nt ponds,
and, then getting a hearty meal of fish, analogy makes me believe
that it would have rejected the seeds in the pellet in a fit state for
germination.

In considering these several means of distribution, it should be
remembered that when a pond or stream is first formed, for instance on a
rising islet, it will be unoccupied; and a single seed or egg will have
a good chance of succeeding. Although there will always be a struggle
for life between the inhabitants of the same pond, however few in kind,
yet as the number even in a well-stocked pond is small in comparison
with the number of species inhabiting an equal area of land, the
competition between them will probably be less severe than between
terrestrial species; consequently an intruder from the waters of a
foreign country would have a better chance of seizing on a new place,
than in the case of terrestrial colonists. We should also remember that
many fresh-water productions are low in the scale of nature, and we have
reason to believe that such beings become modified more slowly than the
high; and this will give time for the migration of aquatic species.
We should not forget the probability of many fresh-water forms having
formerly ranged continuously over immense areas, and then having become
extinct at intermediate points. But the wide distribution of fresh-water
plants, and of the lower animals, whether retaining the same identical
form, or in some degree modified, apparently depends in main part on the
wide dispersal of their seeds and eggs by animals, more especially by
fresh-water birds, which have great powers of flight, and naturally
travel from one piece of water to another.

ON THE INHABITANTS OF OCEANIC ISLANDS.

We now come to the last of the three classes of facts, which I have
selected as presenting the greatest amount of difficulty with respect to
distribution, on the view that not only all the individuals of the
same species have migrated from some one area, but that allied species,
although now inhabiting the most distant points, have proceeded from a
single area, the birthplace of their early progenitors. I have already
given my reasons for disbelieving in continental extensions within the
period of existing species on so enormous a scale that all the many
islands of the several oceans were thus stocked with their present
terrestrial inhabitants. This view removes many difficulties, but it
does not accord with all the facts in regard t