Twelve years has elapsed since the previous edition of this great book was published. A multitude of contributions on neoplastic diseases has appeared from all points of the scientific circle—physics, chemistry, physiology, pathology, clinical medicine and genetics—in the interim, necessitating extensive revision of many sections and the rewriting of some of the forty-nine chapters of the book. Dr. Ewing is most ably fitted to present a critical review of this expanding knowledge and to collect from the innumerable sources the essential facts and principles. He has omitted much historical material from this edition to make room for new contributions and yet has kept the volume within reasonable space. The general plan of the book remains the same. The author combats the theory that tumors fall into a limited number of grand classes in which the forms occurring in the several organs are so nearly related as to be virtually identical.