38 



indicate that suoh a change takes place. In eggs taken soon 

 after spwaning the sperm-vesicle has increased considerably 

 in size and the wall has taken on a vesicular appearance. 

 This is shown in Figs. 110 eoid 111 which show the sperm-ve si- 

 de in two different aspects. The cavity of the vesicle 

 gradually disappears leaving only a notch on one side (Pigs. 

 108, 109, 110 and 112). Figure 112 was about an hour old. 

 In eggs two hours old the vesicle has taken on the appearance 

 of an ordinary nucleus containing granules of chromatin (Fig. 

 116). At this time it has gone about one fourth of the dis- 

 tance from the circumference to the center of the egg (Fig. 117) 



We will now turn our attention to the egg-nucleus. When 

 the eggs are set free in the lumen of the ovary Just before 

 spawning begins, the spindle for the first maturation division 

 is already formed and its long axis is parallel with the sur- 

 face of the egg (Fig. 113). As the egg passes through the 

 oviduct the spindle turns to a position perpendicular to the 

 surface of the egg and the first polar body is cut off. This 

 is shown in Fig. 114 which is from em egg that has Just pass- 

 ed out of the oviduct. Efforts were made to count the chrom- 

 osomes just after this division. Twenty-five to twenty-eight 

 were counted. Thus the double number would be fifty to fifty- 

 six. They are however so small and placed so closely together 

 that it is difficult to distinguish them accurately. 



Between one and one and a half hours after spawning the 

 second maturation division takes place. The second polar 

 body is apparently not cut off, but remains in the egg where 

 it degenerates and is absorbed by the cytoplasm. 



