the blood (as by giving alkaline mineral waters to drink, etc.) has received a new and direct support by Rossbach's recent observations of diminution of the blood-supply and of the secretion in the tracheal mucous membrane of cats whose blood was made alkaline by injecting sodium carbonate into the femoral vein. Patients subject to tracheitis should observe all the precautionary measures of so-called bronchitics as to sponging, bathing, and friction of the body, wearing a respirator, clothing, exercise, habits, etc. Complicated Tracheitis. Under this heading are here classed together all inflammatory conditions of the windpipe differing from simple or catarrhal tracheitis. In these, other tissues may be affected as well as the mucous membrane. In exanthematous, erysipelatous, and exudative tracheitis the mucous membrane is prominently involved; in oedematous and phlegmonous tracheitis, the submucous connective tissue; and in perichondritic and chondritic tracheitis, the cartilages and their investing membrane. The latter forms are connected with suppurative and ulcerative processes, and, unless traumatic, almost never occur, except in phthisical and syphilitic tracheitis. I shall speak of them under the head of Ulceration. The tracheitis of measles and scarlatina consists in an acute catarrh, with sometimes considerable desquamation of epithelium, erosion, and capillary hemorrhage. In cases of small-pox in which the larynx is affected, the same disease may extend into the trachea, varying in severity from a congestion of the mucous membrane to an intense pustular process. Erysipelas of the larynx may also involve the windpipe, and when it does is exceedingly dangerous. More than half a century ago Gibson observed in an epidemic of erysipelas that when it spread to the trachea it generally proved fatal.[1] Tracheal oedema is extremely rare even when the larynx is oedematous. Phlegmonous inflammation and abscess have been observed in a few instances. Tracheal diphtheria is usually an extension of diphtherial disease of the larynx. Without entering into a discussion of the nature and cause of diphtheria, as either a local or general disease, it is here sufficient to refer to the fact that while in simple inflammation of mucous membrane no fibrinous exudation takes place, certain poisonous irritations lead to the exudation of lymph which infiltrates the tissue and may form a pseudo-membranous deposit upon it: experiments have proved that ammonia, chlorine, and, certainly, bacteria, are able to produce this. In laryngo-tracheal diphtheria or croup the disease most frequently commences in the pharynx, occasionally in the larynx, and much more rarely in the trachea. [Footnote 1: _Transactions of the Edinburgh Medico-Chirurgical Society_, vol. iii., 1828.] The treatment of each of these forms of complicated tracheitis is the same as the treatment of the corresponding form of laryngitis. ULCERATION.