of
menstruation is its regular return about every twenty-eight days. The
menstrual flow usually continues from three to six days, and the
discharge seems to be ordinary blood, which, during its vaginal passage,
becomes mixed with mucus, and is thereby deprived of the power of
coagulation. The quantity exuded varies from two to eight ounces, but
the amount consistent with the health of one person, may be excessive
and weakening in another. This function is regarded as "being regular
when its effect upon the system is favorable, for whatever organic
process directly contributes to the health should be considered as
normal. It occurs at regular intervals for about thirty years, when
menstruation and the aptitude for conception simultaneously cease.

The departures from healthy menstruation are numerous. The most
important of these are _amenorrhea, dysmenorrhea_, and _menorrhagia_.

AMENORRHEA.

The term _amenorrhea_ signifies the absence of menstruation when it
should occur. It may be considered under two general heads: when it
fails to be established at the proper age, and when, after having made
its appearance, it ceases to return at the usual periods. The term
_retention_ has been applied to the first, and that of _suppression_ to
the latter. Menstruation may fail to be established in consequence of
organic defects, or from some abnormal condition of the blood and
nervous system.

MALFORMATION OF THE VAGINA. Retention of the menses may result from
malformation of the vaginal canal, which sometimes terminates before it
reaches the womb, being simply a short, closed sac. If the uterus and
ovaries are perfect, all the feminine characteristics are manifest, and
a vaginal exploration discloses the nature of the difficulty. If,
however, the sides of this passage adhere in consequence of previous
inflammation, they may be carefully separated by a surgical operation,
and this function restored.

ABSENCE OR MALFORMATION OF THE WOMB. The uterus may be deformed or
entirely absent, and yet there be an inclination, or symptoms indicative
of an effort, to establish this function. The individual may be delicate
in organization, graceful in bearing, refined and attractive in all
feminine ways, and yet this organ may be so defective as to preclude the
establishment of the menstrual function. Sometimes there is merely an
occlusion of the _mouth_ of the uterus, the perforation of which removes
all difficulty. In others, the _nec