280 GEO. W. TANNREUTHER. 



Explanation of Plate XI. 



Fig. 33. Longitudinal section of aboral end of hydra, showing eggs in different 

 stages of development ; e.c, ectoderm surrounding egg ; p.b, polar bodies; prn, pro- 

 nucleus ; e.m, egg membrane. 



Figs. 34-36. Surface views of living eggs, showing first cleavage ; side view ; p.c, 

 protoplasmic connections ; p.b, polar bodies. 



Figs. 37 and 38. Second cleavage, side view. 



Fig. 39. Polar view of second cleavage. 



Figs. 40-42. Third cleavage of living egg ; side view ; p.b, polar bodies. 



