Engström-Finean Biological Ultrastructure, Second Edition, looks upon biological phenomena essentially as patterns of physical and chemical events organized in space and time. It attempts to describe the spatial aspects of this organization, emphasizing in particular the fundamental roles of individual types of molecules. It also introduces a minimum background of fundamental structural information and of techniques so as to aid in the appreciation of the significance of experimental data. The plan of the book in the present edition remains unchanged but the tremendous advances of recent years have necessitated changes in emphasis in the treatment of methods and fundamentals of structure and a complete reappraisal of biological ultrastructure. Key topics discussed include methods in ultrastructural research, the principles of molecular structure; the role of proteins, nucleic acids, lipids, carbohydrates, mineral salts; and the role of ultrastructure in biology and medicine.