MENSTRUATION. 573 



The process of ovulation, accordingly, in the human female, 

 accompanies and forms a part of that of menstruation. As the 

 menstrual period comes on, a congestion takes place in nearly the 

 whole of the generative apparatus ; in the Fallopian tubes and the 

 uterus, as well as in the ovaries and their contents. One of the 

 Graafian follicles is more especially the seat of an unusual vascular 

 excitement. It becomes distended by the fluid which accumulates 

 in its cavity, projects from the surface of the ovary, and is finally 

 ruptured in the same manner as we have already described this 

 process taking place in the lower animals. 



It is not quite certain at what particular period of the menstrual 

 flow the rupture of the vesicle and discharge of the egg take place. 

 It is the opinion of Bischoff, Pouchet, and Kaciborski, that the 

 regular time for this rupture and discharge is not at the commence- 

 ment, but towards the termination of the period. Coste 1 has ascer- 

 tained, from his observations, that the vesicle ruptures sometimes 

 in the early part of the menstrual epoch, and sometimes later. . So 

 far as we can learn, therefore, the precise period of the discharge 

 of the egg is not invariable. Like the menses themselves, it may 

 apparently take place a little earlier, or a little later, accoi'ding to 

 various accidental circumstances ; but it always occurs at some 

 time in connection with the menstrual flow, and constitutes the 

 most essential and important part of the catamenial process. 



The egg, when discharged from the ovary, enters the fimbriated 

 extremity of the Fallopian tube, and commences its passage toward 

 the uterus. The mechanism by which it finds its way into and 

 through the Fallopian tube is different, in the quadrupeds and the 

 human species, and in birds and reptiles. In the latter, the bulk 

 of the egg or mass of eggs discharged is so great as to fill entirely 

 the wide extremity of the oviduct, and they are afterward conveyed 

 downward by the peristaltic action of the muscular coat of this 

 canal. In the higher classes, on the contrary, the egg is micro- 

 scopic in size, and would be liable to be lost, were there not some 

 further provision for its safety. The wide extremity of the Fallo- 

 pian tube, accordingly, which is here directed toward the ovary, is 

 lined with ciliated epithelium; and the movement of the cilia, 

 which is directed from the ovary toward the uterus, produces a 

 kind of converging stream, or vortex, by which the egg is neces- 

 sarily drawn toward the narrow portion of the tube, and subse- 

 quently conducted to the cavity of the uterus. 



1 Loc cit. 



