H. H. NEWMAN. 



20 



21 



FIGS. 1321. Camera lucida outlines of optical sections of normal larvae 

 derived from fertilized eggs and drawn off from the surface of the dish. 

 These normal larvae never show " apical plate " nor " anterior vesicles." 

 FIGS. 1315 drawn about 24 hours after fertilization. FIGS. 16 18 drawn at 

 about 48 hours. FIG. 19 drawn at 30 hours. FIGS. 20 and 21 drawn at 72 hours. 



