| → 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 |
|
|
why certain species and not others have migrated; 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
agency in a foreign land; why one
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
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
of these species are so distinct, that we cannot suppose that there has been time since the commencement of the
period for their
and
subsequent modification to the necessary degree. The facts seem to
indicate that
→peculiar and very
distinct species
→have
migrated in radiating lines from
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
period, when the
lands, now covered with ice, supported a highly peculiar
|
