COKPF8 LUTEUM. 307 



different elements entering into the structure of the mucous 

 membrane, including the blood-vessels, this change being 

 most marked at the surface ; and it is on account of the 

 weakened condition of the vascular walls that the hsemor- 

 rhage takes place. A short time after the flow has ceased, 

 the mucous membrane returns to its ordinary condition. 1 



We have already noted that there is a considerable des- 

 quamation of epithelium from the uterus with the flow of 

 blood, during the menstrual period. Sometimes, in normal 

 menstruation, the epithelium is in the form of patches ; and, 

 in certain cases of dysmenorrhea, there is a membranous ex- 

 foliation, which has led to the idea that the mucous mem- 

 brane is actually thrown off. In normal menstruation, there 

 is no true exfoliation of the membrane, and, even in what is 

 called membranous dysmenorrhea, the so-called membrane is 

 usually nothing more than a membraniform exudation, se- 

 creted by the mucous surface. 



Changes in the Graafian Follicles after their Rupture 

 (Corpus Luteum). After the discharge of an ovum, the 

 Graafian follicle undergoes certain retrograde changes, in- 

 volving the formation of what is called the corpus luteum. 

 Even when the discharged ovum has not been fecundated, 

 the corpus luteum persists for several weeks, so that, ovula- 

 tion occurring every month, several of these bodies, in various 

 stages of retrogression, may sometimes be seen in the ovaries. 

 Corpora lutea were observed by some of the earliest writers 

 upon anatomy ; but the first description presenting any ap- 



1 KUNDRAT UND ENGELMAXN, Untersuchungen uber die Uterusschleimhaut. 

 Medicinische Jahrbucher, Wien, 1873, S. 135, et seq. 



The researches embodied in the above paper are of great importance in their 

 bearing upon the physiology of menstruation, the preparation of the mucous 

 membrane of the uterus for the reception of the fecundated ovum, and calcula- 

 tions of the duration of pregnancy. From the facts and arguments brought for- 

 ward, there can be scarcely a doubt that the flow of blood is mainly due to fatty 

 degeneration of the most superficial portion of the mucous membrane. The 

 points in these observations which relate to the question of the preparation of 

 the uterus for the reception of the ovum will be considered hereafter. 



