THE VILLI OF THE CHORIOK 



753 



at length form the minute extremities of the blood-vessels 



which are, so to speak, conducted from the foetus to the 



chorion by the allantois (fig. 219). The function of the 



Fig. 219.* 



villi of the chorion is evidently the absorption of nutrient 



* Fig. 219 represents a perpendicular section of a uterus, with a fully 

 formed ovum. A plug of lymph (i) occupies the cervix uteri; 2, indi- 

 cates the opening of the Fallopian tube on one side ; 3, the decidua vera ; 

 4, the cavity of the uterus nearly filled by the ovum ; 5, the decidua 

 reflexa ; 6, the chorion ; 7, the decidua serotina (see p. 756) ; 8, the 

 allantois and the situation of the future placenta ; 9, the amnion ; 10, 

 the umbilical vesicle ; n, the umbilical cord. 



3 



