Comparison with 1869 |
|
suspected, suspected, 1859 1860 1861 1866 1869 | sus- pected, 1872 |
had not the trees
chanced to have chanced to have 1859 1860 1861 1866 1869 |
OMIT 1872 |
been preserved: thus,
Messrs.
Lyell and Dawson
found carboniferous beds 1400 feet thick in Nova Scotia, with ancient root-bearing strata, one above the
other, other, 1859 1860 1861 1866 1869 | other 1872 |
at no less than sixty-eight different levels. Hence, when the same species
occur occur 1859 1860 1861 1866 1869 | occurs 1872 |
at the bottom, middle, and top of a formation, the probability is that
they have they have 1859 1860 1861 1866 1869 | it has 1872 |
not lived on the same spot during the whole period of deposition, but
have have 1859 1860 1861 1866 1869 | has 1872 |
disappeared and reappeared, perhaps many times, during the same geological period.
So that, if such species So that, if such species 1866 1869 |
So that if such species 1859 1860 1861 |
Consequently if it 1872 |
were to undergo a considerable amount of modification during
any any 1859 1860 1861 1866 1869 |
the deposition of any 1872 |
one geological
period, period, 1859 1860 1861 1866 1869 | formation, 1872 |
a section would not probably
include all the fine intermediate gradations which must on my
theory have
existed existed 1859 1860 1861 1866 1869 | existed, 1872 |
between them, between them, 1859 1860 1861 1866 1869 | between them, 1872 |
but abrupt, though perhaps very
slight, changes of form. |
|
It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of difference between any two forms, they rank both as species, unless they are enabled to connect them together by close
intermediate
gradations. gradations. 1859 1860 1861 1866 1869 | gradations; 1872 |
And And 1859 1860 1861 1866 1869 | and 1872 |
this this 1859 1860 1861 1866 1869 | this, 1872 |
from the reasons just
assigned assigned 1859 1860 1861 1866 1869 | assigned, 1872 |
we can seldom hope to effect in any one geological section. Supposing B and C to be two species, and a third, A, to be found in an underlying
bed;
even if A were strictly intermediate between B and C, it would simply be ranked as a third and distinct species, unless at the same time it could be
most most 1859 1860 1861 1866 1869 | most 1872 |
closely connected
with with 1859 1860 1861 1866 1869 |
by intermediate varieties with 1872 |
either one or both
forms forms 1859 1860 1861 1866 1869 | forms. 1872 |
by by 1859 1860 1861 1866 1869 | by 1872 |
intermediate intermediate 1859 1860 1861 1866 1869 | intermediate 1872 |
varieties. varieties. 1859 1860 1861 1866 1869 | varieties. 1872 |
Nor should it be forgotten, as before explained, that A might be the actual progenitor of B and C, and yet
might might 1859 1860 1861 1866 1869 | would 1872 |
not at all
necessarily be strictly intermediate between them in all points of structure. So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of a
formation, and unless we obtained numerous transitional gradations, we should not recognise their relationship,
and should consequently
be compelled to be compelled to 1859 1860 1861 1866 1869 |
OMIT 1872 |
rank them all
as distinct species. |
|
It is notorious on what excessively slight differences many palæontologists have founded their species; and they do this the more readily if the specimens come from different sub-stages of the same formation. Some experienced conchologists are now sinking many of the very fine species of
D''Orbigny D''Orbigny 1869 | D'Orbigny 1859 1860 1861 1866 1872 |
and others into the rank of varieties; and on this view we do find the kind of evidence of change which on my
theory we ought to find. Look again at the later tertiary deposits, which include many shells believed by the majority of naturalists to be identical with existing species; but some excellent naturalists, as Agassiz and Pictet, maintain that all these tertiary species are specifically distinct, though the distinction
|
sus- pected, sus- pected, 1872 | suspected, 1859 1860 1861 1866 1869 |
had not the trees
...OMIT 1872 |
chanced to have 1859 1860 1861 1866 1869 |
been preserved:
thus thus 1860 1861 1866 1869 1872 | thus, 1859 |
Sir C. Sir C. 1866 1869 1872 | Messrs. 1859 1860 1861 |
Lyell and
Dr. Dawson Dr. Dawson 1866 1869 1872 | Dawson 1859 1860 1861 |
found carboniferous beds 1400 feet thick in Nova Scotia, with ancient root-bearing strata, one above the
other other 1872 | other, 1859 1860 1861 1866 1869 |
at no less than sixty-eight different levels. Hence, when the same species
occurs occurs 1872 | occur 1859 1860 1861 1866 1869 |
at the bottom, middle, and top of a formation, the probability is that
it has it has 1872 | they have 1859 1860 1861 1866 1869 |
not lived on the same spot during the whole period of deposition, but
has has 1872 | have 1859 1860 1861 1866 1869 |
disappeared and reappeared, perhaps many times, during the same geological period.
