hat the same genera
which have very variable species in Europe have other very variable
species elsewhere. This seems the general rule, but with some few
exceptions. I see from the several reasons which you assign, that there
is no hope of comparing the same genus at two different periods, and
seeing whether the tendency to vary is greater at one period in such
genus than at another period. The variability of certain genera or
groups of species strikes me as a very odd fact. (565/1. The late Dr.
Neumayr has dealt, to some extent, with this subject in "Die Stamme des
Thierreichs," Volume I., Wien, 1889.)

I shall have no points, as far as I can remember, to suggest for your
reconsideration, but only some on which I shall have to beg for a little
further information. However, I feel inclined very much to dispute your
doctrine of islands being generally ancient in comparison, I presume,
with continents. I imagine you think that islands are generally remnants
of old continents, a doctrine which I feel strongly disposed to doubt. I
believe them generally rising points; you, it seems, think them sinking
points.

LETTER 566. TO T.H. HUXLEY. Down, April 14th [1860].

Many thanks for your kind and pleasant letter. I have been much
interested by "Deep-sea Soundings,", and will return it by this post, or
as soon as I have copied a few sentences. (566/1. Specimens of the mud
dredged by H.M.S. "Cyclops" were sent to Huxley for examination, who
gave a brief account of them in Appendix A of Capt. Dayman's Report,
1858, under the title "Deep-sea Soundings in the North Atlantic.")
I think you said that some one was investigating the soundings. I
earnestly hope that you will ask the some one to carefully observe
whether any considerable number of the calcareous organisms are more or
less friable, or corroded, or scaling; so that one might form some crude
notion whether the deposition is so rapid that the foraminifera are
preserved from decay and thus are forming strata at this profound depth.
This is a subject which seems to me to have been much neglected in
examining soundings.

Bronn has sent me two copies of his Morphologische Studien uber die
Gestaltungsgesetze." (H.G. Bronn, "Morphologische Studien uber die
Gestaltungsgesetze der Naturkorper uberhaupt und der organischen
insbesondere": Leipzig, 1858.) It looks elementary. If you will write
you shall have the copy; if not I will give it to the Linnean Library.

I quite agree