er has
satisfied himself of the fact by his own observation--that it does not
exceed the differences in the hair from different parts of the body of
the same individual. The human hair, like that of mammals in general,
consists of three tissues: an outer cortical layer, marked by
transverse striae, having in man the aspect of delicate lines, but in
many other animals assuming the character of distinct joints or
prominent serrations; a layer of elongated, fibrous cells, to which
the hair owes most of its tenacity; and an inner cylinder of rounded
cells. In the proportionate development of these several parts, in the
quantity of coloring matter present, and in the transverse section,
the human hair differs very considerably in different parts of the
body. It also differs very markedly in individuals of different
complexions. Similar but not greater differences obtain in the hair of
the scalp in different races; but the flatness of the Negro's hair
connects itself inseparably with the oval of the hair of the ordinary
European, and this with the round observed in some other races. It
generally holds that curled and frizzled hair is flatter than that
which is lank and straight; but this is not constant, for I have found
that the waved or frizzled hair of the New Hebrideans, intermediate
apparently between the Polynesians and Papuans, is nearly circular in
outline, and differs from European hair mainly in the greater
development of the fibrous structure and the intensity of the color.
Large series of comparisons are required; but those already made point
to variation rather than specific difference. Some facts also appear
to indicate very marked differences as occurring in the same race from
constant exposure or habitual covering; and also the occasional
appearance of the most abnormal forms, without apparent cause, in
individuals. The differences depending on greater or less abundance or
vigor of growth of the hair are obviously altogether trivial, when
compared with such examples as the hairless dogs of Chili and hairless
cattle of Brazil, or even with the differences in this respect
observed in individuals of the same race of men.

Confessedly the most important differences of the races of men are
those of the skeleton, in all parts of which variations of proportion
occur, and are of course more or less communicated to the muscular
investments. Of these, as they exist in the pelvis, limbs, etc., I
need say nothing; for, m