148 MUNSON. ■ [Vol. XV. 



contrasted with the previous stage is marked by the consider- 

 able loss, by the cytoplasm, of that affinity for chromatin stains, 

 and by the greater size and clearness of the centrosphere. The 

 yolk granules are more abundant and many of them seem to 

 have increased perceptibly in size. 



Stage III. — In this stage the germinal vesicle is relatively 

 more excentric in position, and subject to great variations in 

 form and size. Compared with the amount of cytoplasm and 

 yolk it is perceptibly smaller. The nucleolus is often very 

 large relatively, and shows many irregularities in form and 

 structure. Numerous " Nebennucleoli " exist. The chorion 

 has increased greatly in thickness by the addition of new 

 layers. The cytoplasm is conspicuously marked by a polar 

 differentiation, one pole being rich in yolk granules and the 

 opposite pole comparatively free from these granules. 



At the end of this period the germinal vesicle lies close to 

 the periphery, partly surrounded by a spongy, hyaline proto- 

 plasm that does not stain readily. The ^g% having attained 

 about half of its normal size, but as yet showing no true yolk 

 spheres, is at the end of this period discharged into the ovarian 

 tube. The manner in which this appears to be accomplished 

 has been described above. The egg has now entered on its 

 fourth and last stage. 



Stage IV. — This stage is marked by a modification of the 

 cytoplasm that renders sectioning in parafifine extremely diffi- 

 cult. This appears to be due to marked changes in the yolk 

 granules. These assume regular spherical forms, and increase 

 very rapidly in size. Owing to the rapid increase of the yolk 

 spheres the egg increases proportionately in size, and this 

 increase in size appears to be a very rapid one. In the first 

 periods after its discharge from the follicle the egg can still be 

 sectioned in paraffine, but the yolk bodies can be seen to have 

 become vesicular and regular in outline, though still compara- 

 tively small. The yolk bodies, even now, adhere less firmly to 

 the slide, so that passing the slide through different grades of 

 alcohol or even dissolving the paraffine is liable to wash many 

 of them away. This was not the case in the previous stages. 

 All transition stages from these first definite yolk spheres to 



