Six new chapters have been added to the book, viz. Epidemic jaundice, rat bite fever, tularaemia, tables of helminthic and arthropodan diseases, trench fever, in Part I, and, in Part II, a chapter on the diagnostics of tropical joint, muscle and bone lesions. Extensive additions have been made to Chapter XLIII, “Diagnostic problems and procedures, together with cosmopolitan diseases in the tropics”; and in the chapter on blood examinations will be found a presentation of our latest views as to acidosis as well as a table giving the significance of the findings in blood chemistry. Many new illustrations have been added and some of the older ones replaced by others of greater teaching value. Every effort has been made to retain the feature of a pocket manual but it has been necessary to increase the number of pages from 524 to 610. The illustrations in the third edition numbered 119; in this edition, 159. In particular I have to express my indebtedness to Commanders C. S. Butler and H. W. Smith of the Naval Medical Corps for advice and assistance in the preparation of this edition. Dr. G. W. McCoy, Director of the Hygienic Laboratory, has given me valued suggestions as to changes in some of the old chapters and in the preparation of the new chapter on Tularaemia. Lieutenant Commander Bunker, the head of the Chemical Laboratory of the Naval Medical School, has made the revisions of the subjects dealing with physiological chemistry. Others, who have given me advice and suggestions, have been Lieutenant Commander Reed and Lieutenants Harper and Chambers of the Naval Medical School. To Lieutenant Peterson I am indebted for assistance in the proofreading and preparation of the index as well as in going over the recent literature of tropical diseases. PREFACE TO FIRST EDITION There is no more striking evidence of advance in general medicine than the present attitude of the physician or rather internist in the diagnosis of the cases met with in a modern hospital ward. Instead of first considering the evidence obtainable at the bedside and then noting the laboratory findings as something apart and entirely subordinate, we now find the two aids to diagnosis so correlated that it is as difficult to note one kind of information as bedside and other as laboratory as it formerly was to separate signs from symptoms in the study of a case. In tropical medicine, however, we have for many years made our diagnosis in the laboratory, the bedside playing a subsidiary part—the laboratory diagnosis is controlled by the bedside findings.