This is part of a comprehensive up-to-date reference work on mineral metabolism and is the second of two volumes dealing with principles, processes, and systems. In Volume I, Part A, physical and chemical principles and the physiological processes absorption and excretion were covered. In this volume biological principles are emphasized and the major tissues discussed. Irving I. Geschwind has a chapter on hormonal control of calcium, phosphorus, iodine, iron, sulfur, and magnesium metabolism. The hormonal control of sodium, potassium, chloride, and water metabolism is discussed by M. B. Lipsett, I. L. Schwartz, and N. A. Thorn. All the elements considered here from the viewpoint of their hormonal control will be exhaustively treated individually in subsequent volumes. J. F. Manery reviews minerals in nonosseous connective tissues including the blood, lens, and cornea. The metabolism and homeostatic function of bone is covered by G. C. H. Bauer, A. Carlsson, and B. Linquist.