dren are born with
a real tail, which they move as the puppy does, according to their
emotional condition. Other features of the body point back to an even
earlier stage. The vermiform appendage--in which some recent medical
writers have vainly endeavoured to find a utility--is the shrunken
remainder of a large and normal intestine of a remote ancestor. This
interpretation of it would stand even if it were found to have a certain
use in the human body. Vestigial organs are sometimes pressed into a
secondary use when their original function has been lost. The danger of
this appendage in the human body to-day is due to the fact that it is
a blind alley leading off the alimentary canal, and has a very narrow
opening. In the ape the opening is larger, and, significantly enough, it
is still larger in the human foetus. When we examine some of the lower
mammals we discover the meaning of it. It is in them an additional
storage chamber in the alimentary system. It is believed that a change
to a more digestible diet has made this additional chamber superfluous
in the Primates, and the system is slowly suppressing it.

Other reminiscences of this earlier phase are found in the many
vestigial muscles which are found in the body to-day. The head of the
quadruped hangs forward, and is held by powerful muscles and ligaments
in the neck. We still have the shrunken remainder of this arrangement.
Other vestigial muscles are found in the forehead, the scalp, the
nose--many people can twitch the nostrils and the scalp--and under the
skin in many parts of the body. These are enfeebled remnants of the
muscular coat by which the quadruped twitches its skin, and drives
insects away. A less obvious feature is found by the anatomist in
certain blood-vessels of the trunk. As the blood flows vertically in a
biped and horizontally in a quadruped, the arrangement of the valves in
the blood-vessels should be different in the two cases; but it is the
same in us as in the quadruped. Another trace of the quadruped ancestor
is found in the baby. It walks "on all fours" so long, not merely from
weakness of the limbs, but because it has the spine of a quadruped.

A much more interesting fact, but one less easy to interpret, is that
the human male has, like the male ape, organs for suckling the young.
That there are real milk-glands, usually vestigial, underneath the teats
in the breast of the boy or the man is proved by the many known cases in
which men