I'LATK 3 



EXPLANATION OF FIGURES 



All the figures except 17 arc from photographs of sections of ovaries fixed in 

 sublimate-acetic-formol mixtures, cut 10m thick in paraffin and stained either with 

 neutral gentian or with neutral safranin-saurc violett. All were taken with a 

 Zeiss 4 nun. apochromat, ocular 4 and magnified 350 D. The germinal vesicle is 

 plasmolyzed more or less in every case. In each oocyte the 'typical' relations of 

 diagram 2 appear but the critical evidence for these conclusions was obtained from 

 fresh and creasote preparations and from free-hand sections. The measurements 

 are taken from the sections; the dimensions in life are estimated from 5 to 10 per 

 cent greater. 



9 Primordial follicle, 52 x44ju, cut in the long and polar axes, y.n., yolk nucleus, 

 surrounded by the spherules which ai)pear as vacuoles. 



10 Primordial follicle, 78 x 62yu, Horizontal section cut perpendicular to the 

 polar axis, near the animal pole. Note the germinal vesicle nearer one end of the 

 long axis. 



11 Primordial follicle, 83 x 60yu, cut in long and polar axes and showing the 

 stigma {si.) already formed in the long axis. 



12 Primordial follicle, 88 x 72ju, imbedded in the stroma so that the stigma has 

 not yet formed. Cut in long and polar axes. 



13 Primordial follicle, 95 x 83yu cut in long and polar axes showing the relations 

 of germinal vesicle (g.v.), yolk nucleus (y.n.) and spherule crescent {s.c.);f.e. 

 follicular epithelium. 



14 Oocyte at the beginning of the second growth period, 103 x lOOju, showing the 

 yolk nucleus material increasing in amount. 



15 Oocyte 277;u in long axis; second growth period. Cut in the polar axis, 

 transversely to the long axis, showing the stigma (st.) in cross section and the 

 increase of the sjjhendes (s.c.) The germinal vesicle is still peripheral and the 

 substance of the yolk nucleus (y.n.) has increased greatly in amount and is 

 spreading irregularly through the ooplasm. 



16 Oocyte, 203 x 166m; second growth period. Cut in the long and obliquelj' 

 to the polar axis. A later stage than fig. 15; from another ovary. The germinal 

 vesicle is no longer peripheral and the chromidial substance is diffusing through 

 the ooplasm. 



17 Oocyte, 198 x 162m, cut in the long and polar axes. Photographed from a 

 free hand section of an ovary fixed in formol-bichromate and stained with Sudan 

 III. The lipoid spherules, (s.c.) apjKMir black, the light(M- central region is the yolk 

 nucleus which is enlarging. The peripheral protoplasm (p.p.) is free from 

 spherules. 



18 Oocyte 280 x 255m; magnified 325 diameters and cut almost perjjendicular to 

 the polar axis. The section ))asses through the center of the germinal vesicle, 

 wliich is distinctly nearer to one end of the long axis. A cross section of one of 

 the 'Balken' appears at y.n. and shows clearly the (lilTnsioii of the chromidial 

 (?) granules. 



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