a. For
instance, it is entirely absent in all the chimpanzees, which I have
examined, while scantily present in all the orangs. As in man, it occurs
in a patch midway between the joints.

[Illustration: FIG. 23.--Hair-tracts on the arms and hands of Man,
as compared with those on the arms and hands of Chimpanzee. Drawn
from life.]

Besides showing these two features with regard to the disposition of
hair on the human arm and hand, the above woodcut illustrates a third.
By looking closely at the arm of the very hairy man from whom the
drawing was taken, it could be seen that there was a strong tendency
towards a whorled arrangement of the hairs on the backs of the wrists.
This is likewise, as a general rule, a marked feature in the arrangement
of hair on the same places in the gorilla, orang, and chimpanzee. In the
specimen of the latter, however, from which the drawing was taken, this
characteristic was not well marked. The downward direction of the hair
on the backs of the hands is exactly the same in man as it is in all
the anthropoid apes. Again, with regard to hair, Darwin notices that
occasionally there appears in man a few hairs in the eyebrows much
longer than the others; and that they seem to be representative of
similarly long and scattered hairs which occur in the chimpanzee,
macacus, and baboons.

Lastly, it may be here more conveniently observed than in the next
chapter on Embryology, that at about the sixth month the human foetus
is often thickly coated with somewhat long dark hair over the entire
body, except the soles of the feet and palms of the hands, which are
likewise bare in all quadrumanous animals. This covering, which is
called the lanugo, and sometimes extends even to the whole forehead,
ears, and face, is shed before birth. So that it appears to be useless
for any purpose other than that of emphatically declaring man a child of
the monkey.

(9) _Teeth._--Darwin writes:--

It appears as if the posterior molar or wisdom-teeth were tending
to become rudimentary in the more civilized races of man. These
teeth are rather smaller than the other molars, as is likewise the
case with the corresponding teeth in the chimpanzee and orang; and
they have only two separate fangs.... They are also much more
liable to vary, both in structure and in the period of their
development, than the other teeth. In the Melanian races, on the
other hand, the wisdom