorporate all, I may wait for years. — Hoping you are 

 quite well, believe me yours very faithfully, 



Alfred R. Wallace. 



Down, Bromley, Kent, S.E. February 22, [1868 ?]. 



My dear Wallace, — I am hard at work on sexual selec- 

 tion and am driven half mad by the number of collateral 

 points which require investigation, such as the relative 

 numbers of the two sexes, and especially on polygamy. 

 Can you aid me with respect to birds which have strongly 

 marked secondary sexual characters, such as birds of para- 

 dise, humming-birds, the rupicola or rock-thrush, or any 

 other such cases ? Many gallinaceous birds certainly are 

 polygamous. I suppose that birds may be known not to 

 be polygamous if they are seen during the whole breeding 

 season to associate in pairs, or if the male incubates, or 

 aids in feeding the young. Will you have the kindness to 

 turn this in your mind ? but it is a shame to trouble you 

 now that, as I am heartily glad to hear, you are at work 

 on your Malayan Travels. I am fearfully puzzled how far 

 to extend your protective views with respect to the females 

 in various classes. The more I work, the more important 

 sexual selection apparently comes out. 



Can butterflies be polygamous ? — i.e. will one male im- 

 pregnate more than one female ? 



Forgive me troubling you, and I daresay I shall have 

 to ask your forgiveness again, and believe me, my dear 

 Wallace, yours most sincerely, q^. Darwin. 



P.S. — Baker has had the kindness to set the Entomo- 

 logical Society discussing the relative numbers of the 

 sexes in insects, and has brought out some very curious 

 results. 



194 



