|
The excerpt represents the core issue or deciding factor on which you must meditate, and is drawn from On the Origin of Species by Charles Darwin: 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
On the Origin of Species |
