Immaturity substances: Material basis for immaturity in <i>Paramecium</i>

Abstract

ABSTRACT Cells of Paramecium caudatum in the immaturity period of the life cycle contain substances which repress the expression of mating ability when introduced into mature cells. When 5 × 103μm3 of immature cytoplasm were injected into mature cells, loss of mating ability occurred and it continued for more than 15 fissions after the injection. The effective substances are contained in the soluble fraction of immature cells and have the properties of heat-labile macromolecules.