The Electron Micrography of Crystalline Plant Viruses

Abstract

Using an RCA Type EMB microscope, electron micrographs were made of ultra-centrifugally purified viruses of tomato bushy stunt, tobacco necrosis and southern bean mosaic diseases. The prepns. all behaved similarly but not identically, and showed ordered arrangements of particles. Specimens were made by allowing an aqueous suspension of the purified virus to evaporate on a collodion-covered screen, which was then shadowed at a 5 to 1 angle with 8 A of gold. The particles piled up into 2- and 3-dimensional patterns. It could be directly observed how the symmetry of a crystal was related to and detd. by the "shape" of its constituent elementary particles.