in MS. worked out the succession of
types in the Old World (as I remember telling Sedgwick, who of course
disbelieved it).

Since receiving your last letter on Hooker, I have read his introduction
as far as page xxiv (87/4. "On the Flora of Australia, etc.; being an
Introductory Essay to the Flora of Tasmania": London, 1859.), where
the Australian flora begins, and this latter part I liked most in
the proofs. It is a magnificent essay. I doubt slightly about some
assertions, or rather should have liked more facts--as, for instance, in
regard to species varying most on the confines of their range. Naturally
I doubt a little his remarks about divergence (87/5. "Variation is
effected by graduated changes; and the tendency of varieties, both in
nature and under cultivation, when further varying, is rather to depart
more and more widely from the original type than to revert to it." On
the margin Darwin wrote: "Without selection doubtful" (loc. cit., page
viii).), and about domestic races being produced under nature without
selection. It would take much to persuade me that a Pouter Pigeon, or
a Carrier, etc., could have been produced by the mere laws of variation
without long continued selection, though each little enlargement of crop
and beak are due to variation. I demur greatly to his comparison of the
products of sinking and rising islands (87/6. "I venture to anticipate
that a study of the vegetation of the islands with reference to
the peculiarities of the generic types on the one hand, and of the
geological conditions (whether as rising or sinking) on the other,
may, in the present state of our knowledge, advance other subjects of
distribution and variation considerably" (loc. cit., page xv).); in the
Indian Ocean he compares exclusively many rising volcanic and sinking
coral islands. The latter have a most peculiar soil, and are excessively
small in area, and are tenanted by very few species; moreover, such low
coral islands have probably been often, during their subsidence, utterly
submerged, and restocked by plants from other islands. In the Pacific
Ocean the floras of all the best cases are unknown. The comparison ought
to have been exclusively between rising and fringed volcanic islands,
and sinking and encircled volcanic islands. I have read Naudin (87/7.
Naudin, "Revue Horticole," 1852?.), and Hooker agrees that he does not
even touch on my views.

LETTER 88. J.D. HOOKER TO CHARLES DARWIN. [1859 or 1860.]