Comparison with 1859 |
|
in the northern
and
southern temperate zones and southern temperate zones and 1859 1860 1861 |
southern tem- perate zones and 1866 |
south, and sometimes 1869 1872 |
on the
mountains of the intertropical regions. mountains of the intertropical regions. 1859 1860 1861 |
mountains of the intertropical regions, are removed on the views above given. 1866 |
intermediate mountain-ranges, are removed on the views above given. 1869 1872 |
↑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.
|
↑1 blocks not present in 1859 1860 1861; present in 1866 1869 1872 | The exact lines and means
of migration during the recent Glacial period
cannot be indicated;
nor the reason why certain species and not others have migrated; why certain species have been modified and have given rise to new nor the reason 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. others have remained unaltered.
|
Very many difficulties remain to be solved. I do not pretend to indicate the exact lines and means of migration, or the reason
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 man's
agency in a foreign land; why one
ranges ranges 1859 1860 1861 | species ranges 1866 1869 1872 |
twice or thrice as far, and is twice or thrice as common, as another species within their own homes. ↑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.
|
|
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 1859 1860 1861 | that, 1866 |
as far as regards the occurrence of identical species at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia, I believe
|
in the
northern northern 1859 1860 1861 1866 | north 1869 1872 |
and
southern tem- perate zones and southern tem- perate zones and 1866 |
southern temperate zones and 1859 1860 1861 |
south, and sometimes 1869 1872 |
on the
mountains of the intertropical regions, are removed on the views above given. mountains of the intertropical regions, are removed on the views above given. 1866 |
mountains of the intertropical regions. 1859 1860 1861 |
intermediate mountain-ranges, are removed on the views above given. 1869 1872 |
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. The exact lines
and means and means 1866 | and means 1869 1872 |
of migration
during the recent Glacial period during the recent Glacial period 1866 |
OMIT 1869 1872 |
cannot be
indicated; indicated; 1866 | indicated. 1869 1872 |
nor the reason nor the reason 1866 |
>We cannot say 1872 |
OMIT 1869 |
why
certain certain 1866 1872 | certain 1869 |
species species 1866 1872 | species 1869 |
and
not
others others 1866 1872 | others 1869 |
have
migrated; migrated; 1866 1872 | migrated; 1869 |
why
certain certain 1866 1872 | certain 1869 |
species species 1866 1872 | species 1869 |
have
been
modified modified 1866 1872 | modified 1869 |
and
have
given given 1866 1872 | given 1869 |
rise
to
new
groups of forms, and groups of forms, and 1866 |
OMIT 1869 |
forms, whilst 1872 |
others others 1866 1872 | others 1869 |
have
remained remained 1866 1872 | remained 1869 |
unaltered. unaltered. 1866 1872 | unaltered. 1869 |
↑1 blocks not present in 1866 1869 1872; present in 1859 1860 1861 | Very many difficulties remain to be solved.
|
We cannot hope to explain such facts, until we can say why one species and not another becomes naturalised by
man's man's 1859 1861 1866 1872 | mans 1860 1869 |
agency in a foreign land; why one
species ranges species ranges 1866 1869 1872 | ranges 1859 1860 1861 |
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, 1866 | that 1859 1860 1861 |
as far as regards the occurrence of identical species at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia, I believe
|