108 MR. XOEL TATLER ON A UNIQUE CASE OP 



It is of extreme intei-est, therefore, to find in Blastoderm E a 

 case of unequal duplicity in which there can be no room for doubt 

 that the two embryonal formations were from the first unlike, 

 the asymmetry therefore being intimately bound up with the 

 actual origin of the two centres of embryonal formation from a 

 single centre, and not resulting from secondary modification 

 during the course of development. 



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