and laid a new covering of rocks over the earth's surface for a subsequent
period of relative quiet; and so the process was continued. By this
account, Cuvier endeavored to reconcile the doctrine of supernatural
creation and intervention with the obvious facts that organisms have
differed at various times in the earth's history. Although he saw that
animals of successive periods displayed similar structures, like the
skeleton of vertebrates, which testified to some connection, Cuvier could
not bring himself to believe that this connection was a genealogical one.

Mainly through the influence of the renowned English man of science,
Charles Lyell, the students of the earth came to the conclusion that its
manifold structures had developed by a slow and orderly process that was
entirely natural; for they found no evidence of any sudden and drastic
world-wide remodeling such as that postulated by the Cuvierian hypothesis
of catastrophe. The battle waged for many years; but now naturalists
believe that the forces, of nature, whose workings may be seen on all
sides at the present time, have reconstructed the continents and ocean
beds in the past in the same way that they work to-day. The long name of
"uniformitarianism" is given to Lyell's doctrine, which has exerted an
influence upon knowledge far outside the department of geology. Darwin
tells us how much he himself was impressed by it, and how it led him to
study the factors at work upon organic things to see if he could discern
evidence of a biological uniformitarianism, according to which the past
history of living things might be interpreted through an understanding of
their present lives.

* * * * *

What, now, are the reasons why the palæontological evidence is not
complete and why it cannot be? In the first place the seeker after fossil