Down, Bromley, Kent, S.E.  April 30, 1868.

My dear Wallace,—­Your letter, like so many previous ones, has interested me much.  Dr. Allbutt’s view occurred to me some time ago, and I have written a short discussion on it.  It is, I think, a remarkable law, to which I have found no exception.  The foundation lies in the fact that in many cases the eggs or seeds require nourishment and protection by the mother-form for some time after impregnation.  Hence the spermatozoa and antherozoids travel in the lower aquatic animals and plants to the female, and pollen is borne to the female organ.  As organisms rise in the scale it seems natural that the male should carry the spermatozoa to the females in his own body.  As the male is the searcher he has received and gained more eager passions than the female; and, very differently from you, I look at this as one great difficulty in believing that the males select the more attractive females; as far as I can discover they are always ready to seize on any female, and sometimes on many females.  Nothing would please me more than to find evidence of males selecting the more attractive females [? in pigeons[69]]:  I have for months been trying to persuade myself of this.  There is the case of man in favour of this belief, and I know in hybrid [lizards’[69]] unions of males preferring particular females, but alas! not guided by colour.  Perhaps I may get more evidence as I wade through my twenty years’ mass of notes.

I am not shaken about the female protected butterflies:  I will grant (only for argument) that the life of the male is of very little value; I will grant that the males do not vary; yet why has not the protective beauty of the female been transferred by inheritance to the male?  The beauty would be a gain to the male, as far as we can see, as a protection; and I cannot believe that it would be repulsive to the female as she became beautiful.  But we shall never convince each other.  I sometimes marvel how truth progresses, so difficult is it for one man to convince another unless his mind is vacant.  Nevertheless, I myself to a certain extent contradict my own remark; for I believe far more in the importance of protection than I did before reading your articles.

I do not think you lay nearly stress enough in your articles on what you admit in your letter, viz. “there seems to be some production of vividness ... of colour in the male independent of protection.”  This I am making a chief point; and have come to your conclusion so far that I believe that intense colouring in the female sex is often checked by being dangerous.