he people who still insist
on former continents where now are deep oceans have ever dealt with the
almost physical impossibility of such a change having occurred without
breaking the continuity of terrestrial life, owing to the mean depth of
the ocean being at least six times the mean height of the land, and its
area nearly three times, so that the whole mass of the land of the
existing continents would be required to build up even _one small_
continent in the depths of the Atlantic or Pacific! I have demonstrated
this, with a diagram, in my "Darwinism" (Chap, XII.), and it has never
been either refuted or noticed, but passed by as if it did not exist!
Your whole discussion of Dispersal and Distribution is also admirable,
and I was much interested with your quotations from Guppy, whose book I
have not seen, but must read.

Most valuable to me also are your numerous references to Darwin's
letters, so that the article serves as a compendious index to the five
volumes, as regards this subject.

Especially admirable is the way in which you have always kept Darwin
before us as the centre of the whole discussion, while at the same time
fairly stating the sometimes adverse views of those who differ from him
on certain points....--Yours very truly,

ALFRED R. WALLACE.

* * * * *

SIR W.T. THISELTON-DYER TO A.R. WALLACE

_The Ferns, Witcombe, Gloucester. June 25, 1909._

Dear Dr. Wallace,--It is difficult for me to tell you how gratified I am
by your extraordinarily kind letter.... The truth is that success was
easy. It has been my immense good fortune to know most of those who
played in the drama. The story simply wanted a straightforward
amanuensis to tell itself. But it is a real pleasure to me to know that
I have met with some measure of success.

There are many essays in the book that you will not like any more than I
do. The secret of this lies in the fact, which you pointed out in your
memorable speech at the Linnean Celebration, that no one but a
naturalist can really understand Darwin.

I did not go to Cambridge--I had my hands full here. I was not sorry for
the excuse. There seemed to me a note of insincerity about the whole
business. I am short-tempered. I cannot stand being told that the origin
of species has still to be discovered, and that specific differences
have no "reality" (Bateson's Essay, p. 89). People are of course at
liberty to hold such opinions, but decency mi