Harmful as the practice of tight-lacing during pregnancy is, it does
not, thanks to the presence of the amniotic fluid, result in the
disfigurement of the child. For the same reason a blow struck upon
the abdomen, as in a fall forward, is not so serious as might be
thought, since the fluid, not the child, receives the force of the
impact. Some physicians believe that the fetus swallows the amniotic
fluid and thus secures nourishment. The fluid also serves to keep the
fetus warm; or, to be more exact, protects it from sudden changes in
the temperature of the mother's environment. Normally the temperature
of the fetus is thus kept nearly one degree higher than the
temperature of the parent.

Ultimately, the amniotic fluid assists in dilating the mouth of the
womb, which remains closed until the beginning of the process that
terminates with birth. The uterine contractions at the onset of labor
compress the fluid; in turn the fluid attempts to escape but is held
in check by the amniotic membrane, which it drives into the canal
leading from the uterine cavity to the vagina. Acting like a wedge,
the fluid gradually pushes the mouth of the womb wider and wider
open, until it is large enough for the child to pass. The sac usually
ruptures when that point is reached, the fluid escapes, and in due
time the child is born. This is followed within half an hour by the
extrusion of a mass of tissue--in reality the collapsed fetal sac--
which in every language, so far as I know, is named the After-Birth.
An examination of this tissue at the time of delivery repays the
physician, for it is important to ascertain that none of it has been
left in the uterus. Our interest at present, however, is to learn how
the after-birth has assisted toward the growth of the child.

THE PLACENTA.--The after-birth has puzzled scientists as well as the