

Fig. 58a. — ^Segmentation of the egg of African Qawed Toad, Xenopus laevis. I. 

 The unfertilized egg with pigment and the nucleus in its upper hemisphere. 

 II. The 8-cell stage, seen from below. III. The early blastula or ' ball of cells ' 

 stage. (.After E. J. Bles.) 



