Electron microscope studies of pleuropneumonia like organisms isolated from man and chickens.

The characteristic colony morphology is an important distinguishing feature which is used for recognizing members of the group of pleuropneumonia-like organisms. However, characteristic colony morphology may not be apparent when the organisms are freshly isolated from the body or when the growth is crowded on the surface of solid medium. In order to determine similarities or differences among the various strains of these organisms now being isolated from several sources, a study of their cellular morphology is desirable. This information may then aid in a more precise identification of these unusual organisms which is needed for their classification among microorganisms. The average diameter of the smallest phase of the saprophytic strains was shown by Laidlaw and Elford (1936) to be of the order of 125 to 175 m,u. Since this range is beyond the limits of resolution of the ordinary light microscope, the detailed morphology of these organisms needs to be obtained by means other than the light microscope. The electron microscope, especially with the aid of heavy metal shadowing, offers a means of obtamiing some of the necessary information. The results of studying with the electron microscope several strains of pleuropneumonia-like organisms from man and chickens are presented.