Some Properties of a Genetic Cytoplasmic Factor in Paramecium

Abstract

A number of stock G animals obtained from a single killer (which had gone through 16 rapid fissions at a rate of 3.3 per day) were removed and allowed to go through additional fissions at a rate of 3 per day. After 8 and 15 rapid fissions, 14 out of 128 and 13 out of 127 of the original animals, respectively, gave rise to exclusively permanent sensitive progeny. That there was no increase in percentage is in agreement with the assumption that one particle is sufficient for reversion. Attention is called to the fact that self-reproducing cytoplasmic components may not increase at a rate strictly correlated with the growth rate of the cell.