ALFRED R. WALLACE.
9 St. Mark's Crescent, N.W. June 23, 1869.
Dear Darwin,—Thank you very much for the copy of your fifth edition of the "Origin." I have not yet read all the additions, but those I have looked at seem very interesting, though somewhat brief, but I suppose you are afraid of its great and rapid growth.
A difficult sexual character seems to me the plumules or battledore scales on the wings of certain families and genera of butterflies, almost invariably changing in form with the species and genera in proportion to other changes, [pg 245]and always constant in each species yet confined to the males, and so small and mixed up with the other scales as to produce no effect on the colour or marking of the wings. How could sexual selection produce them?
Your correspondent Mr. Geach is now in England, and if you would like to see him I am sure he would be glad to meet you. He is staying with his brother (address Guildford), but often comes to town.
Hoping that you have quite recovered from your accident and that the great work is progressing, believe me, dear Darwin, yours very faithfully,
ALFRED R. WALLACE.
P.S.—You will perhaps be pleased to hear that German, French, and Danish translations of my "Malay Archipelago" are in progress.—A.R.W.