330 



GENERAL PRINXIPLES 



(Figures 190 to 210 represent the early steps in the development of Amphioxous 

 Rranchiostomu). According to the wax models of Ziegler, Freiburg, i. B. 



lu".. iQO. — The mature egg with 

 the polar body above. 



Fig. 191. — Two-cell stage. 



Fig. 192. — P'our-cell stage. 



F'iG. 193. — Eight-cell stage. 



Fig. 194. — Sixteen-cell stage. Fig. 195. — Thirty-two cell stage, in section. 



