This year's volume of this series contains chapters on the physical properties of protoplasm, growth, the physiology of the connective tissues, physiological effects of heat and cold, energy metabolism of biosynthesis at the cellular level, water metabolism, the respiratory system, comparative physiology of invertebrate muscle, the digestive system, blood clotting, blood gas transport, peripheral circulation, the heart, lymphatic system, the kidneys, excitation and transmission in the nervous system, the somatic and the visceral functions of the nervous system, hearing, the thyroid, the skin, and the pituitary-adrenal system. This last-mentioned subject deserves the attention of practicing physicians who seek fundamental information about corticotropin (ACTH) and related substances that have recently come into use. In general, the volume abounds in material that is either of immediate interest or suggests the probable direction of further developments. The book as a whole is not only an index of the overwhelming diligence of present-day research