It may lead to a better understanding of the teaching contained in the following pages if it is here made clear just what is understood by the suffix “_itis_” in medical terminology. The old tendency was to regard all morbid conditions as expressions of inflammation in some of its protean manifestations. The attempt has been made in this work to distinguish as clearly as possible between _inflammation, as an expression of infection_, and the vascular, nutritional, and other changes which may be brought about by perverted nutrition without necessary participation of parasites. To describe “ostitis,” for example, as “inflammation of bone,” is to revert to an obsolete definition. Let us, then, always translate the termination “itis” as implying an _affection_, not necessarily an inflammation, of the structure named in the word to which it is affixed. With this conception of the word or the term there can be no contradiction in its use under various conditions, and one does not necessarily commit himself, by using it, to any definite view concerning the pathology of the affection which is thereby implied. With regard to one other feature there has been also a departure from previous nomenclature. The term “lymph glands” or “lymphatic glands” has always seemed objectionable, because, although they belong to the lymphatic system, they are in no sense glands, having no ducts, and no distinct secretion to be discharged through passageways. Whether in any sense they are to be regarded as furnishing an “internal secretion” is not the question here, their most obvious function being to act as filters. Throughout the work, then, the term “lymph gland” has been carefully excluded and the more accurate and far preferable term “lymph node” has been substituted. This seems to be a suitable place to explain the substitution and the reason therefor. PART I. SURGICAL PATHOLOGY. CHAPTER I. HYPEREMIA: ITS CONSEQUENCES AND TREATMENT.