See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1872

OMIT 1869 1872
(generally of the more dominant forms of life), 1859 1860 1861 1866

in not only separating, but in apparently forming the 1869 1872
which separate our 1859 1860 1861 1866

related species within the same areas; 1869 1872
sub-genera, genera, and families; 1859 1860 1861 1866

linked together in 1869 1872
in 1859 1860 1861 1866

OMIT 1869 1872
linked together by affinity, 1859 1860 1861
linked together, 1866

of the regions, or both; according to the nature of the 1866 1869 1872
region; according to the nature of the 1859 1860 1861

the two or more 1869 1872
different 1859 1860 1861 1866

as we do find, 1859 1860 1861 1866 1869
OMIT 1872

in the several 1866 1869
in the different 1859 1860 1861
and this we do find in the several 1872

some one source; then
I think
....
all the grand leading facts of geographical distribution are explicable on the theory of
migration,
migration
OMIT together with subsequent modification and the multiplication of new forms. We can thus understand the high importance of barriers, whether of land or water, in not only separating, but in apparently forming the several zoological and botanical provinces. We can thus understand the
localisation
concentration
of related species within the same areas; and how it is that under different latitudes, for instance in South America, the inhabitants of the plains and mountains, of the forests, marshes, and deserts, are linked together in so mysterious a
manner
manner,
OMIT and are likewise linked to the extinct beings which formerly inhabited the same continent. Bearing in mind that the mutual
relations
relation
of organism to organism
are
is
of the highest importance, we can see why two areas having nearly the same physical conditions should often be inhabited by very different forms of life; for according to the length of time which has elapsed since
new inhabitants
new colonists
the colonists
entered one of the regions, or both; according to the nature of the communication which allowed certain forms and not others to enter, either in greater or lesser numbers; according or not, as those which entered happened to come
in
into
more or less direct competition with each other and with the
aborigines:
aborigines;
and according as the immigrants were capable of varying more or less rapidly, there would ensue in the two or more regions, independently of their physical conditions, infinitely diversified conditions of life,— there would be an almost endless amount of organic action and reaction,— and we should
find
find,
as we do find, some groups of beings greatly, and some only slightly
modified;—
modified,—
some
deve- loped
developed
in great force, some existing in scanty numbers— in the several great geographical provinces of the world.