ble? Are all the grandest and most interesting problems
which offer themselves to the geological student essentially insoluble?
Is he in the position of a scientific Tantalus--doomed always to thirst
for a knowledge which he cannot obtain? The reverse is to be hoped; nay,
it may not be impossible to indicate the source whence help will come.

In commencing these remarks, mention was made of the great obligations
under which the naturalist lies to the geologist and palaeontologist.
Assuredly the time will come when these obligations will be repaid
tenfold, and when the maze of the world's past history, through which
the pure geologist and the pure palaeontologist find no guidance, will be
securely threaded by the clue furnished by the naturalist.

All who are competent to express an opinion on the subject are, at
present, agreed that the manifold varieties of animal and vegetable form
have not either come into existence by chance, nor result from
capricious exertions of creative power; but that they have taken place
in a definite order, the statement of which order is what men of science
term a natural law. Whether such a law is to be regarded as an
expression of the mode of operation of natural forces, or whether it is
simply a statement of the manner in which a supernatural power has
thought fit to act, is a secondary question, so long as the existence of
the law and the possibility of its discovery by the human intellect are
granted. But he must be a half-hearted philosopher who, believing in
that possibility, and having watched the gigantic strides of the
biological sciences during the last twenty years, doubts that science
will sooner or later make this further step, so as to become possessed
of the law of evolution of organic forms--of the unvarying order of that
great chain of causes and effects of which all organic forms, ancient
and modern, are the links. And then, if ever, we shall be able to begin
to discuss, with profit, the questions respecting the commencement of
life, and the nature of the successive populations of the globe, which
so many seem to think are already answered.

The preceding arguments make no particular claim to novelty; indeed they
have been floating more or less distinctly before the minds of
geologists for the last thirty years; and if, at the present time, it
has seemed desirable to give them more definite and systematic
expression, it is because palaeontology is every day assuming a