tion; to rudimentary structures; to
homology; to mimicry, &c.--Consequent utility of the theory.--Its wide
acceptance.--Reasons for this, other than, and in addition to, its
scientific value.--Its simplicity.--Its bearing on religious
questions.--_Odium theologicum_ and _odium antitheologicum_.--The
antagonism supposed by many to exist between it and theology neither
necessary nor universal.--Christian authorities in favour of
evolution.--Mr. Darwin's "Animals and Plants under
Domestication."--Difficulties of the Darwinian theory enumerated.

The great problem which has so long exercised the minds of naturalists,
namely, that concerning the origin of different kinds of animals and
plants, seems at last to be fairly on the road to receive--perhaps at no
very distant future--as satisfactory a solution as it can well have.

But the problem presents peculiar difficulties. The birth of a "species"
has often been compared with that of an "individual." The origin, however,
of even an individual animal or plant (that which determines an embryo to
evolve itself,--as, _e.g._, a spider rather than a beetle, a rose-plant {2}
rather than a pear) is shrouded in obscurity. _A fortiori_ must this be the
case with the origin of a "species."

Moreover, the analogy between a "species" and an "individual" is a very
incomplete one. The word "individual" denotes a concrete whole with a real,
separate, and distinct existence. The word "species," on the other hand,
denotes a peculiar congeries of characters, innate powers and qualities,
and a certain nature realized indeed in individuals, but having no separate
existence, except ideally as a thought in some mind.

Thus the birth of a "species" can only be compared metaphorically, and very
imperfectly, with that of an "individual."

Individuals as _individuals_, actually and directly produce and bring forth
other individuals; but no "congeries of characters" no "common nature" _as
such_, can directly bring forth another "common nature," because, _per se_,
it has no existence (other than ideal) apart from the individuals in which
it is manifested.

The problem then is, "by what combination of natural laws does a new
'common nature' appear upon the scene of realized existence?" _i.e._ how is
an individual embodying such new characters produced?

For the approximation we have of late made towards the solution of this
problem, we are mainly indebted to the inva