ANATOMY OF THE FOWL 



43 



sule ruptures and the yolk falls into an expanded portion of 

 the oviduct at c, Fig. 13. This portion of the duct is very 

 thin and gradually merges into a thicker wall, in which i)or- 

 tion the mucous membrane is thrown into folds. The yolk is 

 surrounded by a delicate membrane, the vitelline membrane, 

 which holds the mass intact, thus giving it the spherical ap 

 pearance. 



After the stigmen ruptures and the yolk is discharged into 





Fig. 13. Pelvic Organs of a Hen. 

 a, the ovary; b, ovum fully developed; c, infundibulifomi portion of the oviduct; 

 d, stigma or" point of rupture of follicle; e, a degenerated ovum; f, portion in 

 which shell is formed; g, a portion of the oviduct torn from its ligaments and laid 

 over to one side: h, showing th.e villus-like mucous membrane; i, albuminous 

 portion of newly formed egg; j, the yolk of the same; k, rectum; 1, cloaca. 



the Q^^ canal there remains a cup-shaped cavity attached to 

 the ovary and which is called the calyx, which gradually dis- 

 appears. 



One by one the yolks are developed to full size or to ma- 

 tui'ity from the mass of undeveloped ova of the ovary as illus- 

 trated in Fig. 12, letter a. Fig. 13, letter 1), shows an ovum or 

 yolk reaching full development, and d shows a non-vascular 



