REPRODUCTION 517 



Hygiene of Menstruation. During menstruation there is apt to 

 be more or less general discomfort and nervous irritability; the 

 woman is not quite herself, and those responsible for her happiness 

 ought to watch and tend her with special solicitude, forbearance, 

 and tenderness, and protect her from anxiety and agitation. Any 

 strong emotion, especially of a disagreeable character, is apt to 

 check the flow, and this is always liable to be followed by serious 

 consequences. A sudden chill often has the same effect; hence a 

 menstruating woman ought always to be warmly clad, and take 

 more than usual care to avoid draughts or getting wet. At these 

 periods, also, the uterus is enlarged and heavy, and being (as may 

 be seen in Fig. 152) but slightly supported, and that near its lower 

 end, it is especially apt to be displaced or distorted; it may tilt 

 forwards or sideways (versions of the uterus,) or be bent where the 

 neck and body of the organ meet (flexion) . Hence violent exercise 

 at this time should be avoided, though there is no reason why a 

 properly clad woman should not take her usual daily walk. 



The absence of the menstrual flow (amenorrhea) is normal dur- 

 ing pregnancy and while suckling; and in some rare cases it never 

 occurs throughout life, even in healthy women capable of child- 

 bearing. Usually, however, the non-appearance of the menses at 

 the proper periods is a serious symptom, and one which calls for 

 prompt measures. In all such cases it cannot be too strongly im- 

 pressed upon women that the most dangerous thing to do is to take 

 drugs tending to induce the discharge, except under skilled ad- 

 vice; to excite the flow, in many cases, as for example occlusion of 

 the os uteri, or in general debility (when its absence is a conserva- 

 tive effort of the system), may have the most disastrous results. 



Fertilization. As the ovum descends the Fallopian tube the 

 changes of menstruation are taking place in the uterus. Fertiliza- 

 tion usually takes place in a Fallopian tube. The spermatozoa are 

 carried along partly, perhaps, by the contractions of the muscular 

 walls of the female cavities, but mainly by their own activity. 

 Occasionally the ovum is fertilized before reaching the Fallopian 

 tube and fails to enter it, giving rise to an extra-uterine pregnancy. 



The actual process of the fertilization of the ovum has only been 

 observed in the lower animals, but there is no doubt that the phe- 

 nomena are the same in all essentials in all cases. Some of the 

 spermatozoa penetrate the zona pellucida and the head of one of 



