||Several strains were grown on mixtures of peptone, proteose peptone, and thiotone dissolved in 3% NaCl, 0.25%K2HPO4 in pH 7.2. Culture flasks were incubated at 35°C and
160 rev/min in a gyratory shaker (New Brunswick
Scientific Co., New Brunswick, N.J.). Viable cell
counts were prepared from serial dilutions, and
turbidities of flasks were determined at appropriate
intervals from 0 through 24 hr. The generation time
for a given medium, determined from the maximum
tangent of a semi-log plot of turbidity versus time,
equaled the shortest time for doubling optical density.
Duplicate determinations were averaged.