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See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1869

→ the difficulties 1872
difficulties are removed on the view here given 1859 1860 1861
difficulties 1866 1869
→ identical and allied 1869 1872
allied 1859 1860 1861 1866
→ now live so widely separated 1869 1872
live 1859 1860 1861 1866
→ south, and sometimes 1869 1872
southern temperate zones and 1859 1860 1861
southern tem- perate zones and 1866
→ intermediate mountain-ranges, are removed on the views above given. 1869 1872
mountains of the intertropical regions. 1859 1860 1861
mountains of the intertropical regions, are removed on the views above given. 1866
↑ 3 blocks not present in 1859 1860 1861 1869 1872; present in 1866
It is extremely difficult to understand how a vast number of peculiar forms confined to the tropics could have been therein preserved during the coldest part of the Glacial period. The number of forms in Australia, which are related to European temperate forms, but which differ so greatly that it is impossible to believe that they could have been modified since the Glacial period, perhaps indicates some much more ancient cold period, even as far back as the miocene age, in accordance with the recent speculations of certain geologists. So again, as I am informed by Mr. Bates, the strongly marked character of several species of Carabus, inhabiting the southern parts of America, indicates that their common progenitor must have been introduced at some early period; and other analogous facts could be given.
→ OMIT 1869 1872
during the recent Glacial period 1866
→ >We cannot say 1872
nor the reason 1866
OMIT 1869
→ forms, whilst 1872
OMIT 1869
groups of forms, and 1866
↑ 1 blocks not present in 1866 1869 1872; present in 1859 1860 1861
Very many difficulties remain to be solved.
→ The existence 1872
But the existence of several quite distinct species, belonging to genera exclusively confined to the south, 1859 1860 1861 1866
The existence, 1869
→ of species, which, though distinct, belong to genera exclusively confined to the south, is a 1869 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
→ OMIT 1869 1872
peculiar and very 1859 1860 1861 1866
→ belonging to the same genera have 1869 1872
have 1859 1860 1861 1866
→ It may be 1869 1872
I 1859 1860 1861 1866
→ had been already 1869 1872
were 1859 1860 1861 1866
The same principles apply to the distribution of terrestrial animals and of marine productions, in the northern and southern temperate zones, and on the intertropical mountains.
When
When,
during the height of the Glacial
period
period,
the ocean-currents were widely different to what they now are, some of the inhabitants of the temperate seas might have reached the equator; of these a few would perhaps at once be able to migrate southward, by keeping to the cooler currents, whilst others might remain and survive in the
cooler
colder
depths,
depths
until the southern hemisphere was in its turn subjected to a glacial climate and permitted
of
....
their further progress; in nearly the same manner as, according to Forbes, isolated spaces inhabited by Arctic productions exist to the present day in the deeper parts of the
temperate
northern temperate
seas.
I am
very far
far
from supposing that all →the difficulties in regard to the
range
distribution
and affinities of the →identical and allied
species
species,
which →now live so widely separated in the
northern
north
and →south, and sometimes on the →intermediate mountain-ranges, are removed on the views above given. ↑ The exact lines
and means
....
of migration →OMIT cannot be
indicated;
indicated.
→>We cannot say
why
why
certain
certain
species
species
and
and
not
not
others
others
have
have
migrated;
migrated;
why
why
certain
certain
species
species
have
have
been
been
modified
modified
and
and
have
have
given
given
rise
rise
to
to
new
new
→forms, whilst
others
others
have
have
remained
remained
unaltered.
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
ranges
species ranges
twice or thrice as far, and is twice or thrice as common, as another species within their own homes.
Various special difficulties also remain to be
solved:
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. →The existence at these and other distant points of the southern hemisphere, →of species, which, though distinct, belong to genera exclusively confined to the south, is a more remarkable
case
case.
of
....
difficulty.
....
For
....
some
Some
of these species are so distinct, that we cannot suppose that there has been time since the commencement of the
Glacial
last Glacial
period for their
migration,
migration
and
for their
....
subsequent modification to the necessary degree. The facts seem to
me to
....
indicate that →OMIT distinct species →belonging to the same genera have migrated in radiating lines from
some
a
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
Glacial
last Glacial
period, when the
antarctic
Antarctic
lands, now covered with ice, supported a highly peculiar and isolated flora. →It may be
suspect
suspected
that before this flora was exterminated
by
during
the
Glacial
last Glacial
epoch, a few forms →had been already widely dispersed to