THE URO-GENITAL SYSTEM 



179 



active state are developed, one by one, into yolks with their blasto-- 

 derms. From the blastoderm the fetus may later be developed. 

 In the active ovary of the laying hen the ovarian mass is of consider- 

 able size, as it contains ova in different stages of development. 

 Only one ovum is completely developed at a time, though occasion- 

 ally there may be only a few hours between the maturity of succes- 



FiG. 56. — Functionating female generative organs of a hen. i , Ova in process 

 of formation of yolk. 2, Stigmal line at -which point the capsule ruptures when 

 ovum is mature. 3, The funnel end of the oviduct. 4, The oviduct torn loose 

 and laid to one side, the albumin-secreting portion. 5, The shell membrane 

 secreting portion. 6, The albumin. 7, The yolk. 8, The shell-secreting por- 

 tion. 9, The cloaca. 10, The rectum. 



sive ova. The ova receives nourishment from the blood-vessels 

 of the capsule, which vessels are branches of the ovarian artery. 



Structure. — The ovary contains very vascular cellulofibrous tissue. 

 The ovum as it develops is attached to the ovarian body by means 

 of a delicate white fibrous pedicle. When the yolk is mature 

 it escapes from the enveloping fibrous capsule by a cleavage of 

 the" capsule. The cleavage line is called the stigmen (Fig. 56, No. 



