A Peculiar Reproductive Process in Colon Bacillus Colonies. ∗ †

Abstract

In a previous publication attention was called to the fact that colonies resembling the L type colonies of Streptobacillus monilli-formis develop in various bacterial cultures. 1 Observations to date would seem to indicate that these L type of colonies originate from, or in close association with large swollen bacterial forms. If such observations have been interpreted correctly, then these large bacterial forms possess a definite biological significance. The occurrence of such large forms in bacterial cultures has been observed in the past. They have been regarded by the majority of bacteriologists as degenerative forms because they fail to multiply when transplanted.

In studying the L type of colonies, cultures of various bacterial strains were examined in the manner previously described in situ on the surface of the agar. If one examines such cultures from day to day one has an excellent opportunity of determining the fate of the large bodies. Our experience was similar to that of previous workers; 2 namely, that the large bodies disintegrate when transplanted without further development. During the course of this study, however, a single observation was made which seems sufficiently significant to warrant its being recorded.

Examination of a blood agar plate which had been inoculated with urinary sediment revealed large, intermediate, and tiny sized colonies. The larger colonies consisted of colon bacilli of the usual size and shape; whereas the tiny colonies were composed of long, wavy filaments showing all grades of transition into large fusiform or round bodies (Fig. 1). The large bodies were either uniformly stained or contained granules and vacuoles of different types. From Fig. 1 it is apparent that the large bacterial forms differ considerably from the normal appearance of colon bacilli.