WCP3949

[1]

Frith Hill, Godalming

March 28th, 1888

My dear Murie¹

I am preparing a volume on "Darwinism" and I want a few facts to assist me in some of my special views. Can you tell me any thing about the muscles that elevate the ornamental plumes of many birds. I suppose those that erect the hackle or the cock or pheasant are present in all birds, — but are those that erect the breast plumes of the Paradise birds or the extraordinary plumed tubercle on the neck of the Umbrella bird, or the 2 white feathers of Semioptera wallacei also present or rudiments of them in other allied birds? I presume every feather on a birds body is erectile, & [2] must therefore have muscles to erect it. Do those muscles act in the skin merely out of which the feathers grow, or are they attached to the roots of the feathers themselves?

Again; am I right in supposing that the habit of erecting any particular set of feathers would have a tendency to cause those feathers to grow more rapidly than others — would direct the circulation & nervous energy to them?

My theory, as you know, is that Darwin's sexual selection, as regards choice of the ♀ producing plumes & colours — is all imaginary — I maintain [3] that it was the vigour & peculiar motions of the male birds at the breeding season, that first started the growth of the ornamental plumes. Their display, ^when formed, follows as a necessary consequence.

A few grains from your store of anatomical knowledge will oblige.

Yours faithfully | Alfred R. Wallace [signature]