The high standard of this textbook of medical bacteriology and protozoology has been maintained in the present edition by a careful revision and an incorporation of the essential newer knowledge in the field. The wide experience of the authors allows them to furnish a critical opinion on numerous controversial subjects in bacteriology and public health. The enlargement of the section dealing with filtrable viruses is a welcome improvement, consistent with the more recently acquired information and the growing appreciation of their significance. While the volume is increased by fifty pages and several excellent illustrations, it is not too bulky. The arrangement of the chapters in a logical order of subjects is an improvement over the previous edition. The bacterial nomenclature is conservative and, although the book is remarkably free of typographic errors, one questions why the generic name "Hemophilus" is regularly spelled "Hemophylus."