AbstractInfection of secondary Chinese hamster cells with SV40 virus induces a population of cells into consecutive S periods. These changes in DNA content were examined at various times post infection by means of flow microfluorometry (FMF) which enabled a kinetic analysis to be made. At 12 h post infection, a population of 6C cells was observed which was induced from late S or G2 cells. By 24 h post infection, cells at 8C, 10C, 12C, 16C, and intermediate DNA contents were detected. The induction of this population of cells occurred within the first 24 h post infection. At later time intervals, there was a decrease in total number of cells with DNA contents of 8C or 16C.