LETTER 14. TO J.D. HOOKER.
[November] 1844.

...What a curious, wonderful case is that of the Lycopodium! (14/1. Sir
J.D. Hooker wrote, November 8, 1844: "I am firmly convinced (but not
enough to print it) that L. Selago varies in Van Diemen's Land into L.
varium. Two more different SPECIES (as they have hitherto been thought),
per se cannot be conceived, but nowhere else do they vary into one another,
nor does Selago vary at all in England.")...I suppose you would hardly have
expected them to be more varying than a phanerogamic plant. I trust you
will work the case out, and, even if unsupported, publish it, for you can
surely do this with due caution. I have heard of some analogous facts,
though on the smallest scale, in certain insects being more variable in one
district than in another, and I think the same holds with some land-shells.
By a strange chance I had noted to ask you in this letter an analogous
question, with respect to genera, in lieu of individual species,--that is,
whether you know of any case of a genus with most of its species being
variable (say Rubus) in one continent, having another set of species in
another continent non-variable, or not in so marked a manner. Mr. Herbert
(14/2. No doubt Dean Herbert, the horticulturist. See "Life and Letters,"
I., page 343.) incidentally mentioned in a letter to me that the heaths at
the Cape of Good Hope were very variable, whilst in Europe they are (?) not
so; but then the species here are few in comparison, so that the case, even
if true, is not a good one. In some genera of insects the variability
appears to be common in distant parts of the world. In shells, I hope
hereafter to get much light on this question through fossils. If you can
help me, I should be very much obliged: indeed, all your letters are most
useful to me.

MONDAY:--Now for your first long letter, and to me quite as interesting as