抄録
Electron microscopic observations of a BCG strain on ultra-thin sections showed that the cell was composed of a cell wall, cytoplasm containing large electron-optically dense granules and a chromatin thread-like structure in a clear area. The chromatin thread-like structure had fine granules 15-20mμ in diameter attached to it, and extended through the central part of the cell along its longitudinal axis. It gave off fine fibers into the cytoplasm and was supposed to be connected with A-granules at the end portions of the cell. A-granules were isolated by ultracentrifugation from the cells of BCG and Mycobacterium phlei after the cells were disintegrated by repetition of freezing and thawing. Measurement of ultraviolet absorption of the fractions obtained by ultracentrifugation disclosed that the nuclear substances were dissolved and transferred into fraction III after the cells were disintegrated and that fraction II containing A-granules absorbed little or no ultraviolet light. Separated A-granules were identified with those in the cells on the basis that electron bombardment vacuolized all these granules.
