The first edition seems to have fulfilled a need for a general text-book on the subject of bacteriology. The original method of presentation is preserved. The text-book idea is adhered to, so that the individual instructor may have full liberty to expand on topics in which he is especially interested. A number of illustrations have been added, the text has been improved in many instances by the addition of further explanatory matter and the most recent general advances in the Science. Examples are the System of Classification of the Society of American Bacteriologists, which is used throughout the text, their Key to the Genera of Bacteria, a discussion of the H-ion concentration method of standardization, the selective action of anilin dyes, the mechanism of entrance of pathogenic organisms into the body, a more detailed explanation of the origin of antibodies, the nature of antigens and a table of antigens and antibodies.

Professor Vera McCoy Masters has assisted in the revision by aiding in the preparation of manuscript and the reading of proof and in the making of the index, for which services the author’s thanks are hereby expressed.