oped. And when we come to the primitive germs, so
minute as to be visible only through the microscope, no outward
distinction, perhaps, is any longer perceptible, and the radical
difference of their internal organization is indicated only by the fact,
to be verified by subsequent observation, that the two are invariably
developed into perfectly distinct animals, belonging respectively to the
same races with their parents. A theorist, whose whole system is based
upon the invariable operation of natural agencies, cannot reasonably
object to this conclusion.

That our statements in the course of this argument may not appear of the
same questionable character as those advanced by our author, we will
fortify them with a few brief citations from a work of such
unquestionable authority as the Lectures of Professor Owen.

"No doubt the minute infusoria, which seem to have their
development arrested at the first or nearest stage from the
primitive cell formation, offer close and striking analogies to the
primitive cells out of which the higher animals and all their
tissues are developed; but the very [first] step which the
infusoria take beyond the primitive cell stage invests them with a
specific character as independent and distinct in its nature as
that of the highest and most complicated organisms. No mere organic
cell, destined for ulterior changes in a living organization, has a
mouth armed with teeth, or provided with long tentacula; I will not
lay stress on the alimentary canal and appended stomachs, which
many still regard as 'sub judice'; but the endowment of distinct
organs of generation, for propagating their kind by fertile ova,
raises the polygastric infusoria much above the mere organic
cell."--pp. 25, 26.

"In comparing the several stages in the very interesting
development of the _cyanaea aurita_ to the infusoria and polypes, it
must be understood that such comparisons are warranted only by a
similarity of outward form, and of the instruments of locomotion
and prehension. The essential internal organization of the
persistent lower forms of the _zooephyta_ is entirely wanting in the
transitory states of the higher ones. A progress through the
inferior groups is sketched out, but no actual transmutation of
species is effected. The young medusa, before it attains its
destined condition of