26 MORPHOGENESIS IN CILIATES 



May I quote here an opinion of Sewall Wright (1941), 

 discussing some problems of differentiation: ^The stability 

 of the changed state certainly becomes easier to understand 

 if it is postulated that there are self-duplicating materials 

 within the cell which can become modified chemically and 

 multiply as of the new sort." 



The self-duplicating kinetosomes, able to give rise to 

 self-duplicating trichitosomes, would illustrate this con- 

 clusion very nicely. 



