August Krogh, Nobel Laureate in Medicine and Biology, was one of the twentieth-century's great physiologists. This book, based on a series of lectures delivered at Swarthmore College in 1939, has since come to be recognized as a classic of exposition.

This book is a concise study of the structure and function of vertebrate respiratory systems. It describes not only the individual organ systems, but also the relationship of these systems to each other and to the animal's environment. For example, the author emphasizes that a proper understanding of respiration involves a consideration of the external environment as a source of oxygen as well as the biochemistry of the cell; and, from the evolutionary point of view, that physiological changes in the respiratory and circulatory systems are dominated by the origin of the land habit. The author's approach to the subject exemplifies that trend to the amalgamation of Zoology and Physiology, which has become increasingly marked at universities and schools in recent years. This synthesis requires, broadly, a knowledge of classical comparative anatomy, ecology, evolution, physiology and biochemistry; an enormous task, but nevertheless one in which the zoologist holds a central position. This book indicates the nature of such an eclectic approach, with the animal, in its environment and its evolution, as its focal point. Covering a rapidly changing field of research the author refers to many recent views and indicates where these differ from those commonly accepted.

How do vertebrates get the oxygen they need, or even manage without it for shorter or longer periods of time? How do they sense oxygen, how do they take it up from water or air, and how do they transport it to their tissues? Respiratory system adaptations allow numerous vertebrates to thrive in extreme environments where oxygen availability is limited or where there is no oxygen at all. Written for students and researchers in comparative physiology, this authoritative summary of vertebrate respiratory physiology begins by exploring the fundamentals of oxygen sensing, uptake and transport in a textbook style. Subsequently, the reader is shown important examples of extreme respiratory performance, like diving and high altitude survival in mammals and birds, air breathing in fish, and those few vertebrates that can survive without any oxygen at all for several months, showing how evolution has solved the problem of life without oxygen.