See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1860
1861
1866
1869
1872

groups of forms, and 1859 1860 1861
forms, whilst 1869

1 blocks not present in 1859 1860 1861 1866; present in 1869 1872
Various special difficulties also remain to be solved: for instance, the occurrence, as shown by Dr. Hooker, of the same plants at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia; but icebergs, as suggested by Lyell, may have been concerned in their dispersal.

But the existence of several quite distinct species, belonging to genera exclusively confined to the south, 1859 1860 1861 1866
The existence, 1869
The existence 1872

is, on my theory of descent with modification, a far 1859 1860 1861
is, on the theory of descent with modification, a far 1866
of species, which, though distinct, belong to genera exclusively confined to the south, is a 1869 1872

peculiar and very 1859 1860 1861 1866
OMIT 1869 1872

have 1859 1860 1861 1866
belonging to the same genera have 1869 1872

I 1859 1860 1861 1866
It may be 1869 1872

were 1859 1860 1861 1866
had been already 1869 1872

why certain species have been modified and have given rise to new groups of forms, and others have remained unaltered. We cannot hope to explain such facts, until we can say why one species and not another becomes naturalised by
mans
man's
agency in a foreign land; why one
species ranges
ranges
twice or thrice as far, and is twice or thrice as common, as another species within their own homes.
I have said that many difficulties remain to be solved: some of the most remarkable are stated with admirable clearness by Dr. Hooker in his botanical works on the antarctic regions. These cannot be here discussed. I will only say
that,
that
as far as regards the occurrence of identical species at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia, I believe that towards the close of the Glacial period, icebergs, as suggested by Lyell, have been largely concerned in their dispersal. But the existence of several quite distinct species, belonging to genera exclusively confined to the south, at these and other distant points of the southern hemisphere, is, on my theory of descent with modification, a far more remarkable
case.
case
of
of
difficulty.
difficulty.
For
For
Some
some
of these species are so distinct, that we cannot suppose that there has been time since the commencement of the
last Glacial
Glacial
period for their
migration
migration,
and
for their
for their
subsequent modification to the necessary degree. The facts seem to
me to
me to
indicate that peculiar and very distinct species have migrated in radiating lines from
a
some
common centre; and I am inclined to look in the southern, as in the northern hemisphere, to a former and warmer period, before the commencement of the
last Glacial
Glacial
period, when the
Antarctic
antarctic
lands, now covered with ice, supported a highly peculiar and isolated flora. I
suspected
suspect
that before this flora was exterminated
during
by
the
last Glacial
Glacial
epoch, a few forms were