Origin of Species Variorum

↑ 1 blocks not present in 1866 1869 1872; present in 1859 1860 1861

If the climate, since the Glacial period, has ever been in any degree warmer than at present (as some geologists in the United States believe to have been the case, chiefly from the distribution of the fossil Gnathodon), then the arctic and temperate productions will at a very late period have marched a little further north, and subsequently have retreated to their present homes; but I have met with no satisfactory evidence with respect to this intercalated slightly warmer period, since the Glacial period.

→ moved first southward and afterwards backwards to the north, in unison with the changing climate, they will not 1866 1869 1872

during their long southern migration and re-migration northward, will 1859 1860 1861

→ during their long migrations to any great diversity of temperature, 1866

to nearly the same climate, 1859 1860 1861

during their long migrations to any great diversity of temperature; 1869 1872

→ they will all have migrated 1866

is especially to be noticed, they will have kept 1859 1860 1861

they all migrated 1869 1872

→ this we find has been the case; 1859 1860 1861 1866 1869

they have been modified; 1872

→ one with another, though 1866 1869 1872

though very 1859 1860 1861

→ or sub-species, and some as certainly 1866 1869

and some few are 1859 1860

and many are 1861

or sub-species, and some as 1872

→ each other on the several ranges. 1866 1869 1872

species. 1859 1860 1861

→ illustrating what, as I believe, actually took place during the Glacial period, I 1859 1860 1861 1866

the foregoing illustration I have 1869 1872

migration across the

low

....

intervening

tracts, since

lowlands, now

become too warm for their existence. ↑

The

As the

arctic

forms,

forms

→moved first southward and afterwards backwards to the north, in unison with the changing climate, they will not have been exposed →during their long migrations to any great diversity of temperature,

and,

and

as →they will all have migrated in a body

together;

together,

consequently

....

their mutual relations will not have been much

disturbed,

disturbed.

and,

Hence,

in accordance with the principles inculcated in this volume,

they

these forms

will not have been liable to much modification. But with

our

the

Alpine productions, left isolated from the moment of the returning warmth, first at the bases and ultimately on the summits of the mountains, the case will have been somewhat

dif-

....

ferent;

different;

for it is not likely that all the same arctic species will have been left on

mountain ranges

mountain-ranges

distant

far distant

from each other, and have survived there ever since; they

will

will,

also

also,

in all

probability

probability,

have become mingled with ancient Alpine species, which must have existed on the mountains before the commencement of the Glacial epoch, and which during

the

its

coldest period will have been temporarily driven down to the plains; they will, also, have been

subsequently exposed

exposed

to somewhat different climatal influences. Their mutual relations will thus have been in some degree disturbed; consequently they will have been liable to modification; and →this we find has been the case; for if we compare the present Alpine plants and animals of the several great European

mountain-ranges,

mountain-ranges

→one with another, though many of the species

are

remain

still remain

identically the same, some

present

exist as

varieties, some

are ranked

....