[Footnote 1: Such a case has been positively reported, or I would deny the possibility of its occurrence.] ETIOLOGY.--Laryngeal oedema is seldom, if ever, idiopathic. Usually it accompanies or follows either some disease or injury of the larynx[2] or neighboring structures or a constitutional affection. Acute oedema may be caused by catarrhal or diphtherial pharyngo-laryngitis; irritation from scalds, burns, caustics, foreign bodies (especially sharp ones), or other trauma; laryngeal ulcers, especially syphilitic and tuberculous; laryngeal perichondritis, tonsillitis, parotitis, or inflammation of cervical tissues on the one hand, and pyæmia and septicæmia, endocarditis, erysipelas, small-pox, scarlatina, measles, typhoid fever, typhus, or acute Bright's disease of the kidneys on the other. "It has ensued upon deglutition of very cold water and upon prolonged vocal efforts" (Cohen). Perichondritis and chondritis, tuberculous, syphilitic, carcinomatous, or typhoid ulcerations of the larynx, especially when deep-seated or extensive, are sometimes attended with acute, but more often with chronic, oedema. Non-inflammatory or chronic laryngeal oedema is sometimes part and parcel of general dropsy in consequence of heart, kidney, or lung disease: Horace Green has reported a case occurring in a man who had hydræmia from great losses of blood from hemorrhoidal tumors; and it is sometimes due to some impediment to free venous circulation in the laryngeal tissues, from paralysis of the walls of the vessels, mechanical obstruction, tumors of the thyroid body or in the mediastinum, etc. compressing the jugular veins, compression of the superior vena cava, etc. [Footnote 2: According to Sestier, who has written (in 1852) the most elaborate treatise extant on the subject, four-fifths of all cases occur in other laryngeal affections.] Cohen mentions cases to show that acute iodism and mercurialization may cause laryngeal oedema. He also says that although occurring in individuals in good general health, it is more apt to take place in those of impaired constitution or recently convalescent from acute diseases; and in some instances there would appear to be some peculiar predisposition toward its occurrence the nature of which is not understood, for examples are on record of more than one attack in the same individual. Under all these circumstances the immediate exciting cause, when apparent, seems to be exposure to cold and moisture. Laryngeal oedema is not a disease of childhood; exceptional under five years, it is very rare until after ten. Most cases occur between eighteen and thirty-five. After the sixtieth year it is again rare; and it occurs more rarely in women than in men.