man and woman, the human race has been
perpetuated by a series of births. Children have been conceived in
harmony with the natural order of events, in such matters, and have been
born boys and girls. A boy is a boy to all intents and purposes from his
very conception, from the very earliest moment of his being; begotten by
his father he is a boy in embryo within the ovule of his mother. The
converse is true of the opposite sex. At this very early age of
reproduction the embryo has all the elements of the future man or
woman, mentally and physically, even before any form becomes apparent;
and so small is the human being at the earliest stage of its existence
that no material change is observable between the ovule that contains
the product of conception and a fully developed ovule unimpregnated.[A]

[A] For fuller particulars see Guernsey's Obstetrics, 3d edition,
pages 79-89, inclusive.

It is about twelve days after conception before the impregnated ovule,
which undergoes many changes during this time, makes its escape from the
ovary where it became impregnated and enters one of the Fallopian tubes,
thence gradually descending into the cavity of the womb. Here it begins
to mature and become fitted for its birth into the outer world. Soon now
the embryo (for such it is called at this early stage) begins to assume
form. The first indication of formation that it is possible to discover,
even by the help of the microscope, consists of an oblong figure, obtuse
at one extremity, swollen in the middle, blunt-pointed at the other
extremity. The rudimentary embryo is slightly curved forward, is of a
grayish white color, of a gelatinous consistence, from two to four lines
long and weighs one or two grains. A slight depression representing the
neck, enables us to distinguish the head; the body is marked by a
swollen centre, but there are as yet no traces of the extremities. So
much can be observed about the end of the third week after conception.

At about the _fifth week_ the embryo presents more distinctions. The
head is very large in proportion to the rest of the body, the eyes are
represented by two black spots, and the upper extremities by small
protuberances on the sides of the trunk. The embryo at this stage is
nearly two-thirds of an inch in length and weighs about fifteen grains.
The lower extremities now begin to appear in the shape of two minute
rounded tubercles. Till about this time a straight artery has been
o