and catching insects or birds, they require some means of holding on
with their feet, otherwise they would be liable to continual falls, and
they are able to do this by means of their long finger-like toes and
large opposable thumbs, which grasp a branch almost as securely as a
bird grasps its perch. The true hands, on the contrary, are used chiefly
to climb with, and to swing the whole weight of the body from one branch
or one tree to another, and for this purpose the fingers are very long
and strong, and in many species they are further strengthened by being
partially joined together, as if the skin of our fingers grew together
as far as the knuckles. This shows that the separate action of the
fingers, which is so important to us, is little required by monkeys,
whose hand is really an organ for climbing and seizing food, while their
foot is required to support them firmly in any position on the branches
of trees, and for this purpose it has become modified into a large and
powerful grasping hand.

Another striking difference between monkeys and men is that the former
never walk with ease in an erect posture, but always use their arms in
climbing or in walking on all-fours like most quadrupeds. The monkeys
that we see in the streets dressed up and walking erect, only do so
after much drilling and teaching, just as dogs may be taught to walk in
the same way; and the posture is almost as unnatural to the one animal
as it is to the other. The largest and most man-like of the apes--the
gorilla, chimpanzee, and orang-outang--also walk usually on all-fours;
but in these the arms are so long and the legs so short that the body
appears half erect when walking; and they have the habit of resting on
the knuckles of the hands, not on the palms like the smaller monkeys,
whose arms and legs are more nearly of an equal length, which tends
still further to give them a semi-erect position. Still they are never
known to walk of their own accord on their hind legs only, though they