STAGE 8. Age 5 h.; length 1.4 - 1.5 mm.

Ext. Crit.:*Medium-cell blastula stage*. Surface not yet entirely smooth. Border of animal pigment cap more diffuse at dorsal than at lateral and ventral sides. Gradual transition between various regions still very gradual. *Pregastrulation movements noticeable for the first time*: slight epibolic extension of animal and equatorial areas and begining of ascendance of plasm along cleavage furrows near vegetative pole.

Int. Crit.: Outer cell layer single, inner cell material 1-4 cells thick; * first appearance of intercellular spaces between outer and inner cell material*. *First indication of distinction between animal, marginal and vegetative areas in inner cell material*. Continuation of pregastrulation movements.