82 



T. H. MORGAN. 



April 12, 9 a. m. Further division has occurred. Black cells 

 are noticeably confined to the upper third of the egg, /. e., there 

 is"not the normal downgrowth (Fig. 20). 



24 / ^> as 



FIGS. 18-25. Segmentation stages of egg kept on ice. Rana palustris. 



April 12, 6 p. m. Condition same as last. Segmentation 

 cavity large. 



