122 The Phenomena of Morphogenesis 



form and fixed, presumably because of the higher level of organization 

 and differentiation among them. It must have its origin verv early in 

 embryonic development. Vochting's conclusion, however, that every 



Fig. 6-3. Transverse polarity in Dioscorea. 

 Half slice of a tuber with regenerating 

 shoots next the core and roots on the 

 periphery. ( From Goebel. ) 



cell is polarized has been challenged by those who point out that many 

 cells theoretically may become completely embryonic again and ulti- 

 mately produce an entire plant and thus can have no fixed polar charac- 



