1 120 REPRODUCTION 



lashing cilia which line it. Probably the ovum takes as a rule eight 

 or ten days to reach the uterus, and it is during this time that 

 fertilization takes place. If not impregnated, it soon perishes amid 

 the secretions of the uterus how soon has been matter of discussion, 

 and can hardly be considered as settled. If, however, impregnation 

 occurs, the ovum penetrating the superficial epithelium into the 

 subepithelial connective tissue becomes fixed in one of the crypts or 

 pouches of the uterine mucous membrane (cLecid.ua serotina), which 

 grows round it as the decidua reflexa. The Graafian follicle, after 

 the discharge of the ovum, fills up with blood, and a cellular struc- 

 ture, the corpus luteum, is developed in its interior from cells in 

 the wall of the follicle. In the absence of impregnation the corpus 

 luteum begins to disappear before the next menstrual period, and is 

 spoken of as a false corpus luteum. But when pregnancy occurs, it 

 continues to grow till the fourth or fifth month of pregnancy, and is 

 called a true corpus luteum. 



Menstruation. In the mature female, from puberty, the age at 

 which the reproductive power begins (thirteenth to fifteenth year), 

 on till the time of the menopause (fortieth to fiftieth year) , at which 

 it ceases, an ovum or it may be in some cases more than one is 

 discharged at regular intervals of about four weeks. This discharge 

 is accompanied by certain constitutional symptoms and local signs 

 that last for a variable number of days. The temperature of the 

 body diminishes somewhat, rarely more th.in i F., and there is 

 also a slight fall in the pulse-rate. The genit;i I organs are congested, 

 and a quantity of blood, which varies in different individuals, but 

 is usually not over 50 c.c., is shed. If more than 60 c.c. is lost, the 

 flow is copious. Over 100 c.c. it is abnormally great (G. Hoppe- 

 Seyler). At the same time, the whole or a portion of the mucous 

 membrane of the uterus is cast off. 



As to the physiological meaning of this menstruation, as it is 

 called, opinion is divided. Two chief theories have been proposed 

 to account for it, both of which agree in considering the phenomenon 

 to be connected with a preparation of the uterus for the reception 

 of the ovum. But according to the theory of Pfliiger, the mucous 

 membrane is stripped off (by a process analogous to the ' f eshening ' 

 or paring of the indurated edges of a wound by the surgeon, in 

 order that union may occur when they are brought together) on 

 the chance, so to speak, that an impregnated ovum may arrive. On the 

 alternative theory, this change takes place because the ovum has not 

 been impregnated, and the bed prepared for it not being required, 

 the swollen and congested uterine mucous membrane undergoes 

 degeneration, and is in part cast off (Reichert, Williams, etc.). 

 However this may be, it is now pretty generally agreed that the 

 degenerative process involves only the superficial portion of the 

 mucosa, and not its whole thickness. 



