THE OVIDUCT 



301 



network of fine blood vessels. The upper opening of the oviduct 

 is expanded in the shape of a funnel to facilitate the entrance 

 of the ovum when it emerges from the yolk sac. The duct on its 



Calyx orjrolk sack 



Lei-st portion ofduot I 

 opened, showing f 

 completed 



Yolk 

 /Itrtnel- 



Second, 



of the 



where the silbumirt, 



zVs formed 



Third, portion where 

 \ the >shell is added 



which the 

 z\y expelled 



Vent or clo&ca 

 FIG. 145. Female reproductive organs. 



way to the cloaca lies in folds, being lapped upon itself three times 

 before it finally passes into the cloaca. 



When the yolk enters the oviduct it consists of a yellow mass, 

 called the " vitellus," enclosed in a thin membrane, the " vitelline " 

 membrane. Fertilization takes place in the upper part of the ovi- 

 duct before any albumin has been added, and if at this time the 



