CHAP XL.] 



GENERATION, 

 Fig. 271. 



575 



A perfectly mature ovum from the ovary, showing the spin- 

 dle-shape which the cells of the discus proligerus have assumed. 



The same ovum with the cells 

 of the discus pro ligems removed. 

 The germinal vesicle has disap- 



An ovum from the upper third of the 

 ovary. The yolk does not completely fill 

 the cavity of the zona pellucida. Between 

 it and the zona is seen a clear transparent 

 body, distinct from it. Rotation of the yolk 

 was visible in this ovum. 



An ovum from the middle of the ovary. 

 The yolk is divided into two masses. Two 

 clear vesicles are seen between it and the 

 zona. A spermatozoon is observed upon 

 the zona pellucida. 



! 



The yolk diviJed into four portions. 

 This ovum was takeii from the lower third 

 of the ovary. 



An ovum from the upper part of the 

 uterus, four days old. The segmentation of 

 the yolk has proceeded still farther. 



