The ninth edition of the Park, Williams and Krumwiede "Pathogenic Microorganisms" scarcely needs an introduction to students and workers in bacteriology. For many years the previous editions of this text have been accepted as a standard guide, and the ninth edition ranks with the others. The arrangement of the chapters into three parts is continued in the new edition but with some slight changes. The first part deals with the methods for studying bacteria. Procedures for sterilization, for the preparation of many mediums, for culturing bacteria and for carrying out immune reactions are described in detail and with ample discussions. This part also includes the technic for the complement-fixation tests and the Kahn and the Meinicke tests.
In the second part consideration is given to the individual pathogenic microorganisms, the bacteria in particular, the protozoan parasites and the vegetable forms higher in organization than the bacteria. The chapters on the