CESTROUS CYCLE IN THE GUINEA-PIG. 233 



welche zum Teil aus verdichtetem Schleim, zum Teil aus Epithel- 

 zellen bestanden. Unter diesen Verhaltnissen 1st die Bedeutung 

 des Vaginalpfropfs beim Meerschweinchen ganz nichtig, und am 

 Anfange meiner Arbeit habe ich, durch diese Angabe Bischoff's 

 irregefiihrt, einige Tiere verloren, weil sie zu spat getotet wurden. 

 . Konigstein ('07) described the vaginal plug in rats and agrees 

 with the observations of Lataste, Tafani and Sobotta. He finds 

 also the vaginal plug to consist of two parts, a central and a 

 superficial. The vaginal plug contains in addition to the secre- 

 tions of the male genital glands, mucus, detritus, many leucocytes, 

 squamous epithelial cells in large numbers and a granular eosin- 

 phil staining secretion. 



From this review the knowledge of the formation of the 

 vaginal plug is found to be rather complete, although disagree- 

 ments as to facts are expressed by several authors. It seems 

 well established that the formation of a vaginal plug following 

 copulation is a general phenomenon among the various species 

 of rodents. The plug proper consists of a central core formed 

 mainly by coagulated fluid from the seminal vesicles and this 

 is surrounded or enclosed by a mass of flat epithelial cells, 

 apparently derived from the vaginal wall. The coagulation of 

 the seminal fluid may be due to the action of a prostatic enzyme 

 although it is claimed that the coagulation occurs without the 

 presence of such an enzyme. The vaginal plug as a whole 

 falls out of the vagina a few hours after its formation. 



On the other hand it is not clear from the literature just 

 how or why the peripheral part of the vaginal plug, enveloppe 

 vaginale, of Lataste is formed. And the manner and cause of 

 the separation of the epithelial lining from the wall of the vagina 

 are also unknown. These points could not be clearly understood 

 without a knowledge of the changes occurring in the wall of the 

 vagina and uterus during the oestrus, at which time copulation 

 and the formation of the vaginal plug take place. 



As we pointed out in our description of the cestrous changes, 

 there is a stage in the cycle when immense numbers of leucocytes 

 accumulate immediately below the epithelium lining the uterus 

 and the vagina. From this position the leucocytes attack the 

 epithelial cells and at the same time dissolve or destroy the 



