Recent investigations of fundamental importance dealing with pernicious anemia were doubtless the inspiration for this monograph. The authors have considered critically all of the important contributions concerning this disease, from the earliest description to the recent classic investigations of Peabody, Minot, Murphy, Cohn and Castle. All aspects of the disease are discussed comprehensively, including the historical development of knowledge, the physiology of blood formation and destruction, the pathology and etiology of the disease, and various clinical considerations dealing with the diagnosis, prognosis and treatment. Of unusual interest are the views of the authors concerning the etiology of the disease. They are in accord with the growing opinion in this country as they accept Cohnheim's original belief that the abnormal formation of blood is the primary factor in the disease and reject Hunter's hypothesis, which emphasizes hemolysis as the essential feature. They do not accept completely, however, the observations of Castle,