This new edition of the author's Handbook of Protozoology (1931) has been completely rewritten, reset and greatly enlarged. Whereas the first edition had 175 illustrations showing 1,463 figures, this edition has 291 illustrations with 2,711 figures. As now constituted it offers the content of textbook, laboratory manual, reference work and an atlas of the free-living and parasitic Protozoa. The first six chapters treat of the ecology, morphology, physiology, reproduction and variation and heredity of the Protozoa, and chapters 7 to 43 give a systematic analysis of the families, many of the genera, and the more significant and representative species of this marvelously diverse group of so-called simple organisms. It is a valuable work of reference for every medical library.