neighborhood of each ovary; both enter the uterus, but on opposite
sides. The ovum travels down the tube which corresponds to the ovary
where it originated. The journey is fraught with momentous
consequences, for it is during this passage through the oviduct that
the fate of the ovum is determined. If it is to develop into a living
creature, a great many conditions must sooner or later be fulfilled;
but there is one which must be promptly satisfied. Shortly after
leaving the ovary the ovum must receive the stimulus to live and
grow; otherwise it will quickly wither and die. This vital stimulus
can be imparted only by the spermatozoon.

The male germinal cell is like the female cell in the possession of a
nucleus; in other respects it is very different. Longer but much
narrower than the ovum, the tiny arrow-shaped spermatozoon is
particularly distinguished by its active motility, for it has a tail
that propels it. The human male cell must travel some distance to
reach the point where it can meet a ripe and vigorous ovum; and since
the journey is not without danger to its life, Nature has provided
that exceedingly large numbers of the male cells shall be deposited
in the vagina at the time of the marital relation. In this way, it is
made sure that some of them will travel up through the uterus and
oviducts, arriving in the neighborhood of the ovaries.

FERTILIZATION.--Convincing observations upon the lower forms of life,
especially upon fishes, have shown that when the germinal cells come
near to each other, the ovum attracts the spermatozoon. The power of
attraction which the ovum exerts may be likened, most simply, to the
influence of a magnet upon iron-filings. While there has been no
opportunity to observe such attraction between the parent cells of
human beings, its existence is not open to doubt. And it is