Comparison with 1860 |
|
CHAPTER XII.
|
GEOGRAPHICAL DISTRIBUTION—
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. chapters. 1859 1860 | chapter. 1861 1866 1869 1872 |
↑Subtitle not present 1859 1860 1861 |
Fresh-water
Productions
.
1866 1869 1872 |
|
AS
lakes and 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
as the sea is apparently a still more impassable
barrier, that they never would
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. I well remember, when first collecting in the fresh waters of Brazil,
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 this power in
fresh-water productions of ranging widely, though so unexpected,
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;
and
liability to wide dispersal would follow from this capacity as an almost necessary consequence.
|
CHAPTER
XII. XII. 1859 1860 1861 1866 1869 | XIII. 1872 |
|
GEOGRAPHICAL DISTRIBUTION—
continued
.
continued
.
1859 1860 1861 1866 1872 |
continued.
1869 |
|
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
chapter. chapter. 1861 1866 1869 1872 | chapters. 1859 1860 |
↑Subtitle not present 1859 1860 1861 |
Fresh-water
Productions
.
1866 1869 1872 |
|
AS AS 1859 1860 1861 1872 | As 1866 1869 |
lakes and
river-systems river-systems 1859 1860 1861 1866 1869 | river systems 1872 |
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 1859 1860 1861 1872 | and, 1866 1869 |
as the sea is apparently a still more
impassable impassable 1859 1860 1861 1866 | formidable 1869 1872 |
barrier, that they
never would never would 1859 1860 1861 1866 1869 | would never 1872 |
have extended to distant countries. But the case is exactly the reverse. Not only have many fresh-water species, belonging to
quite quite 1859 1860 1861 1866 1869 | quite 1872 |
different classes, an enormous range, but allied species prevail in a remarkable manner throughout the world.
I well remember, when first collecting in the fresh waters of Brazil, I well remember, when first collecting in the fresh waters of Brazil, 1859 1860 1861 1866 1869 |
When first collecting in the fresh waters of Brazil, I well remember 1872 |
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
this power in this power in 1859 1860 1861 1866 1869 |
the wide ranging power of 1872 |
fresh-water productions
of ranging widely, though so unexpected, of ranging widely, though so unexpected, 1859 1860 1861 1866 1869 |
OMIT 1872 |
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; 1859 1860 1861 1866 1869 | stream 1872 |
and and 1859 1860 1861 1866 1869 |
within their own countries; and 1872 |
liability to wide dispersal would follow from this capacity as an almost necessary consequence.
|