282 GEORGE W. BARTELMEZ 



only evidences of activity between hatching and maturity are the 

 growth to a maximum of 0.09 mm., and the accumulation of the 

 deutoplasm of the spherule cap. When a primordial follicle 

 begins to grow, however, striking changes occur in the germinal 

 vesicle and the ooplasm. The chromosomes lose their thickened 

 form, become more finely granular and longer, so that they stain 

 more lightly, and many nucleoli are formed apparently at theii' 

 expense (figs. 10, 13, 14, 15, 16, 18). In the ooplasm more spher- 

 ules are laid down so that the peripheral zone becomes narrower, 

 (figs. 13 and 17), and there is a marked increase in the yolk nucleus 

 material (chromidial substance?), due largely, as D'Hollander ('04) 

 and others have contended, to a transfusion of chromatin through 

 the nuclear membrane; the striking observations of Munson ('04) 

 are of especial interest- in this connection. Figure 14 shows the 

 increase of the yolk nucleus in an oocyte at the beginning of the 

 second growth period. Figure 17 shows the yolk spherules at 

 this stage; it was taken from a free hand section stained with 

 Sudan iii. The red stained spherules (black in the photograph) 

 are present throughout the ooplasm except in the narrow periph- 

 eral zone and in the region occupied by the yolk nucleus which has 

 increased greatly in amount and is beginning to spread. Figure 

 15 shows this spreading of the yolk nucleus material clearly. 

 The irregular blocks and bands that may extend into any part of 

 the ooplasm are the 'Balken' of Holl ('90). Figures 16 and 18 

 show later stages of this process, only one of the numerous 'Bal- 

 ken' appearing in the sections. In both, the individual basophile 

 granules may be seen scattering in all directions ; eventually they 

 become evenly distributed thrgugh the ooplasm. Occasionally 

 the original center of the yolk nucleus may persist in later stages 

 (fig. 20), but usually the ooplasm now comes to appear homoge- 

 neous in paraffin sections. The study of material stained with 

 Sudan shows, however, that yolk spherules are still being laid 

 down at the periphery of oocytes of 0.3 to 0.4 mm. Figure 19 

 shows an oocyte of 0.3 mm. in which the spherules are confined 

 for the most part to a zone, sc, just inside the peripheral pro- 

 toplasm. This clearing of the central part of the oocyte, defining 

 the central and peripheral protoplasm with the yolk zone between 



