This book is aimed at undergraduate students of vertebrate physiology and biology but, as is the case with previous books written by Professor Knut Schmidt-Nielsen, professional biologists of all age groups are likely to change their outlook and views in the course of reading it, sometimes substantially. Why is this? First, because style and contents make up such an integrated whole that I for one felt compelled to read the book from beginning to end in one go. The major reason, however, is that, although firmly rooted in classical physiology and morphology, Schmidt-Nielsen is never conventional and is able to see new and surprising solutions and relationships. It is the mixture of classical scholarship and common sense with the innovating spirit of an artist which has led him and his collaborators to an understanding of how animals survive in deserts, the existence and function of the salt glands in birds and reptiles and, as it now seems, to the solution of a classical problem, the function of the bird's lung.

For the zoologist as well as for the general reader, the book has another charm. It is written by a true cosmopolitan who has brought together personal experience and examples from five continents, and, in spite of all this, one can almost hear through the lines the characteristic Norwegian accent.