THE FEMALE ORGANS OF GENERATION. 



249 



lum of fine fibrils. Within the vitellus is seen the nucleus or 

 germinal vesicle (also presenting a delicate reticulum of fibrils), 

 situated eccentrically, spherical in shape, measures 0.037 to 

 0.451 mm. in diameter, shining, transparent, and contains the 

 nucleolus or germinal spot, which is a highly refractile body, 

 finely granular, supposed to be non-vesicular, and measures 

 0.0046 to 0.0068 mm. in diameter. 



The mature Gfraafian follicle, which is seen on the surface 



FIG. 108. 4, primordial egg of the human being ; 8 months 1 fcetus. B, primordial follicle of the 

 rabbit. <7, primordial follicle of a dove. D, a somewhat older follicle of the same animal ; commence- 

 ment of the formation of the subordinate yolk. E, blind end of the ovary of an ascaris nigrovenosa ; 

 germinal vesicles (some of which possess a germinal spot and Schron's ''granule") in a diffuse mass of 

 protoplasm. F, egg of the ascaris nigrovenosa from about the middle of the ovary ; Schron's granule ; 

 commencement of the deposition of yolk-matter. <?, egg from a follicle (2 mm. in diam.) of the rabbit : 

 a. egg-epithelium; &, striated zone with radiating striae ; c, germinal vesicle; d, germinal spot ; e, yolk. 



of the ovary, giving rise to a prominence, ruptures during the 

 menstrual period and empties its contents, viz. : the ovum, 

 fluid contents, and discus proligerus into the Fallopian tube. 

 The cause of the rupture is an increase in the contents of the 

 follicle, and a fatty metamorphosis of the cells of the wall of 

 the follicle. As a result of this rupture of the Gfraafian vesi- 

 cle, there is formed a yellow body, the corpus luteum, which 



