in; or, to their notions of Mr. Darwin's views and not to what
they really are. An excellent example of this class of difficulties
is to be found in Mr. Mivart's chapter on "Independent Similarities
of Structure." Mr. Mivart says that these cannot be explained by
an "absolute and pure Darwinian," but "that an innate power and
evolutionary law, aided by the corrective action of natural selection,
should have furnished like needs with like aids, is not at all
improbable" (p. 82).

I do not exactly know what Mr. Mivart means by an "absolute and
pure Darwinian;" indeed Mr. Mivart makes that creature hold so many
singular opinions that I doubt if I can ever have seen one alive. But
I find nothing in his statement of the view which he imagines to
be originated by himself, which is really inconsistent with what I
understand to be Mr. Darwin's views.

I apprehend that the foundation of the theory of natural selection is
the fact that living bodies tend incessantly to vary. This variation
is neither indefinite, nor fortuitous, nor does it take place in all
directions, in the strict sense of these words.

Accurately speaking, it is not indefinite, nor does it take place in
all directions, because it is limited by the general characters of the
type to which the organism exhibiting the variation belongs. A whale
does not tend to vary in the direction of producing feathers, nor a
bird in the direction of developing whalebone. In popular language
there is no harm in saying that the waves which break upon the
sea-shore are indefinite, fortuitous, and break in all directions.
In scientific language, on the contrary, such a statement would be
a gross error, inasmuch as every particle of foam is the result of
perfectly definite forces, operating according to no less definite
laws. In like manner, every variation of a living form, however
minute, however apparently accidental, is inconceivable except as the
expression of the operation of molecular forces or "powers" resident
within the organism. And, as these forces certainly operate according
to definite laws, their general result is, doubtless, in accordance
with some general law which subsumes them all. And there appears to
be no objection to call this an "evolutionary law." But nobody is the
wiser for doing so, or has thereby contributed, in the least degree,
to the advance of the doctrine of evolution, the great need of which
is a theory of variation.

When Mr. Mivart tells us t