cold periods.
This latter view seems to me as difficult and inadequate as mine does to
him.--A.R.W.

* * * * *

Wallace was in frequent correspondence with Professor Raphael Meldola,
the eminent chemist, a friend both of Darwin and of Wallace, a student
of Evolution, and a stout defender of Darwinism. I received from him
much help and advice in connection with this work, and had he lived
until its completion--he died, suddenly, in 1914--my indebtedness to him
would have been even greater.

The following letter to Meldola refers to a suggestion that the white
colour of the undersides of animals might have been developed by
selection through the _physical_ advantage gained from the protection of
the vital parts by a _lighter_ colour and therefore by a surface of less
radiative activity. The idea was that there would be less loss of animal
heat through such a white coating. We were at that time unaware of
Thayer's demonstration of the value of such colouring for the purposes
of concealment among environment. Wallace accepted Thayer's view at once
when it was subsequently put forward; as do most naturalists at the
present time.

TO PROF. MELDOLA

_Frith Hill, Godalming. April 8, 1885._

My dear Meldola,--Your letter in _Nature_ last week "riz my dander," as
the Yankees say, and, for once in a way, we find ourselves deadly
enemies prepared for mortal combat, armed with steel (pens) and prepared
to shed any amount of our own--ink. Consequently I rushed into the fray
with a letter to _Nature_ intended to show that you are as wrong (as
wicked) as are the Russians in Afghanistan. Having, however, the most
perfect confidence that the battle will soon be over,... --Yours very
faithfully,

ALFRED R. WALLACE.

* * * * *

The following letter refers to the theory of physiological selection
which had recently been propounded by Romanes, and which Prof. Meldola
had criticised in _Nature_, xxxix. 384.

TO PROF. MELDOLA

_Frith Hill, Godalming. August 28, 1886._

My dear Meldola,--I have just read your reply to Romanes in _Nature_,
and so far as your view goes I agree, but it does not go far enough.
Professor Newton has called my attention to a passage in Belt's
"Nicaragua," pp. 207-8, in which he puts forth very clearly exactly your
view. I find I had noted the explanation as insufficient, and I hear
that in Darwin's copy there is "No! No!" against it. It