Comparison with 1872 |
|
During the periods of subsidence
there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be
less less 1872 | least 1859 1860 1861 1866 1869 |
perfect. |
|
It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would
exceed the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not fully
preserved, transitional varieties would merely appear as so many
new, though closely allied new, though closely allied 1872 |
distinct 1859 1860 1861 1866 |
new and distinct 1869 |
species. It is,
also,
probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would have to
migrate, and no closely consecutive record of their modifications could be preserved in any one formation. |
|
Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy leads me to
believe
that it would be chiefly these far-ranging species
which
would oftenest produce new varieties; and the varieties would at first
....... 1872 | generally 1859 1860 1861 1866 1869 |
be local or confined to one place, but if possessed of any decided advantage, or when further modified and improved, they would slowly spread and supplant their parent-forms. When such varieties returned to their ancient homes, as they would differ from their former
state state 1872 | state, 1859 1860 1861 1866 1869 |
in
|
During the periods of
subsidence, subsidence, 1861 1866 1869 1872 | subsidence 1859 1860 |
there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be
least least 1859 1860 1861 1866 1869 | less 1872 |
perfect. |
|
It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would
exceed
exceed
1859 1860 1866 1869 1872 | exceed 1861 |
the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not
all fully all fully 1861 1866 1869 1872 | fully 1859 1860 |
preserved, transitional varieties would merely appear as so many
distinct distinct 1859 1860 1861 1866 |
new and distinct 1869 |
new, though closely allied 1872 |
species. It
is is 1861 1866 1869 1872 | is, 1859 1860 |
also also 1861 1866 1869 1872 | also, 1859 1860 |
probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would
....... 1861 1866 1869 1872 | have to 1859 1860 |
migrate, and no closely consecutive record of their modifications could be preserved in any one formation. |
|
Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy
plainly leads to the plainly leads to the 1861 1866 1869 1872 |
leads me to 1859 1860 |
belief belief 1861 1866 1869 1872 | believe 1859 1860 |
that it would be chiefly these far-ranging
species, species, 1866 1869 1872 | species 1859 1860 1861 |
though only some of them, which though only some of them, which 1866 1869 1872 |
which 1859 1860 1861 |
would oftenest produce new varieties; and the varieties would at first
generally generally 1859 1860 1861 1866 1869 | generally 1872 |
be local or confined to one place, but if possessed of any decided advantage, or when further modified and improved, they would slowly spread and supplant their parent-forms. When such varieties returned to their ancient homes, as they would differ from their former
state, state, 1859 1860 1861 1866 1869 | state 1872 |
in
|