Gorilla differs slightly from Man in the mode of interlacing of the
long flexor tendons: and the lower apes differ from the Gorilla in
exhibiting yet other, sometimes very complex, arrangements of the same
parts, and occasionally in the absence of the accessory fleshy bundle.

Throughout all these modifications it must be recollected that the foot
loses no one of its essential characters. Every Monkey and Lemur
exhibits the characteristic arrangement of tarsal bones, possesses a
short flexor and short extensor muscle, and a 'peronaeus longus'.
Varied as the proportions and appearance of the organ may be, the
terminal division of the hind limb remains, in plan and principle of
construction, a foot, and never, in those respects, can be confounded
with a hand.

Hardly any part of the bodily frame, then, could be found better
calculated to illustrate the truth that the structural differences
between Man and the highest Ape are of less value than those between
the highest and the lower Apes, than the hand or the foot, and yet,
perhaps, there is one organ the study of which enforces the same
conclusion in a still more striking manner--and that is the Brain.

But before entering upon the precise question of the amount of
difference between the Ape's brain and that of Man, it is necessary
that we should clearly understand what constitutes a great, and what a
small difference in cerebral structure; and we shall be best enabled to
do this by a brief study of the chief modifications which the brain
exhibits in the series of vertebrate animals.

The brain of a fish is very small, compared with the spinal cord into
which it is continued, and with the nerves which come off from it: of