MENSTRUATION 
29 
tion which, pressing against the walls of the gland or duct, 
sets up a nerve excitation which gives rise to sex dreams and 
the resulting emission of semen. The boy who keeps his 
mind occupied with worthy things has nothing to fear. 
1. Why should occasional night emissions give a boy no concern? 
2. How can a boy avoid too frequent emissions? 
Menstruation. — Young women experience after puberty 
the periodic discharge of blood from the uterus, the menstrua¬ 
tion. It recurs at periods of about twenty-eight days and 
in health lasts from three to five days. The bleeding is 
caused by some of the lining cells of the uterus breaking 
down and exposing the very small blood vessels, which are 
easily ruptured. The muscular contractions of the uterus 
check the bleeding, and new cells soon replace those broken 
down. The purpose of this function probably is to prepare 
a fresh surface for the attachment of the egg. Although a 
mature egg may be discharged from the ovary at other times, 
this process ( ovulation ) usually occurs just before menstrua¬ 
tion. Hence it is that conception usually occurs at this time. 
If a girl is normal, she should not baby herself by going to 
bed or sitting in an easy chair for a day or two during her 
period; she should be able to continue her usual work, but 
should, avoid any unusual strain or fatigue. Wet feet or chill¬ 
ing is to be guarded against. Exercise is desirable but should 
be somewhat moderated. Clothing should be loose and easy; 
and the pressure of all stays, bands or straps, straight fronts, 
and hip reducers is more than ever harmful at this time. If 
a girl would bear this function easily and later become a good 
mother, she must be a good animal; she must do more walk¬ 
ing, rowing, swimming, and play more open-air games than 
has in the past been customary with girls, but not during 
menstruation. During her period a healthy girl should 
bathe daily, but should be careful that the water is not so 
cold or the bath so prolonged as to chill her. 
