During the five years that have elapsed since the appearance of the first edition of this book, the advancements in pathology, particularly along certain lines, have made it necessary to practically rewrite much of the work, and this is what the author has done. The greatest changes are in the chapters on the pathology of the blood, on inflammation and on the pathology of infection and immunity. The need of a more uniform classification of the varieties of lecucocytes is apparent, as the terms applied to the same kind of cell by different writers are confusing to one not perfectly familiar with the subject. The greatest advancements in the future are to be hoped for along clinical lines, hence "The Pathology of the Blood Plasma" forms a very interesting chapter. The modern conception of infection and immunity as set forth by Ehrlich in his side chain theory is well presented.