be when the spermatozooen meets it, as
is usually the case, it travels down to the uterus, and fixes itself
there.

=Extra-Uterine Pregnancy.= The tube is a bad place for the ovum to
grow and develop, because the tube cannot stretch to such an extent as
the uterus can, nor can it furnish the embryo such good nourishment as
the uterus can. Occasionally, however, it happens that the impregnated
ovum remains in the tube and develops there; we then have a case of
what we call _extra-uterine_ (outside-of-the-uterus) or _tubal_
pregnancy. Extra-uterine pregnancy is also called _ectopic_ pregnancy,
or ectopic gestation. Unless diagnosed early and operated upon, the
woman may be in great danger, for after a few weeks or months the tube
generally ruptures.

From the moment the spermatozooen has entered the ovum, a process of
_division_ or _segmentation_ commences. The ovum, which consists of
one cell, divides into two, the two into four, the four into eight,
the eight into sixteen, these into thirty-two, these into sixty-four,
128, 256, 512, 1,024, until they can no longer be counted. This
mulberry mass of cells arranges itself into two layers, with a cavity
in between. And from these layers of cells there develop gradually all
organs and tissues, until a fully formed and perfect child is the
result. If two ova are impregnated at the same time by two
spermatozoa, the result is twins.[5]

I might mention here that the moment the ovum is impregnated, i.e.,
joined by a spermatozooen, it is called technically a zygote; it is
also called embryo, and this name is applied to it until the age of
five or six weeks. Some use the term embryo up to two or three months.
After that, until it is born, it is called fetus.

A study of the development of the embryo and the formation of the
various organs from one single cell, the ovum, vitalized or fecundated
by another single cell, the spermatozooen, is the most wonderful and
most fascinating of all studies. But that belongs to the domain of
Embryology, which is a separate science.

What we see in the process of fecundation is a foreshadowing of the
future man and woman. The ovum has no motion of its own, it is moved
along by the wave-like motions of the lining cells of the Fallopian
tube, and throughout the entire act it remains passive. The
spermatozooen, on the other hand, is in a state of continuous activity
from the moment it has been ejaculated by the male until it has
reached its g