WCP4390

[1]

Parkstone, Dorset.

August 29^th. 1892

My dear Poulton

I return your proof. I see nothing to object to in the article. I have not seen the book, but I read Beddard’s article on "Mimicry" in No.1 of "Natural Science", which is excessively weak & full of such fallacies as you expose.

As to panmixia you have quite misunderstood my position. By the "mean" condition, I do not mean the "mean" of ^during the whole course of development ^{of the organ,} as you seem to take it. That would indeed be [2] absurd. I do mean the "mean" of the whole series of ^individual variations now occurring, — during a period sufficient to contain all or almost all the variations to which the species is now subject. Take for instance such a case as the wings of the swallow, on the full development of which the life of the bird depends. Many individuals no doubt perish for lack of wing-powers, due to deficiency in size or form of wing, or in the muscles which move it. The extreme limits of variation would probably be seen if we could examine every swallow that had reached maturity during the last century. The average of all [3] these would perhaps be 5 or 10 per cent below the average of those that ^{survive to} become the parents of the next generation in any year; and what I maintain is, that panmixia alone could not reduce a swallow’s wings below the first average. Any further reduction must be due either to some form of selection, or to "economy of growth" — which is also, fundamentally, a form of selection. So with the eyes of cave animals, panmixia could only cause an imperfection of vision equal to the average of those variations which occurred, say, during a century before the animal entered the cave. It could only produce more effect than this [4]¹ if the effects of disuse are hereditary, which is a non-Weismannian doctrine. I think this is also the position that Romanes took.

Yours very truly| Alfred R. Wallace [signature]

P.S. I am very glad you liked my Polit[ical] art[icle] in 19^th Century.

A.R.W. [signature]