Consequently if it Consequently if it 1872 |
So that if such species 1859 1860 1861 |
So that, if such species 1866 1869 |
were to undergo a considerable amount of modification during
the deposition of any the deposition of any 1872 |
any 1859 1860 1861 1866 1869 |
one geological
formation, formation, 1872 | period, 1859 1860 1861 1866 1869 |
a section would not
....... 1869 1872 | probably 1859 1860 1861 1866 |
include all the fine intermediate gradations which must on
our our 1869 1872 | my 1859 1860 1861 1866 |
theory have
existed, existed, 1872 | existed 1859 1860 1861 1866 1869 |
....... 1872 | between them, 1859 1860 1861 1866 1869 |
but abrupt, though perhaps
....... 1861 1866 1869 1872 | very 1859 1860 |
slight, changes of form. |
|
It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of difference between any two forms, they rank both as species, unless they are enabled to connect them together by
the closest the closest 1866 1869 1872 | close 1859 1860 1861 |
intermediate
gradations; gradations; 1872 | gradations. 1859 1860 1861 1866 1869 |
and and 1872 | And 1859 1860 1861 1866 1869 |
this, this, 1872 | this 1859 1860 1861 1866 1869 |
from the reasons just
assigned, assigned, 1872 | assigned 1859 1860 1861 1866 1869 |
we can seldom hope to effect in any one geological section. Supposing B and C to be two species, and a third, A, to be found in an
older and underlying older and underlying 1869 1872 |
underlying 1859 1860 1861 1866 |
bed; bed; 1859 1860 1869 1872 |
and older bed; 1861 1866 |
even if A were strictly intermediate between B and C, it would simply be ranked as a third and distinct species, unless at the same time it could be
....... 1872 | most 1859 1860 1861 1866 1869 |
closely connected
by intermediate varieties with by intermediate varieties with 1872 |
with 1859 1860 1861 1866 1869 |
either one or both
forms. forms. 1872 | forms 1859 1860 1861 1866 1869 |
....... 1872 | by 1859 1860 1861 1866 1869 |
....... 1872 | intermediate 1859 1860 1861 1866 1869 |
....... 1872 | varieties. 1859 1860 1861 1866 1869 |
Nor should it be forgotten, as before explained, that A might be the actual progenitor of B and C, and yet
would would 1872 | might 1859 1860 1861 1866 1869 |
not
....... 1866 1869 1872 | at all 1859 1860 1861 |
necessarily be strictly intermediate between them in all
respects. respects. 1866 1869 1872 |
points of structure. 1859 1860 1861 |
So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of
the same the same 1869 1872 | a 1859 1860 1861 1866 |
formation, and unless we obtained numerous transitional gradations, we should not recognise their
blood-relationship, blood-relationship, 1861 1866 1869 1872 | relationship, 1859 1860 |
and should consequently
...OMIT 1872 |
be compelled to 1859 1860 1861 1866 1869 |
rank them
....... 1869 1872 | all 1859 1860 1861 1866 |
as distinct species. |
|
It is notorious on what excessively slight differences many palæontologists have founded their species; and they do this the more readily if the specimens come from different sub-stages of the same formation. Some experienced conchologists are now sinking many of the very fine species of
D'Orbigny D'Orbigny 1859 1860 1861 1866 1872 | D''Orbigny 1869 |
and others into the rank of varieties; and on this view we do find the kind of evidence of change which on
the the 1869 1872 | my 1859 1860 1861 1866 |
theory we ought to find. Look again at the later tertiary deposits, which include many shells believed by the majority of naturalists to be identical with existing species; but some excellent naturalists, as Agassiz and Pictet, maintain that all these tertiary species are specifically distinct, though the distinction
|