ABSTRACT
The rod-shaped bacteria that aerobically form refractile endospores are assigned to the genus Bacillus. One spore appears in the spore-bearing cell, although some large rods observed in the intestines of tadpoles but never cultivated in vitro were described as forming two spores in the sporangium and assigned to the genus Bacillus.1 The endospores of the bacilli, like those of the Clostridia and a few other taxa,2 are more resistant than the vegetative cells to heat, drying, disinfectants, and other destructive agents, and thus may remain viable for centuries. The basis of the spore's resistance and longevity, its formation, morphology, composition, and stages of germination continue to be subjects of many investigations.3 , 4
