DEFINITION.--Inflammation of some part or of the whole of the mucous membrane lining the bronchial tubes between the bifurcation of the trachea and the alveoli or air-cells of the lungs. The inflammation may vary in grade from simple hyperæmia, with increased irritability, to the most intense engorgement, exudation, and tumefaction of the membrane, and in activity from the most acute and rapidly-progressive to the most chronic and protracted in duration. SYNONYMS.--By the earlier writers the disease was called Peri-pneumonia notha, Angina bronchialis, and sometimes Erysipelas pulmonis. More recently it has been called Catarrhus suffocativus, Catarrhus pituitosus, Catarrhus bronchialis, Bronchial catarrh, and Bronchitis; _Fr._ Bronchite; _Ger._ Bronchialentzundung. Adopting the simple name of bronchitis, acute and chronic, in the further consideration of the subject I shall group the cases as they occur in general practice under the heads of Catarrhal, Mechanical, Capillary, and Pseudo-membranous Bronchitis. HISTORY.--During all the earlier periods of medical history bronchitis was generally confounded with inflammation of the membrane lining the larynx and trachea on the one side, and with pneumonia and pulmonary phthisis on the other. Among the earliest writers who gave more accurate descriptions of bronchitis as a distinct disease were Badham, J. P. Frank, and Broussais, in the latter part of the eighteenth century. Full and accurate descriptions of the disease, differentiating it from inflammation of other parts of the respiratory organs, were not given, however, until the discovery of auscultation by Laennec, and its practical application aided by percussion to the physical examination of the chest. This important addition to the previous means for studying the exact location and extent of all diseases within the chest, and the largely increased attention given about the same time to the study of morbid anatomy, soon led to as accurate an appreciation of the existence and extent of disease in any part of the organs of respiration and circulation as in any of the structures of the human body.