STAGE 9. Age 7 h.; length 1.4 - 1.5 mm.

Ext. Crit.:*Fine-cell blastula stage*. Animal cells are smaller at dorsal than ventral side. *Border between marginal zone and vegetative field distinct*, particularly dorsally, owing to difference in cell size.

Int. Crit.: Sharp delimitation of outer cell layer in animal and equatorial regions; outer later segregated into presumptive ectodermal and entodermal areas with rather abrupt transition at level below equator. Inner cell material more sharply segregated into presumptive ectodermal (animal), mesodermal (equatorial) and entodermal (vegetative) areas. Blastocoel has attained its full size; inner surface smooth.