they have devoured the fruit, drop the stone into the ground. Captain
Cook, in his account of the volcanic island of Tanna, one of the New
Hebrides, which he visited in his second voyage, makes the following
interesting observation:--"Mr. Forster, in his botanical excursion this
day, shot a pigeon, in the craw of which was a wild nutmeg."[865] It is
easy, therefore, to perceive, that birds in their migrations to great
distances, and even across seas, may transport seeds to new isles and
continents.

The sudden deaths to which great numbers of frugivorous birds are
annually exposed must not be omitted as auxiliary to the transportation
of seeds to new habitations. When the sea retires from the shore, and
leaves fruits and seeds on the beach, or in the mud of estuaries, it
might, by the returning tide, wash them away again, or destroy them by
long immersion; but when they are gathered by land birds which frequent
the sea side, or by waders and water-fowl, they are often borne inland;
and if the bird to whose crop they have been consigned is killed, they
may be left to grow up far from the sea. Let such an accident happen but
once in a century, or a thousand years, it will be sufficient to spread
many of the plants from one continent to another; for in estimating the
activity of these causes, we must not consider whether they act slowly
in relation to the period of our observation, but in reference to the
duration of species in general.

Let us trace the operation of this cause in connection with others. A
tempestuous wind bears the seeds of a plant many miles through the air,
and then delivers them to the ocean; the oceanic current drifts them to
a distant continent; by the fall of the tide they become the food of
numerous birds, and one of these is seized by a hawk or eagle, which,
soaring across hill and dale to a place of retreat, leaves, after
devouring its prey, the unpalatable seeds to spring up and flourish in a
new soil.

The machinery before adverted to, is so capable of disseminating seeds
over almost unbounded spaces, that were we more intimately acquainted
with the economy of nature, we might probably explain all the instances
which occur of the aberration of plants to great distances from their
native countries. The real difficulty which must present itself to every
one who contemplates the present geographical distribution of species,
is the small number of exceptions to the rule of the non-intermixture of