32 



in the characterpf the cy^orlasT, It loses its horrogene- 



er 

 ous and finely f^ranular nature and develo::3 a suT^nly of deut^o- 



clasTn in the fort of yolk granules. These are large and stain 



very darkly. They first aorear around the gerrinal vesicle. 



As they be3o;r:e more nuinerous by the continual formation of 



new ones, they are oushed out through the cytC'lasr toward 



the ^.eri-hery. The formation of the yolk ST)heres goes on until 



the ovum is densely crowded v/ith thea exceot for a narrow 



Derioherl zone, in v/hich the proto'^las" retains its honno- 



geneous and finely granular character and forTS the ectonlasn^ 



of the -rature egg. Figures 1 tc 6 inclusive show different 



stages in the develCTent of the ovarian egg and the forn^ation 



and 'Tiigration of the yolk granules. Soine idea of the extent 



to which the ijrotoolas'n becoTies crowded with s'oheres of 



deutonlas" can be forned fron Figure 3, which is drawn fron 



a nearly nature ovum. In the fully develoned egg the layfr 



of ectonlasT is narrower than is ronresented in this figure. 



The yolk granules first arj:";ear around the nucleus of the 



