The disease or accident which renders the operation necessary varies greatly, and upon this variation depends not only the surgeon's decision as to the precise time at which the opening into the air-tube must be made, but also the precise point at which the operation should be performed. These general questions I treat of in detail. The special indications may conveniently, but somewhat arbitrarily, be arranged as follows, in groups, which I have attempted to make complete, although some of the conditions, being purely surgical, do not strictly come within the compass of this essay: A. Acute inflammatory diseases of the larynx and trachea: 1. Acute oedema of the larynx. 2. Erysipelatous and exanthematous laryngitis. 3. Acute perichondritis, with abscess. 4. Diphtheritic croup. B. Chronic affections of the larynx and trachea: 1. Syphilitic laryngitis. 2. Phthisical laryngitis. 3. Chorditis vocalis inferior hypertrophica. 4. Carcinoma of the larynx or trachea. 5. Non-malignant growths of the larynx or trachea. 6. Tumors overlying the superior aperture of the larynx. 7. External compression of the trachea by tumors of the neck or chest. 8. Strictures of the larynx or trachea. C. Neurotic diseases: 1. Paralysis of the abductors of the vocal cords. 2. Spasm of the adductors of the vocal cords. {146} D. Traumatic conditions: 1. Foreign bodies in the larynx or trachea. 2. Impaction of foreign bodies in the pharynx or oesophagus. 3. Fracture of the larynx. Rupture of the trachea. 4. Scalds and burns of the larynx. 5. Incised and gunshot wounds of the throat. 6. Poisonous bites inflicted by certain insects about the mouth or neck. 7. Suffocation from the passage of blood, fluids, etc. into the air-passages (tracheotomy, with aspiration of the windpipe and artificial respiration). 8. Suffocation from the acute collection of either mucus or serum in the bronchia (ditto). 9. Suffocation from the inhalation or development of poisonous gases (tracheotomy, with artificial respiration). Finally, although it pertains alone to the province of the surgeon, I may allude to the temporary tracheotomy and "tamponing of the trachea" which has been recommended--and certainly found efficient--in preventing the entrance of blood to a dangerous degree into the lower trachea and lungs during the performance of certain operations in the neighborhood of or upon the air-passages, such as resection of the upper jaw, the extirpation of large nasal and naso-pharyngeal polypi, removal of the tongue, subhyoidean pharyngotomy, laryngotomy, and extirpation of the larynx.[1] [Footnote 1: For the details of this procedure consult Schüller, _Die Tracheotomie, etc._, Stuttgart, 1880.]