300 KING. [Vol. XVII. 



the development precludes its arising from distintegrating ma- 

 terial of the vesicle, and, therefore, I believe it to be but a por- 

 tion of the cytoplasm of the egg, forced up to or through the 

 surface by contractions in the egg-substance. After the for- 

 mation of the first polar spindle, I have found no marked 

 increase in the amount of perivitellin at the upper surface of 

 the Q.g^, as one would naturally expect to find if a portion of 

 the substance of the germinal vesicle had been extruded from 

 the Q.gg during the later maturation processes. 



Fig. 3 shows the germinal vesicle of the unripe ovarian 

 Q.gg. It is oval in outline, with a somewhat jagged border, and 

 its size is enormous when compared with that of the Qg2,, as it 

 measures 0.24 mm. by 0.34 mm. in an egg with a diameter of 

 I.I mm. At this stage the vesicle has left the center of the 

 ^gg, and lies a little eccentrically towards the black pole, with 

 its longitudinal axis oblique to an axis passing through the 

 light and dark poles of the egg (PI. XXVIII, Fig. i, GV). 

 Corresponding to Figs. 20, 21, of Schultze, the greater mass 

 of the nucleoli form a ring at the center of the vesicle ; the 

 few nucleoli that have not migrated to the center are at the 

 periphery, very close to the nuclear membrane. 



While most of the nucleoli are round or oval, occasion- 

 ally one is found which is triangular or decidedly oblong 

 (PI. XXVIII, Fig. 4). There is a great difference in the size of 

 these bodies : some are exceedingly small and can be seen only 

 under an immersion lens ; others are distinctly visible with the 

 lowest power of the microscope. The larger nucleoli gener- 

 ally contain one or two vacuoles, but the smaller ones always 

 appear perfectly homogeneous and take the same stain as the 

 chromatin. 



At this period all the chromatin threads are collected in the 

 center of the vesicle. They lie in the finely granular nuclear 

 sap, surrounded by the circle of nucleoli, and are composed of 

 very short, rod-shaped microsomes, which are arranged with their 

 longitudinal axes at right angles to the main axis of the chro- 

 mosome (PI. XXVIII, Fig. 5). The chromosomes are of vari- 

 ous lengths and usually much bent and twisted. A number of 

 them may be closely intertwined, and two may cross (Fig. 5, 



