Figure 7. Development of an RNA-rich mass on the ventral side in a 

 neurula originating from a centrifuged blastula (Pasteels and Brachet, un- 

 published). 



/ 



Z' 



/ 





■■ ■•'? 







Figure 8. Differentiation of an RNA-rich secondary embryo from a centri- 

 fuged blastula (Pasteels and Brachet, unpublished). 



