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June 12, 1943


JAMA. 1943;122(7):443-444. doi:10.1001/jama.1943.02840240033013

The tubercle bacillus survives a temperature as low as that of liquid helium as well as freezing up to two hundred times with liquid nitrogen.1 In this remarkable resistance to cold the bacillus differs from mammalian cells and tissues, the activities of which are retarded in temperatures near the freezing point but which in general do not survive actual freezing. The prolonged survival of the bacillus when frozen may be explained by dormancy on the part of its enzymes under low temperature. The bacillus can survive desiccation also.2 Hermetically sealed in glass capsules containing less than one billionth of an atmosphere, the bacillus survived more than one year at body temperature. In this experiment the bacillus was very dry, which may have contributed to its dormancy. Incubated in a partial vacuum, saturated with water vapor but deprived of oxygen, the bacillus lost all power of growth, even when