en a nodding acquaintance. "The idea of a quasi-superhuman
intelligence presiding over the forces of the living is met with in the
field of regeneration." Echoes of the Cartesian idea of the soul seem to
ring in this statement; but it could not have been written by anyone who
had mastered the Aristotelian or the Scholastic explanation of matter
and form. But let us take this question of Regeneration; the power which
all living things have, in some measure, though in very different
measure, of reconstructing themselves when injured. It has been dealt
with in a masterly manner by Driesch; and we may at once say that we do
not think that Loeb has in any way contraverted his argument, nor even
entered the first line of defence of that which is built up around what
he calls by the somewhat forbidding name of "Harmonious-Equipotential
System."

Let us take one particular example, a very remarkable one, which has
been cited by both writers--Wolff's experiment on the lens of the eye.
The lens is just behind the pupil or central aperture in the iris or
coloured ring at the front of the eye, and behind the cornea which is to
the eye what a watch-glass is to a watch. If the lens of the eye be
removed from a newt, as it is from human beings in the operation for
cataract, the animal will grow another one. How does it do it? In
certain cases a tiny fragment of the lens has been left behind after the
operation, and the new one grows from that. This is sufficiently
wonderful, but by no means so wonderful as what happens in other cases
in which the entire lens has been removed and the new lens grows from
the outer pigmented layer of the margin of the iris. To the unbiological
reader one source of origin will not seem more wonderful than the other,
but there is really a vast distinction between them. At an early stage
in the development of the embryo, the cells composing it become
divisible into three layers. It is even possible, as Loeb maintains,
that this differentiation is present in the unsegmented ovum, in which
case the facts to be detailed become still more remarkable and
significant. These layers are known as epi-, meso-, and hypo-blast; and
from each one of them arise certain portions of the body, and certain
portions only. It would be as remarkable to a biologist to find these
layers not breeding true as it would to a fowl-fancier to discover that
the eggs of his Buff Orpingtons were producing young turkeys or ducks.
Now the l