This book lives up to the expectation of the reader of the other Willis' classics : "Principles of Pathology," "Pathology of Tumours," and "Spread of Tumours in the Human Body." It encompasses an amazing sum of personal experience and of knowledge of very scattered subjects in the fields of medical and biologic literature This treatise makes for stimulating reading by offering a fresh point of view on old and seemingly settled problems, by brilliant treatment of classical subjectslike metaplasiaand by the insertion of these caustic, dogmatic and definitive remarks and unorthodox statements which are Willis' trademark. A good part of the teaching value of this admirable book may well derive from the stimulus of reader antagonism. One is constantly forced to reconsider the facts or one's interpretations in the quest for an argument in the lively dialogue conducted by the Master. It is obviously impossible for any one man to achieve proficiency in all the fields treated in the book and to append a perfect balanced and up-to-date bibliography to each chapter. Still, the numerous sins of commission or omission which may be picked up by specialists in narrow fields are mere trifles in view of the wealth of clear and condensed information and good basic bibliography.