670 MENSTRUATION. [BOOK iv. 



slowly, by the action probably of the cilia lining the tube, though 

 possibly its progress may occasionally be assisted by the peristaltic 

 contractions of the muscular walls. The stay of the ovum in the 

 Fallopian tube may extend to several days. There is an effusion of 

 blood into the ruptured follicle, which is subsequently followed by 

 histological changes in the coats of the follicle resulting in a corpus 

 luteum. The discharge of the ovum is accompanied not only by a 

 congestion or erection of the ovary and Fallopian tube, but also by 

 marked changes in the uterus, especially in the uterine mucous 

 membrane. While the whole organ becomes congested and en- 

 larged, the mucous membrane, and especially the uterine glands, 

 are distinctly hypertrophied. The swollen internal surface is 

 thrown into folds which almost obliterate the cavity ; and a 

 h^emorrhagic discharge, often considerable in extent, constituting 

 the menstrual or catamenial flow, takes place from the greater 

 part of its surface. The blood as it passes through the vagina 

 becomes somewhat altered by the acid secretions of that passage, 

 and when scanty coagulates but slightly ; when the flow however is 

 considerable, distinct clots may make their appearance. The 

 swollen and hypertrophied mucous membrane then undergoes a 

 rapid degeneration, and is shed, passing away sometimes in distinct 

 masses, forming the latter part of the menstrual flow. The loss of 

 the mucous membrane is so complete, that the bases only of the 

 uterine glands are left, and from the epithelial cells lining these 

 the regeneration of the new membrane is said to take place. It is 

 not certain that menstruation, in the human subject at all events, 

 is always accompanied by a discharge of an ovum ; indeed cases 

 have been recorded in which menstruation continued after what 

 appeared to be complete removal of both ovaries. And it seems 

 probable also that under certain circumstances, ex. gr. coitus, a dis- 

 charge of an ovum may take place at other times than at the 

 menstrual period. Since however the time during which both the 

 ovum and the spermatozoon may remain in the female passages 

 alive and functionally capable is considerable, probably extending 

 to some days, coitus effected either some time after or some time 

 before the menstrual escape of an ovum might lead to impregna- 

 tion and subsequent development of an embryo; hence the fact 

 that impregnation may follow upon coitus at some time after or 

 before menstruation is no very cogent argument in favour of the 

 view that such a coitus has caused an independent escape of an 

 ovum. The escape of the Ovum is said to precede, rather than 

 coincide with or follow, the catamenial flow. If no spermatozoa 

 come in contact with the ovum it dies, the uterine membrane 

 returns to its normal condition, and no trace of the discharge of an 

 ovum is left, except the corpus luteum in the ovary. 



It is obvious that in these phenomena of menstruation we have 

 to deal with complicated reflex actions affecting not only the 

 vascular supply but, apparently in a direct manner, the nutritive 



