A Study of Microbic Variation in a Yellow Pigment-producing Coccus.

A consideration of present views relative to the nature of microbic variation shows several differences of opinion. This study was undertaken in order to obtain further evidence in regard to the nature of variation, which for the past decade has become of interest not only to students of medical bacteriology and public health, but also to workers in the fields of agricultural and industrial bacteriology. Microbic variation at the present time is a more or less universally accepted phenomenon. For an excellent and extensive review of the subject, including a complete survey of the earlier literature, the reader is referred to Hadley's work (1927). An extensive bibliography of the published works since Hadley's survey may be found in my original manuscript.2 This work was undertaken for the purpose of studying the cultural, morphological, biochemical, and to a limited degree, the immunological phases of variation in a recently isolated yellow pigment-producing coccus. The study includes a consideration of the growth cycle of this coccus which showed a motile phase. The work is limited to a discussion of the methods of obtaining the variants, the character of the changes observed, the possibility of filterable forms and a growth cycle showing changes in the morphology of the organism.