62 



STAGING OF AMPHIBIAN EMBRYOS 



n^ 



FIRST CLEAVAGE - STAGE 3 

 (VEGETAL VIEW) 



I 



r^- 



SECOND CLEAVAGE - STAGE 4 

 (4 -CELLS) 



^^ 



THIRD CLEAVAGE - STAGE 5 

 (8+ CELLS) 





r^ J 



FOURTH CLEAVAGE 

 (8-16 CELLS) 



(RANA PIPIENS) 



