Origin of Species Variorum

→ Thus 1869 1872

By these means, as I believe, 1859 1860 1861 1866

→ and New Zealand, may have 1872

New Zealand have 1859

New Zealand, have 1860 1861

and New Zealand, 1866

and New Zealand, might have 1869

→ throughout the world on 1869 1872

on 1859 1860 1861 1866

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

I believe that the world has recently felt one of his great cycles of change; and that on this view, combined with modification through natural selection, a multitude of facts in the present distribution both of the same and of allied forms of life can be explained.

→ OMIT 1869 1872

may be said to 1859 1860 1861 1866

→ during another from 1872

from 1859 1860 1861 1866

afterwards from 1869

→ in both cases have reached 1869 1872

to have crossed at 1859 1860 1861 1866

→ the stream of life has 1869 1872

to have 1859 1860 1861 1866

→ than in the opposite direction, and has consequently more 1869 1872

so as to have 1859 1860 1861 1866

→ mountain summits, in 1872

mountain-summits, 1859 1860 1866 1869

mountain- summits, 1861

→ mountain fastnesses of 1872

mountain-fastnesses 1859 1860 1861 1866 1869

→ When first collecting in the fresh waters of Brazil, I well remember 1872

I well remember, when first collecting in the fresh waters of Brazil, 1859 1860 1861 1866 1869

→ the wide ranging power of 1872

this power in 1859 1860 1861 1866 1869

→ OMIT 1872

of ranging widely, though so unexpected, 1859 1860 1861 1866 1869

→ within their own countries; and 1872

and 1859 1860 1861 1866 1869

→ cases; of these, some of the most difficult to explain are presented by fish. 1872

cases. 1859 1860 1861 1866 1869

various points of the southern hemisphere by occasional means of transport, and by the

aid,

aid

as halting-places, of

existing and

....

now sunken

islands,

and

perhaps

the

commencement

the

Glacial

period,

icebergs.

→Thus the southern shores of America, Australia, →and New Zealand, may have

became

become

slightly tinted by the same peculiar forms of

vegetable

....

life.

Sir C. Lyell in a striking passage has speculated, in language almost identical with mine, on the effects of great alternations of climate →throughout the world on geographical distribution. And we have now seen that Mr.

Crolls

Croll's

conclusion that successive Glacial periods in the one hemisphere

coincided

coincide

with warmer periods in the opposite hemisphere, together with the admission of the slow modification of species, explains a multitude of facts in the distribution of the same and of the allied forms of life in all parts of the globe. ↑ The living waters →OMIT have flowed during

one short

certain

one

periods

period

from the north and →during another from the south, and →in both cases have reached the

equator;

equator:

but →the stream of life has flowed with greater force from the

north,

north

→than in the opposite direction, and has consequently more freely inundated the south. As the tide leaves its drift in horizontal lines,

though

....

rising higher on the shores where the tide rises highest, so have the living waters left their living drift on our →mountain summits, in

....

a line gently rising from the

arctic

Arctic

lowlands to a great

height

altitude

under the equator. The various beings thus left stranded may be compared with savage races of man, driven up and surviving in the →mountain fastnesses of

....

almost every land, which serve as a record, full of interest to us, of the former inhabitants of the surrounding lowlands.

CHAPTER

XII.

XIII.

GEOGRAPHICAL DISTRIBUTION—

continued.

continued .

Distribution of fresh-water productions— On the inhabitants of oceanic islands— Absence of Batrachians and of terrestrial Mammals— On the relation of the inhabitants of islands to those of the nearest mainland— On colonisation from the nearest source with subsequent modification— Summary of the last and present

chapters.

chapter.

Fresh-water

Productions.

Productions .

lakes and

river-systems

river systems

are separated from each other by barriers of land, it might have been thought that fresh-water productions would not have ranged widely within the same country,

and,

and

as the sea is apparently a still more

impassable

formidable

barrier, that they

never would

would never

have extended to distant countries. But the case is exactly the reverse. Not only have many fresh-water species, belonging to

quite

....

different classes, an enormous range, but allied species prevail in a remarkable manner throughout the world. →When first collecting in the fresh waters of Brazil, I well remember feeling much surprise at the similarity of the fresh-water insects, shells, &c., and at the dissimilarity of the surrounding terrestrial beings, compared with those of Britain.

But →the wide ranging power of fresh-water productions →OMIT can, I think, in most cases be explained by their having become fitted, in a manner highly useful to them, for short and frequent migrations from pond to pond, or from stream to

stream;

stream

→within their own countries; and liability to wide dispersal would follow from this capacity as an almost necessary consequence. We can here consider only a few →cases; of these, some of the most difficult to explain are presented by fish. It was formerly believed that the same fresh-water species never existed on two continents distant from each other. But Dr. Günther has lately shown that the Galaxias attenuatus inhabits Tasmania, New Zealand, the Falkland Islands, and the mainland of South America. This is a wonderful case, and probably indicates dispersal from an Antarctic centre during a former warm period. This case, however, is rendered in some degree less