94 BLASTULATION 



Animal hemispheres^ Segmentotion cavity (blastocoel) 



~ Vegetal hemisphere 



Hemisected blastula 



Segmentotion covity (blastocoel) 



Lote biostula 



Hemisected late blaslulo 



Blastulation in the frog. (Redrawn and modified after Huettner.) 



Vegetal hemisphere 



Frog blastula: sagittal section. 



