_Royal Gardens, Kew. August 2, 1880._

My dear Wallace,--I think you have made an immense advance to our
knowledge of the ways and means of distribution, and bridged many great
gaps.[14] Your reasoning seems to me to be sound throughout, though I am
not prepared to receive it in all its details.

I am disposed to regard the Western Australian flora as the latest in
point of origin, and I hope to prove it by development, and by the
absence of various types. If Western Australia ever had an old flora, I
am inclined to suppose that it has been destroyed by the invasion of
Eastern types after the union with East Australia. My idea is that these
types worked round by the south, and altered rapidly as they proceeded
westward, increasing in species. Nor can I conceive the Western Island,
when surrounded by sea, harbouring a flora like its present one.

I have been disposed to regard New Caledonia and the New Hebrides as the
parent country of many New Zealand and Australian forms of vegetation,
but we do not know enough of the vegetation of the former to warrant the
conclusion; and after all it would be but a slight modification of your
views.

I very much like your whole working of the problem of the isolation and
connection of New Zealand and Australia _inter se_ and with the
countries north of them, and the whole treatment of that respecting
north and south migration over the globe is admirable....--Ever most
truly yours,

J.D. HOOKER.