76 



THE PHYSIOLOGY OF REPRODUCTION 



by cell division, partly (aiccording to Engelmann^) by an increase 

 in intercellular substance, and partly by an enlargement of tbe 

 glands and blood-vessels. According to Lipes,^ this stage commences 

 as soon as the process of regeneration (following the preceding 



Fig. 7. — Section through wall of vagina (lower part) of monkey. 



a, Epithelium lining cavity ; b, sub-mucous layer ; c, muscular layer ; 

 d, d', nerve ganglia ; e, artery ; /, fat cells. 



menstrual period) is completed, which is about eighteen days after 

 the cessation of the previous flow. " During the stage of regenera- 



1 Engelmann, "The Mucous Membrane of the Uterus, etc.," Amer. Jour. 

 Obstet., vol. viii., 1875. 



2 Lipes, "A Study of the Changes occurring in the Endometrium during 

 the Menstrual Cycle," Albany Medical Annals, vol. xxv., 1904 



