Comparison with 1872 |
|
yet are far more closely
related related 1861 1866 1869 1872 | allied 1859 1860 |
to each other than are the species found in more widely separated formations;
so that here again we have undoubted evidence of change so that here again we have undoubted evidence of change 1869 1872 |
but to this subject I shall have to return 1859 1860 |
so that here again we have undoubted evidence of change, though not strictly of variation, 1861 1866 |
in the
direction required by the theory; but to this latter subject I shall return in the following direction required by the theory; but to this latter subject I shall return in the following 1872 |
following 1859 1860 |
direction required by my theory; but to this latter subject I shall have to return in the following 1861 1866 |
direction required by the theory; but to this latter subject I shall have to return in the following 1869 |
chapter. |
|
...OMIT 1866 1869 1872 |
One other consideration is worth notice: 1859 1860 1861 |
With With 1866 1869 1872 | with 1859 1860 1861 |
animals and plants that
....... 1866 1869 1872 | can 1859 1860 1861 |
propagate rapidly and
do do 1866 1869 1872 | are 1859 1860 1861 |
not
wander much, wander much, 1866 1869 1872 | highly locomotive, 1859 1860 1861 |
there is reason to suspect, as we have formerly seen, that their varieties are generally at first local; and that such local varieties do not spread widely and supplant their parent-forms until they have been modified and perfected in some considerable degree. According to this view, the chance of discovering in a formation in any one country all the early stages of transition between any two forms,
is small, for the successive changes are supposed to have been local or confined to some one spot. Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties; so
that, that, 1866 1869 1872 | that 1859 1860 1861 |
with shells and other marine animals, it is
probable probable 1869 1872 |
probably 1859 1860 |
highly probable that 1861 1866 |
that those which that those which 1872 |
those which have 1859 1860 1861 1866 |
that those which have 1869 |
had the widest range, far exceeding the limits of the known geological formations of Europe,
....... 1861 1866 1869 1872 | which 1859 1860 |
have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one
geological formation. |
|
It is a more important consideration, clearly
leading to the same result, as lately insisted on by Dr. Falconer, namely, that the periods
during which species have been undergoing
modification, though very
long as measured by years, have probably been
short in comparison with the periods
during which these same species
remained without undergoing any change. ↑2 blocks not present in 1859 1860 1861 1869 1872; present in 1866 | We may infer that this has been the case, from there being no inherent tendency in organic beings to become modified or to progress in structure, and from all modifications depending, firstly on long-continued variability, and secondly on changes in the physical conditions of life, or on changes in the habits and structure of competing species, or on the immigration of new forms; and such contingencies will supervene in most cases only after long intervals of time and at a slow rate.
These changes, moreover, in the organic and inorganic conditions of life will affect only a limited number of the inhabitants of any one area or country.
|
|
|
It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate
varieties, varieties, 1861 1866 1869 1872 | varieties 1859 1860 |
and thus proved to be the same species, until many specimens
are are 1869 1872 | have been 1859 1860 1861 1866 |
collected from many places; and
with with 1872 |
in the case of 1859 1860 1861 1866 1869 |
fossil species this
can can 1869 1872 | could 1859 1860 1861 1866 |
rarely be
done. done. 1872 |
effected by palæontologists. 1859 1860 1861 1866 1869 |
We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous,
fine, intermediate,
fossil links, by asking
|
yet are far more closely
allied allied 1859 1860 | related 1861 1866 1869 1872 |
to each other than are the species found in more widely separated formations;
but to this subject I shall have to return but to this subject I shall have to return 1859 1860 |
so that here again we have undoubted evidence of change, though not strictly of variation, 1861 1866 |
so that here again we have undoubted evidence of change 1869 1872 |
in the
following following 1859 1860 |
direction required by my theory; but to this latter subject I shall have to return in the following 1861 1866 |
direction required by the theory; but to this latter subject I shall have to return in the following 1869 |
direction required by the theory; but to this latter subject I shall return in the following 1872 |
chapter. |
|
One other consideration is worth notice: One other consideration is worth notice: 1859 1860 1861 |
OMIT 1866 1869 1872 |
with with 1859 1860 1861 | With 1866 1869 1872 |
animals and plants that
can can 1859 1860 1861 | can 1866 1869 1872 |
propagate rapidly and
are are 1859 1860 1861 | do 1866 1869 1872 |
not
highly locomotive, highly locomotive, 1859 1860 1861 | wander much, 1866 1869 1872 |
there is reason to suspect, as we have formerly seen, that their varieties are generally at first local; and that such local varieties do not spread widely and supplant their parent-forms until they have been modified and perfected in some considerable degree. According to this view, the chance of discovering in a formation in any one country all the early stages of transition between any two
forms, forms, 1859 1860 1861 1872 | such forms, 1866 1869 |
is small, for the successive changes are supposed to have been local or confined to some one spot. Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties; so
that that 1859 1860 1861 | that, 1866 1869 1872 |
with shells and other marine animals, it is
probably probably 1859 1860 |
highly probable that 1861 1866 |
probable 1869 1872 |
those which have those which have 1859 1860 1861 1866 |
that those which have 1869 |
that those which 1872 |
had the widest range, far exceeding the limits of the known geological formations of Europe,
which which 1859 1860 | which 1861 1866 1869 1872 |
have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any
one one 1859 1860 1866 1869 1872 | ony 1861 |
geological formation. ↑1 blocks not present in 1859 1860 1861; present in 1866 1869 1872 | It is a more important consideration, clearly
leading to the same result, as lately insisted on by Dr. Falconer, namely, that the periods
during which species have been undergoing
modification, though very
long as measured by years, have probably been
short in comparison with the periods
during which these same species
remained without undergoing any change.
|
|
|
It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate
varieties varieties 1859 1860 | varieties, 1861 1866 1869 1872 |
and thus proved to be the same species, until many specimens
have been have been 1859 1860 1861 1866 | are 1869 1872 |
collected from many places; and
in the case of in the case of 1859 1860 1861 1866 1869 |
with 1872 |
fossil species this
could could 1859 1860 1861 1866 | can 1869 1872 |
rarely be
effected by palæontologists. effected by palæontologists. 1859 1860 1861 1866 1869 |
done. 1872 |
We shall, perhaps, best perceive the improbability of our being enabled to connect species by
numerous, numerous, 1859 1860 1872 | numerous 1861 1866 1869 |
fine,
intermediate, intermediate, 1859 1860 1872 | intermediate 1861 1866 1869 |
fossil links, by asking
|