STAGE 6 ½. Age 3 ½ h.; length 1.4 - 1.5 mm.

Ext. Crit.:*Morula stage*. About 48 blastomeres. *In animal view about 6 micromeres along meridian*.

Int. Crit.: Blastomeres still arranges in single layer around cleavage cavity. *Synchronism of cleavages gradually lost; animal blastomeres in advance with respect to vegetative ones*. Plasmatic organization mainly as at fertilized egg stage, but distributed now over a large number of blastomeres. Distinction possible between animal, equatorial and vegetative blastomeres; transitions between cell types more gradual at dorsal than at lateral and ventral sides.