The absence of a growth inhibitor during the log phase of growth of Dictyostelium discoideum

When amebae of the cellular slime mold Dictyostelium discoideum Ax-3 reach stationary phase in liquid nutrient medium, an extracellular factor appears which will inhibit cell multiplication when added to a logarithmically multiplying culture (Yarger et al., 1974). Recently, Hanish (1975) presented evidence that an inhibitor also accumulated during log phase and concluded that the cessation of cell multiplication and the final cell concentration were controlled by the accumulation of this inhibitor to an effective level. We have reexamined this extremely interesting observation, but have found no evidence to support Hanish's conclusions.