Origin of Species Variorum

→ OMIT 1869 1872

I do not think that 1859 1860 1861 1866

→ far from insuperable; though 1869 1872

insuperable; though they often are 1859 1860 1861 1866

→ they are often great. 1869 1872

extremely grave. 1859

extremely great. 1860 1861 1866

→ a part the last 1872

has been the influence of the modern 1859 1860 1861 1866

a part the 1869

which I am fully convinced simultaneously affected the whole world, or at least great meridional belts. 1859 1860

which I am fully convinced simultaneously affected the whole world, or at least great longitudinal belts. 1861 1866

has played, which affected even the equatorial regions, and which, during the alternations of the cold in the north and south, allowed the productions of opposite hemispheres to mingle, and left some of them stranded in all parts of the world on the mountain-summits. 1869

→ the several species belonging to the same genus, 1872

allied species, 1859 1860 1861 1866

the several species belong- ing to the same genus, 1869

→ 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

→ OMIT 1872

as we do find, 1859 1860 1861 1866 1869

enormous periods of time

being

having been

thus granted for their migration, →OMIT the difficulties are →far from insuperable; though in this case,

and

in that of the individuals of the same species, →they are often great.

As exemplifying the effects of climatal changes on distribution, I have attempted to show how important →a part the last Glacial

period,

period

→has played, which affected even the equatorial regions, and which, during the alternations of the cold in the north and south, allowed the productions of opposite hemispheres to mingle, and left some of them stranded on the mountain-summits in all parts of the world. As showing how diversified are the means of occasional transport, I have discussed at some little length the means of dispersal of fresh-water productions.

If the difficulties be not insuperable in admitting that in the long course of time

the

all the

individuals of the same species, and likewise of →the several species belonging to the same genus, have proceeded from 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

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

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

→OMIT some groups of beings greatly, and some only slightly

modified,—

modified;—

some

deve- loped

developed

in great force, some