Dissociation and Life Cycle of Bacillus mycoides

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Abstract
4 typical strains of B. mycoides were studied as to dissociation, pleomorphism, filterability and life cycle. Dissociation occurred in some liquid media tested, but not on agar. Rate of dissociation depends on several factors. 2 series of variants were found to occur in all the type strains. 7 non-adherent and 4 adherent colonial variants are described. All variants and the original type strains were similar in morphological and physiological characteristics. Pleomorphism is a marked feature in all aged cultures. The variant types of cells are not regarded as specialized reproductive cells, either asexual or sexual. No convincing evidence could be found to support the theory of reproduction by gonidia, sym-plasm, or conjugation. This conclusion is based principally on results of direct examination of growth in situ. All attempts to obtain growth from filtrates of liquid cultures resulted in failure. The evidence in favor of a cyclogenetic mode of development is mostly negative. Colonial polymorphism is regarded as due to ortho-genetic variation. The environmental conditions under which variation occurs, as well as the sequence of events and a possible mechanism, are discussed.