Diseases of texture occur in all the tissues entering into the composition of the air-passages, but especially in the mucous membrane, which is the primary seat of disease in by far the greatest number of cases and in the greatest variety of form. Hence its diseases claim the most particular attention. They frequently extend to the subjacent tissues, and, for the most part, lead to their destruction.

A. Diseases Of The Mucous Membrane And Of The Subjacent Areolar Tissue. A. Hyperemia And Anosmia

Hyperemia of the air-passages is of comparatively common occurrence. When seated in the finer bronchial ramifications, it is combined with hyperemia of the parenchyma of the lung; but in the larger bronchial tubes, and in the trachea and larynx, it usually exists alone, and independently of that affection. Hyperemia varies extremely in importance, according as it is active, or simply mechanical and dependent on an obstructed circulation, or passive, which is a more rare affection; constituting, in any case, an independent disease, which finally gives rise to hemorrhage, or, under other conditions to stasis, and thus to acute or chronic inflammation. To the first belong the hemorrhages from the mucous membrane of the bronchi, trachea, larynx, and epiglottis. On examining the dead body, we find the air-passages to a certain degree filled with coagulated or fluid blood, and patches of the mucous membrane swollen, of a dark-red color, bleeding when pressed, and apparently loosened in texture; we find no other source of hemorrhage, no pulmonary apoplexy, nor mechanical or ulcerous separation of continuity. The lungs, as we find in other hemorrhages from the air-passages, present a dark or light-red speckled appearance from the deposition of blood in the terminations of the bronchial tubes and in the air-cells; but at the same time are (elsewhere) emphysematous, swollen, and pale, in consequence of the obstructed condition of the bronchial tubes, and the impediment thus presented to free expiration.

These hemorrhages occur in the active form during the period of evolution, and when there is general plethora, as vicarious to menstrual and hemorrhoidal fluxes. They arise from and accompany the congestions which so frequently precede the development of tubercles in the lungs, and may be produced by any strong exertion, but especially by the overtaxing of the respiratory organs. They may arise from any sudden shock to the lungs, from the sudden rarefaction of the atmosphere, and they are very frequently dependent on mechanical hyperemia, resulting from hypertrophy and dilatation of the heart.

Anosmia of the mucous membrane of the air-passages is more or less developed in senile and other varieties of atrophy.