Comparison with 1859 |
|
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, thus, 1859 | thus 1860 1861 1866 1869 1872 |
Messrs. Messrs. 1859 1860 1861 | Sir C. 1866 1869 1872 |
Lyell and
Dawson Dawson 1859 1860 1861 | Dr. Dawson 1866 1869 1872 |
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 1859 1860 1861 |
So that, if such species 1866 1869 |
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 probably 1859 1860 1861 1866 | probably 1869 1872 |
include all the fine intermediate gradations which must on
my my 1859 1860 1861 1866 | our 1869 1872 |
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 very 1859 1860 | very 1861 1866 1869 1872 |
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 close 1859 1860 1861 | the closest 1866 1869 1872 |
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 underlying 1859 1860 1861 1866 |
older and underlying 1869 1872 |
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 at all 1859 1860 1861 | at all 1866 1869 1872 |
necessarily be strictly intermediate between them in all
points of structure. points of structure. 1859 1860 1861 |
respects. 1866 1869 1872 |
So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of
a a 1859 1860 1861 1866 | the same 1869 1872 |
formation, and unless we obtained numerous transitional gradations, we should not recognise their
relationship, relationship, 1859 1860 | blood-relationship, 1861 1866 1869 1872 |
and should consequently
be compelled to be compelled to 1859 1860 1861 1866 1869 |
OMIT 1872 |
rank them
all all 1859 1860 1861 1866 | all 1869 1872 |
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
and others into the rank of varieties; and on this view we do find the kind of evidence of change which on
my my 1859 1860 1861 1866 | the 1869 1872 |
theory we ought to find. |
Text in this page (from paragraph 2900, sentence 210 to paragraph 2900, sentence 210, word 43) is not present in 1859 |