Recent Progress in Studies of Mouse Type-C Viruses.- Viral Envelopes and their Relationship to Cellular Membranes.- Head Size Determination and the Morphogenesis of Satellite Phage P4.- The Biochemistry of Icosahedral Cytoplasmic Deoxyviruses.- Structure and Synthesis of Bacteriophage PM2 with Particular Emphasis on the Viral Lipid Bilayer.