EN
Sexual immaturity in the Paramecium aurelia species complex is genetically controlled, its duratin being expressed by the number of cell divisions between successive conjugations or autogamies.During post-conjugational immaturity mating eractivity is regulated by a cytoplasmic protein - immaturin.The present study revealed that cytoplasm containing immaturin of Paramecium primaurellia injected into preautogampus cells of Paramecium tetraurelia does not inhibit the latter in entering autogamy.This results suggests that immaturin is inefective in the inhibition of autogamy.