Summary: In those members of the genera Bacterium and Bacillus studied, the constituent bacteria of Smooth cultures are typically unicellular, containing two chromatinic bodies. On division, a membranous septum is first formed, the bacillus subsequently dividing by constriction at this point.
The constituent bacteria of Rough cultures may comprise several cellular units, typically four, each containing a single chromatinic body and separated by membranous septa which, as growth proceeds, are transformed into true cell-wall septa, by the splitting of which the bacillus divides.
RobinowC.F.1944; Cytological observations on Bad. coli, Proteus vulgaris and various aerobic spore-forming bacteria with special reference to the nuclear structures. J. Hyg., Camb. 43:413