I am so much pleased about the male musk Callichroma; for by odd chance I told Frank a week ago that next spring he must collect at Cambridge lots of Cerambyx moschatus, for as sure as life he would find the odour sexual!
You will be pleased to hear that I am undergoing severe distress about protection and sexual selection: this morning I oscillated with joy towards you; this evening I have [pg 223]swung back to the old position, out of which I fear I shall never get.
I did most thoroughly enjoy my talk with you three gentlemen, and especially with you, and to my great surprise it has not knocked me up. Pray give my kindest remembrances to Mrs. Wallace, and if my wife were at home she would cordially join in this.—Yours very sincerely,
CH. DARWIN.
I have had this morning a capital letter from Walsh of Illinois; but details too long to give.
Among Wallace's papers was found the following draft of a letter of his to Darwin:
9 St. Mark's Crescent, N.W. September 18, 1868.
Dear Darwin,—The more I think of your views as to the colours of females, the more difficulty I find in accepting them, and as you are now working at the subject I hope it will not interrupt you to hear "counsel on the other side."
I have a "general" and a "special" argument to submit.
1. Female birds and insects are generally exposed to more danger than the male, and in the case of insects their existence is necessary for a longer period.