CYTOLOGICAL OBSERVATIONS ON THE CHROMATIN BODIES OF TWO BACILLUS SPECIES

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Abstract
The nature of the chromatin bodies in Bacillus anthracis and B. megaterium has been studied intracellularly as well as after isolation from the bacilli. Preparations were examined by phase-contrast microscopy in the living state and by acid-Giemsa and Feulgen staining. In cells from young cultures chromatin bodies occupy a continuous, long central area in the bacteria. As the cells mature the bodies lose their continuity and divide into two halves. In cells grown for 24 hr. or longer the chromatin bodies become more complex and appear as multiple, spherical interconnected constellations. Nuclear staining reveals that only the peripheral area (whether in cells from young or older cultures) takes up the stain leaving a clear central core. Discrete chromatin bodies are liberated from cells grown for longer periods after disintegration of the bacterial cell wall. These discrete bodies have been isolated from whole bacteria by treating washed buffered saline suspensions of old cells with high concentrations of lysozyme followed by digestion with purified pancreatic lipase. The isolated chromatin bodies retain the same structure and appearance as inside the cells and show the same staining characteristics. Observations suggest that the chromatin bodies are discrete and circumscribed in nondividing resting-phase bacteria.