this 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 if
the effects of disuse are hereditary--which is a non-Weismannian
doctrine. I think this is also the position that Romanes took.--Yours
faithfully,

A.R. WALLACE.

* * * * *

TO MR. J.W. MARSHALL

_Parkstone, Dorset. September 23, 1892._

My dear Marshall,--I am glad you enjoyed Mr. Hudson's book. His
observations are inimitable--and his theories and suggestions, if not
always the best, at least show thought on what he has observed.

I was most pleased with his demonstration as to the supposed instincts
of young birds and lambs, showing clearly that the former at all events
are not due to inherited experience, as Darwin thought. The whole book,
too, is pervaded by such a true love of nature and such a perception of
its marvels and mysteries as to be unique in my experience. The modern
scientific morphologists seem so wholly occupied in tracing out the
mechanism of organisms that they hardly seem to appreciate the
overwhelming marvel of the powers of life, which result in such
infinitely varied structures and such strange habits and so-called
instincts. The older I grow the more marvellous seem to me the mere
variety of form and habit in plants and animals, and the unerring
certitude with which from a minute germ the whole complex organism is
built up, true to the type of its kind in all the infinitude of details!
It is this which gives such a charm to the watching of plants
growing, and of kittens so rapidly developing their senses and
habitudes!...--Yours very faithfully,

ALFRED R. WALLACE.

* * * * *

TO PROF. POULTON

_Parkstone, Dorset. February 1, 1893._

My dear Poulton,--Thanks for the separate copy of your great paper on
colours of larva, pupa, etc.[21] I have read your conclusions and looked
over some of the experiments, and think you have now pretty well settled
that question.

I am reading through the new volume of the Life of Darwin, and am struck
with the curious example his own case affords of non-heredity of
acquired v