CLEAVAGE 



251 



FIG. 120. Continuation of Fig. 119. H. Dexiotropic division of la l -\d> and 

 of 2a-2d. From animal pole. I. Thirty-two-cells, from animal pole. J. 

 Thirty-two-cells from vegetal pole. K. Thirty-two-cells from right side. L. 

 Late cleavage showing the history of cells 4a-4d and 4A -4D. M . Optical section 

 of a much later stage, viewed from near the vegetqj pole. The mesoderm bands 

 are stippled. 



