Specificity of the immaturity substances in Paramecium

Cytoplasm of Paramecium caudatum syngen 3 in the period of sexual immaturity was effective in inducing immaturity when injected into mating-reactive cells of other syngens of P. caudatum. When immature cytoplasm of P. caudatum was injected into mature cells of P. multimicronucleatum, immaturity was also induced in the latter cells. When cytoplasm of P. bursaria in the immaturity period was injected into mature cells of the same species, the latter became immature. But immature cytoplasm of P. caudatum was ineffective when injected into mature cells of P. bursaria. When immature cytoplasm of P. busaria was injected into mature cells of P. caudatum, no difference from the control was observed. These results suggest that a difference in specificity of the immaturity substances exists bewteen paramecia of the 'aurelia' group and those of the 'bursaria' group.