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 developmentr 

 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. 



