are grounded, will not harmonize readily with a doctrine so thoroughly
naturalistic as that of Mr. Darwin. Though it is just possible that one who
regards the kinds of elementary matter, such as oxygen and hydrogen, and
the definite compounds of these elementary matters, and their compounds
again, in the mineral kingdom, as constituting species, in the same sense,
fundamentally, as that of animal and vegetable species, might admit an
evolution of one species from another in the latter as well as the former
case.

Between the doctrines of this volume and those of the other great
naturalist whose name adorns the title-page of this journal, the widest
divergence appears. It is interesting to contrast the two, and, indeed, is
necessary to our purpose; for this contrast brings out most prominently,
and sets in strongest light and shade, the main features of the theory of
the origination of species by means of Natural Selection.

The ordinary and generally-received view assumes the independent, specific
creation of each kind of plant and animal in a primitive stock, which
reproduces its like from generation to generation, and so continues the
species. Taking the idea of species from this perennial succession of
essentially similar individuals, the chain is logically traceable back to a
local origin in a single stock, a single pair, or a single individual, from
which all the individuals composing the species have proceeded by natural
generation. Although the similarity of progeny to parent is fundamental in
the conception of species, yet the likeness is by no means absolute; all
species vary more or less, and some vary remarkably--partly from the
influence of altered circumstances, and partly (and more really) from
unknown constitutional causes which altered conditions favor rather than
originate. But these variations are supposed to be mere oscillations from a
normal state, and in Nature to be limited if not transitory; so that the