Determination of Macronuclear Fragmentation,Stabilization of Cell Union,and Cessation of Feeding Activity in Triplet Conjugants of Paramecium1

Triplet conjugants of Paramecium multimicronucleatum, in each of which the third cell unites by its anterior and to a posterior part of one of the conjugating pair, are induced by conjugation inducing chemicals, KCl and acriflavine in a Ca¹¹-poor condition. If the triplets are prematurely transferred to medium free of such chemicals, the third cells usually separate and no macronuclear fragmentation occurs in them. But in third cells of long lasting triplets, macromuclear fragmentation regularly begings at ～12 In after chemical treatment Staluhzaton of cell union and determmation of macronuclear fragmentation occured between ～100 and ～130 min after initiation of chemical treatment. Electron-microscopic observation of the stabilized third cell revealed that the two cell membranes at the uniting region were partially fused to form cytoplasmic bridges. Chemically treated cells began to cases feeding before the cell union and fully ceased such activity at ～130 min after the treatment.