330 



GENERAL PRINCIPLES 



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

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



FIG. 190. The mature egg with 

 the polar body above. 



FIG. 191. Two-cell stage. 



FIG. 192. Four-cell stage. 



FIG. 193. Eight-cell stage. 



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



