and counted directly. Strain Detrick-2exhibited significantly higher percentages of phase-bright spores than the Detrick-1 strain (Figure 7 , Mean +/2 standard error of the mean). Similar results were observed for the 1942 and Dugway strains (not shown). The 1013-1 strain exhibited an even higher degree of sporulation than the Detrick-1 strain under identical conditions ( Figure 7 ).