formations, this is almost the only allusion that has been made to the
fossils which constitute so important a part of geological science. It
is now to be explained that from an early period, that is, from the
metamorphic deposit to the close of the rock series, each formation is
found to enclose remains of the organic beings, plants, and animals,
which flourished upon earth during the time they were forming; and these
organisms, or such parts of them as were of sufficient solidity, have
been in many instances preserved with the utmost fidelity, although for
the most part converted into the substance of the enclosing mineral. The
rocks may be thus said to form a kind of history of the organic
departments of nature apparently from near their beginning to the
present time. It is upon the commencement and progress of life under
these circumstances that the author of the _Vestiges of Creation_ has
put forth some of his most startling and controversial propositions; but
before noticing them it will be useful to prepare the way by shortly
describing the gradations of organic existences, following the same
order as observed in the rock series, by beginning with the lowest or
humblest forms of organization.


RISE AND PROGRESS OF PLANTS AND ANIMALS.

The interior of the earth reveals wonders not less impressive than those
of the skies. We have seen in the last section how the crust of our
globe is composed of successive layers or tiers of strata, rising
upward, terrace upon terrace, till we reach the present vegetable mould
or superficial platform of animated existence. In the aggregate these
formations or systems, marking the several epochs in nature's
development, may extend to a depth, as Dr. BUCKLAND conjectures, of ten
or fifteen miles below the surface, and each may be considered a vast