h have given rise to them, masses of
Cretaceous rock which formed the bottom of the sea before those mountains
existed. It is therefore clear that the elevatory forces which gave rise
to the mountains operated subsequently to the Cretaceous epoch; and that
the mountains themselves are largely made up of the materials deposited in
the sea which once occupied their place. As we go back in time, we meet
with constant alternations of sea and land, of estuary and open ocean;
and, in correspondence with these alternations, we observe the changes in
the fauna and flora to which I have referred.

But the inspection of these changes gives us no right to believe that
there has been any discontinuity in natural processes. There is no trace
of general cataclysms, of universal deluges, or of sudden destructions of
a whole fauna or flora. The appearances which were formerly interpreted in
that way have all been shown to be delusive, as our knowledge has
increased, and as the blanks which formerly appeared to exist between the
different formations have been filled up. That there is no absolute break
between formation and formation, that there has been no sudden
disappearance of all the forms of life and replacement of them by others,
but that changes have gone on slowly and gradually, that one type has died
out and another has taken its place, and that thus, by insensible degrees,
one fauna has been replaced by another, are conclusions strengthened by
constantly increasing evidence. So that within the whole of the immense
period indicated by the fossiliferous stratified rocks there is assuredly
not the slightest proof of any break in the uniformity of nature's
operations, no indication that events have followed other than a clear and
orderly sequence.

That, I say, is the natural and obvious teaching of the circumstantial
evidence contained in the stratified rocks. I leave you to consider how
far, by any ingenuity of interpretation, by any stretching of the meaning
of language, it can be brought into harmony with the Miltonic hypothesis.

ON THE PHYSICAL BASIS OF LIFE

In order to make the title of this discourse generally intelligible, I
have translated the term "protoplasm," which is the scientific name of the
substance of which I am about to speak, by the words "the physical basis
of life." I suppose that, to many, the idea that there is such a thing as
a physical basis, or matter, of life may be novel, so widely spread i