division of the animal kingdom, (the Acrita of his arrangement,)
there is a much quicker advance of forms towards the next above it,
than is to be seen in subsequent departments. There is, indeed, to
the most ordinary observation, a rapidity and force in the
productive powers of the lowest animals, which might well suggest
an explanation of that rush of life which seems to be indicated in
the slate and Silurian rocks. With regard to the so-called early
occurrence of fishes partaking of the saurian character, I would
say that their occurrence a full formation after the earliest and
simplest fishes, is, considering how little we know of the space of
time represented by a formation, not early: their being later in
any degree is the fact mainly important. The subsequent rise of
new orders of fishes, fully piscine in character, may be explained
by the supposition of their having been developed, as is most
likely, from a different portion of the inferior sub-kingdom. In
short, all the objections which have been made to the great fact of
a general progress of organic development throughout the geological
ages, will be found, on close examination, to refer merely to
doubtful appearances of small moment, which vanish into nothing
when rightly understood."

Upon some of the chief points here involved, it may be remarked that the
most eminent physiologists are not agreed; they are not agreed that
animals can be arranged in a series, passing from lower to higher; nor
that animals of a higher kind in the embryo state pass through the
successive stages of the lower kinds; the character of these stages, in
the asserted doctrine, being taken from the brain and heart, and man
being the highest point of the series. There are physiologists too who
deny that the brain of the human embryo at any period, however early,
resembles the brain of any mollusk or of any articulata. It never, they