cted with the supposed pristine fluidity of the entire globe.

CHAPTER IX.

THEORY OF THE PROGRESSIVE DEVELOPMENT OF ORGANIC LIFE AT SUCCESSIVE
GEOLOGICAL PERIODS.

Theory of the progressive development of organic life--Evidence in
its support inconclusive--Vertebrated animals, and plants of the
most perfect organization, in strata of very high
antiquity--Differences between the organic remains of successive
formations--Comparative modern origin of the human race--The popular
doctrine of successive development not established by the admission
that man is of modern origin--Introduction of man, to what extent a
change in the system.

_Progressive development of organic life._--In the preceding chapters I
have considered whether revolutions in the general climate of the globe
afford any just ground of opposition to the doctrine that the former
changes of the earth which are treated of in geology belong to one
uninterrupted series of physical events governed by ordinary causes.
Against this doctrine some popular arguments have been derived from the
great vicissitudes of the organic creation in times past; I shall
therefore proceed to the discussion of such objections, which have been
thus formally advanced by the late Sir Humphrey Davy. "It is
impossible," he affirms, "to defend the proposition, that the present
order of things is the ancient and constant order of nature, only
modified by existing laws: in those strata which are deepest, and which
must, consequently, be supposed to be the earliest deposited, forms even
of vegetable life are rare; shells and vegetable remains are found in
the next order; the bones of fishes and oviparous reptiles exist in the
following class; the remains of birds, with those of the same genera
mentioned before, in the next order; those of quadrupeds of extinct
species in a still more recent class; and it is only in the loose and
slightly consolidated strata of gravel and sand, and which are usually
called diluvian formations, that the remains of animals such as now
people the globe are found, with others belonging to extinct species.
But, in none of these formations, whether called secondary, tertiary, or
diluvial, have the remains of man, or any of his works, been discovered;
and whoever dwells upon this subject must be convinced, that the present
order of things, and the comparatively recent existence of man as the
master of the globe, is as cert