ice on the part of the
parents and the stronger members of the race.

b. Sacrifice made consciously for the race is, in the natural order of
things, compensated.

CHAPTER II

ADOLESCENCE IN THE MALE

ADOLESCENCE IN THE MALE.

The period of a young man's life from about fifteen to twenty-five
years, when he is growing from boyhood to mature adult life, is called
the period of _adolescence_. The period of adolescence is ushered in
by a series of physical and psychical changes which make a well
defined initial period called _puberty_. The period of puberty is
about two years in length, and in the average case among American
boys, covers the period between the fifteenth and seventeenth years,
and is completed when the youth can produce fertile semen capable of
fertilizing the human ovum. It is now universally recognized, however,
that when the youth reaches this point in his development, while he
may be called a man, he represents manhood in its lowest terms. He has
not reached either a physical or mental development or maturity which
justifies him in undertaking the responsibilities incident to
procreating his kind. It requires in the average case a period of
eight more years to develop the young man to the full stature of adult
manhood, possessing his full physical and mental powers and the
strength required of one who should assume the responsibilities of
parenthood, so that at the age of twenty-five in the average case the
young man may be said to have reached this period of complete
development and to have finished the adolescent period. We may
profitably now consider more in detail some of the changes incident to
this most important period.

1. PHYSICAL CHANGES.

General Changes in the Body.

a. =Pilosity.=--The human being belongs to the vertebrate class,
mammalia, and as a member of that class he possesses over the
cutaneous surface of the body, excepting the palms of the hands and
soles of the feet, hair follicles which produce the hairy covering
typical of mammals. A careful study of the distribution of the hair on
the surface of the human body, comparing it with that of the
anthropoid apes, demonstrates that the distribution is identical; and
the "lay" of the hair in any one region of the human body corresponds
exactly with that of the same region in the ape. For example--the hair
on the forearm points outward and upward; on the upper arm down-ward
and outward and so on throughout in t