=False Membranes= may be found in the larynx and trachea in fatal cases of croup or diphtheria. In croup, the membrane adheres but slightly to the mucous structure beneath, which will be found red and congested, but may form a complete tubular lining to both larynx and trachea, extending also into the bronchial tubes.[7] It is usually tougher in the larynx and upper portion of the trachea, becoming softer and more gelatinous in the lower portion of the trachea and bronchial tubes. Much difference of opinion has been entertained as to the nature of this substance. It may, however, be considered as a morbid secretion from the inflamed mucous surfaces, in a semi-fluid form, which, in consequence of the presence of albuminous matter, coagulates upon exposure to air. The false membrane of croup may generally be distinguished from that of diphtheria by the fact, _First_, That the latter is usually confined to the fauces, sometimes extending to the larynx, rarely to the trachea. _Second_, That diphtheritic membrane occurs more in patches, is tougher, is more directly incorporated with the mucous surface beneath, and is removed with more difficulty. _Third_, A microscopic examination shows the membrane to be composed mainly of fibrine in a fibrillated condition, with granular corpuscles and pus cells. Section III. OF THE PHARYNX AND ŒSOPHAGUS. [=Notice= in examination: displacements; their cause, as by tumors, etc.; dilatation; contraction or stricture, seat of; calibre at stricture; above, below; condition of mucous membrane; ulcers, etc. Contents of œsophagus; food, foreign bodies, wounds.] These parts are liable to _inflammation_, _ulceration_, _stricture_, _dilatation_ and _new growths_. =Inflammation= of these passages, rarely occurs, except as the result of mechanical injury, as from the lodgment of a foreign body, or from swallowing some caustic or highly irritating substance. Catarrhal or croupous inflammation of the mouth and tonsils, may, however, involve a portion of the walls of the pharynx. =Ulceration= may result from the same causes, and hence may be confined to a small portion or may involve the greater part of the tube. =Stricture= of the œsophagus may be either _spasmodic_ or _organic_. The former usually occurs in hysterical women, and may result from the irritation following the removal of some foreign body lodged in the canal. Never proving fatal of itself, we seldom have the opportunity of examining a case of this kind. _Organic stricture_ is found usually at the commencement of the canal, sometimes at its lower end. It may result from contractions attending the healing of an ulcer, but is more frequently induced by a cancerous affection of the walls, or by the projection of some morbid growth into its interior, as from aneurism of the aorta, or tumors, abscesses, &c., in the lungs or left lobe of the liver.