Giant colony patterns exhibited by a pseudomonad.

A bacterial colony on the surface of a solid medium is regarded as a grouping of cells arranged as a result of physical restrictions imposed by the surface of the medium. It is limited in size by the physical nature of, and changes occurring at, this surface (Knaysi, 1951). In a biological sense the bacterial colony is a macromorphological collection of cells rarely found in nature (Pringsheim, 1955). When a Pseudomonas species displayed several unusual colony patterns it appeared that the recording of this phenomenon, together with attempts to explain the factors responsible for the colony patterns, might contribute to the knowledge of bacterial macromorphology.