=Causes of temporary roaring.= Whatever impedes the current of air causes roaring. Hence inflammatory diseases of the nose, throat, windpipe or bronchial tubes; abscess of one or the other of these parts; inflammation of a jugular vein and pressure on the trachea or vagus nerve by the resulting swelling; choking; the swelling in the neck consequent on the cutting open of the gullet for the relief of choking; thickening of the nostrils from dropsy, loss of a jugular vein, purpura hemorrhagica etc.; and swellings pressing on the vagus nerve, and which may be situated at the base of the brain, in the neck or in the anterior part of the chest. Also temporary infiltration of the laryngeal mucosa. =Causes of inveterate roaring.= The one great cause of roaring and that which sustains the disease in nineteen cases out of every twenty is paralysis of the left _recurrent nerve_ of the larynx and wasting of several of the arytenoid muscles on that side. It may be well, however, first to notice the less frequent causes and wind up with this more common one. 1st, Fracture with distortion of the nasal bones and narrowing of the nasal passages (Gamgee). 2nd, Polypi and other tumors of the nose, pharynx, larynx, windpipe or bronchi. 3rd, Chronic thickening of the nasal mucous membrane, the result of inflammation. 4th, The presence of foreign bodies in the nose, as for example balls coughed up from the pharynx. 5th, Hering records a case resulting from the closure of the posterior opening of one nasal chamber by a membrane. 6th, Cancerous or melanotic deposits in the lymphatic glands above and to each side of the pharynx and larynx. 7th, Distension of the guttural pouches by inspissated pus. 8th, Chronic thickening of the mucous membrane of the larynx consequent on inflammation. 9th, The formation of a projecting fold of the mucous membrane or of a new production (false membrane) in the windpipe as the result of inflammation. Such false membranes have been known to become detached at their median part and remain attached at their two extremities thus constituting a band stretching from one side of the windpipe to the other. 10th, Ulceration of the membrane of the larynx particularly on the projecting folds circumscribing the glottis, 11th, Ossification of the laryngeal cartilages and loss of their elasticity. 12th, Distortion of the cartilages of the larynx, most commonly from unduly tight reining and pulling the nose in toward the chest. In such cases the cartilages of the larynx and those of the windpipe adjoining being compressed slide within each other, and the enclosed edge projecting within the air tube materially diminishes its calibre. 13th, Fracture of one or more rings of the trachea. This usually results from blows, as in running the neck against the back of a cart or wagon. The cartilaginous rings are usually broken at their median part in front and being retained together by the