181 



93.] The Menstruation of Semnopithecus entellus. 171 



Stage V. The extravasated blood now collects into lacunae which 

 are first formed within the stroma but gradually extend superficially, 

 displace the intervening stroma elements and lie directly in contact 

 with the epithelium. 



The vessels in the deeper mucosa remain intact; there is no trace 

 of diapedesis and no red blood corpuscles or leucocytes in the stroma 

 in this region. 



Stage VI. The lacunse increase in size. The uterine epithelium, 

 and superficial stroma shrivel up and exhibit signs of degeneration. 

 The epithelium ruptures and the blood contained in the lacunae is 

 poured into the uterine cavity. 



Stage VII. Denudation follows. All the uterine epithelium, a 

 portion of the glands and in some places a whole gland, and a depth 

 of about one-third of the layer of the stroma is cast away, together 

 with ruptured vessels, red blood corpuscles and leucocytes. Of these 

 substances the menstrual clot is formed. 



This is a severe, devastating, periodic action which is very re- 

 markable. 



A ragged surface is left behind and the remaining stroma contains, 

 at or near the surface, masses of extravasated blood. In the deeper 

 parts of the mucosa there is no further change. 



Period D. 



Stage VIII. The recuperation consists of the re-formation of the 

 epithelium, partly from the torn edges of the glands and partly by 

 means of the transformation of stroma elements into flat epithelium ; 

 of the formation of new capillaries in the superficial region out of 

 the stroma cells which surround the intercellular spaces in which the 

 extravasated blood lies, and in the return of this reclaimed blood to 

 the circulatory system; of the return of the vessels in the deeper 

 mucosa to their normal size and consistency, and of the return of the 

 stroma to the condition of rest (Stage I). 



The new epithelium, at first flattened, becomes cubical, and new 

 glands are formed from folds of this epithelium. 



The numerous leucocytes left with the extravasated blood are 

 returned to the circulatory system with the latter ; they do not 

 migrate, they do not form new tissue in situ or pus on the wounded 

 surface. 



Ovulation. 



Out of the ovaries of forty-two specimens of menstruating S. entel- 

 lus only two were found in which recent discharged follicles were 

 seen. Such a result appears to be sufficient to warrant the state- 

 ment that 



