282 SEX IN iMICROORGz\NISAIS 



mic interactions, in which the cytoplasm determines the nature of 

 the macronucleus and is in turn redetermined by that macronucleus. 

 This pattern of nucleocytoplasmic cooperation emphasizes the con- 

 clusion that the cytoplasm is not a passive, but an active partner in 

 cellular heredity. 



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