The tenth edition of this well known book differs from the previous edition only through the attempt of the author to keep it abreast of the times. He has made extensive revisions of the sections on undulant fever, the paratyphoid group, the filtrable virus diseases, pathogenic yeasts, anaerobes, and the section on variation. The subject of bacteriophage has been handled with greater detail than heretofore, and minor changes have been made in many other chapters. The author has tentatively employed some generic names that have come into general use, such as salmonella, mycobacterium and brucella, and he has reluctantly introduced even the term eberthella. He recognizes that nomenclature in bacteriology is still a vexed question and will remain so until a general system can be worked out by international agreement. The author does not, of course, attempt the impossible task of extensively treating in one fairsized volume all of bacteriology.