ny
objects--of stones on a sea-beach, or of works of art; a natural
classification being simply an assemblage of objects in groups, so as
to express their most important and fundamental resemblances and
differences. No doubt Mr. Darwin believes that those resemblances and
differences upon which our natural systems or classifications of animals
and plants are based, are resemblances and differences which have been
produced genetically, but we can discover no reason for supposing that
he denies the existence of natural classifications of other kinds.

And, after all, is it quite so certain that a genetic relation may not
underlie the classification of minerals? The inorganic world has not
always been what we see it. It has certainly had its metamorphoses,
and, very probably, a long "Entwickelungsgeschichte" out of a nebular
blastema. Who knows how far that amount of likeness among sets of
minerals, in virtue of which they are now grouped into families and
orders, may not be the expression of the common conditions to which that
particular patch of nebulous fog, which may have been constituted by
their atoms, and of which they may be, in the strictest sense, the
descendants, was subjected?

It will be obvious from what has preceded, that we do not agree with
Professor Kolliker in thinking the objections which he brings forward
so weighty as to be fatal to Darwin's view. But even if the case were
otherwise, we should be unable to accept the "Theory of Heterogeneous
Generation" which is offered as a substitute. That theory is thus
stated:--

"The fundamental conception of this hypothesis is, that, under the
influence of a general law of development, the germs of organisms
produce others different from themselves. This might happen (1) by
the fecundated ova passing, in the course of their development, under
particular circumstances, into higher forms; (2) by the primitive and
later organisms producing other organisms without fecundation, out of
germs or eggs (Parthenogenesis)."

In favour of this hypothesis, Professor Kolliker adduces the well-known
facts of Agamogenesis, or "alternate generation"; the extreme
dissimilarity of the males and females of many animals; and of the
males, females, and neuters of those insects which live in colonies: and
he defines its relations to the Darwinian theory as follows:--

"It is obvious that my hypothesis is apparently very similar to
Darwin's, inasmuch as I also consider that the v