Uncured or too frequently repeated attacks of acute catarrh of the windpipe lead to chronic tracheitis, occasionally with considerable hypertrophy of the mucous membrane. In mild cases the cough and expectoration are less than in the acute disease, but persist, with exacerbations in cold, damp weather; in other cases the cough is more frequent, and the expectoration either thick, glutinous, and scanty, or else thin, frothy, or glairy, semi-transparent, and abundant. The separation by forcible paroxysmal coughing of accumulated adherent tough secretion from the tracheal mucous membrane has been observed to cause not only slight dyspnoea, but even the dangerous suffocating attacks of foreign bodies in the larynx. In color the sputa vary from gray to green and yellow; occasionally they are streaked with blood; sometimes they are without taste or odor; sometimes they are nauseous and fetid. Frequently patients with chronic tracheitis complain of "a sort of tightness at the root of the neck." In some cases a sense of dryness in the region of the trachea is the principal or the only symptom complained of, and this may alternate with, or even actually coexist with, occasional hypersecretion of tracheal or bronchial mucus. In chronic bronchitis and senile pulmonary emphysema mucorrhrea and cough usually depend to some extent upon the chronic tracheitis that is present. PATHOLOGY AND MORBID ANATOMY.--The pathological characteristics of simple tracheitis are hyperæmia, active or passive, swelling, and increased secretion of mucus. There is no fibrinous exudation. Acute inflammation causes the mucous membrane to become softened, swollen and red, either uniformly or in points or patches, frequently with ecchymoses and catarrhal erosions, more perceptible in the lower than in the upper portions of the trachea. Scanty secretion sometimes lies upon the surface in pearl-like drops, which might be mistaken for solid elevations only that they can be wiped off. In chronic inflammation the redness is more dull, reddish-blue or grayish; the secretion, sometimes more scanty and sometimes more abundant, is puriform and usually spread out over larger portions of the surface; and the glands are enlarged and prominent, with their ducts so dilated that their mouths are readily visible, sometimes, to the naked eye, and always with a low-power lens, and the rest of the tissue is hypertrophied, especially at the back wall of the trachea. Catarrhal tracheal ulcers are exceedingly rare, superficial, and of but slight extent, but they do occur, and are usually situated on the intercartilaginous membrane.