Electron microscope studies of bacterial viruses

viruses (bacteriophages) in the last few years have led to a revival of interest in this group of viruses, particularly as a material on which one can study under very favorable conditions properties which may be common to all viruses. Ease and accuracy of titration and the possibility of working under biochemically con-trolled conditions make bacterial viruses an ideal object for such investigations. The electron microscope, recently introduced as a tool for biological research, has been applied to the study of animal and plant viruses, and also of bacterial viruses (Ruska, 1940; Pfankuch and Kausche, 1940; Ruska, 1941; Luria and Anderson, 1942). Ruska (1941) published micrographs of suspensions of bac-terial viruses, in which “sperm-shaped ” particles can be seen. Ruska suggested that these particles should be interpreted either as the virus itself or as bacterial constituents