Phytoplankton--the passively floating or weakly swimming plant life found in bodies of water--is generally inconspicuous. It is of basic importance in lakes and seas, however, as the primary producer of the organic material on which other forms of aquatic life depend; and it is probable that its total photosynthetic output exceeds that of land vegetation. This book reviews the information gained from culture studies in the laboratory on the growth kinetics and metabolism of algae and considers to what extent this information is applicable to phytoplankton populations in nature. Dr. Fogg has laid a solid foundation for such future investigations in this precise, clear, and factual review, which admirably integrates laboratory and field data. His book will be valuable not only to limnologists and marine biologists but to many botanists and zoologists who do not consider themselves primarily limnologists. Judiciously chosen illustrations, including three full-color plates, add to the usefulness of the text.