604 GEORGE T. HARGITT 



membrane about these vesicles, never a fusing of the chromo- 

 somes, and no loss of identity of the various chromosomes at 

 any time in the interim between the formation of the first and 

 second polar bodies. While they are still clumped together, and 

 before the second maturation spindle begins to form, there may 

 be a splitting of these chromosomes (figs. 15, 29) in preparation 

 for the next division. Occasionally this splitting for the second 

 maturation division was foreshadowed as early as the anaphase 

 of the first division (fig. 23). 



The second maturation spindle forms almost immediately 

 after the completion of the first mitosis, the spindle having the 

 same form as the first and, like it, lacking asters and centrosomes 

 (fig. 17). The second polar body is smaller than the first. So 

 far as observed the first polar body never divides though the 

 chromosomes may start to split longitudinally and then gradu- 

 ally degenerate. The polar bodies themselves degenerate and 

 grow smaller after they have been formed (fig. 18) and finally 

 disappear. The egg nucleus, reformed from the chromosomes 

 left in the egg after polar body formation, is much smaller than 

 the germinal vesicle and of a distinctly different appearance (fig. 

 18). There is no nucleolus, no coarsely grained, wide meshed 

 reticulum as found in the germinal vesicle (fig. 12), but a vesicu- 

 lar nucleus with the chromatin more or less localized along the 

 nuclear membrane. Possibly a definite reticulum may form 

 later. 



All of these changes occur while the egg is still within the 

 ovary. While the second polar body is being formed, or more 

 commonly after this has happened and the egg nucleus has 

 formed, the egg is liberated from the ovary by a rupture of its 

 outer wall. Eggs which have passed through the maturation 

 process have also been found in the cavity of the ovary. They 

 would probably escape from here a little later by a break in the 

 entire wall of the ovary; they are too large to pass into the 

 radial canals, and the latter method of escape is not one which 

 takes place in the hydrozoa, though it is the usual one in the 

 scyphozoa. Fertilization must take place after the eggs have 

 escaped from the ovary and are free in the water, for in none of 



