practically certain that these cells meet in the oviduct, even in
that portion of it which receives the ovum just as it leaves the
ovary. Thither a number of the male cells have traveled by their own
activity; several come in contact with the ovum and one, but only
one, actually enters it. Almost at the moment when they touch, the
two cells unite so intimately that all trace of the spermatozoon is
lost. Fertilization of the ovum, as this event is scientifically
termed, has as its main purpose the uniting of the nucleus of a male
germinal cell with the nucleus of the female germinal cell. This
detail has been carefully studied; we know that the nuclei quickly
blend into one, and that the particles of living matter contributed
by the male animate the female cell with a new and wonderful
activity.

In our every-day way of speaking, fertilization means conception; it
is the instant in which a living being begins its existence. There is
no longer the slightest excuse for confusion regarding the period at
which the life of the unborn child begins. Before the significance of
fertilization was understood, it was perhaps not unreasonable to
believe that life began with quickening or about the time the fetal
heart-sounds could be heard. But now we must acknowledge that both
these ideas were incorrect. The animation of the ovum at the moment
of conception marks the beginning of growth and development which
constitutes its right to be considered as a human being.

Individuality, hereditary traits, sex--all these, we may be sure--are
unalterably determined from the moment of conception. The germinal
cell forms the total contribution of the male parent to pregnancy;
therefore no other opportunity for him to influence his progeny
presents itself, and the substance which enters the ovum at the time