TUBERCULOUS BRONCII0 PNEUMONIA. in this form of tubereulous infection of the lungs, the tuberculous areas occur in the walls of the small er bronchi and in the contiguous lung tissue. In its early stages the inflammation is mostly catar rhal, there being a more o• less extensive exudate into the affected bronchi. As more and more bronchi are affected, there is frequently a coales cence of adjacent areas, with the formation of quite large masses of consolidation. These break ing; down form cavities. The progress of the affection may be slow o• rapid. and is one of the forms of pulmonary tuberculous popularly called The term 'phthisis' is also applied to diffuse exudative tuberculous inflammation of the lungs, which may he either acute or chronic. In the acute form extensive areas of lung tissues may be involved, become consolidated, and, undergoing necrosis, result in the formation of large cavities. In the chronic form there is a slower involvement of the lung tissues, and there is apt to be more fibrous tissue, especially in the walls of cavities. These cavities may be small or large; are usually at first devoid of any wall, but soon acquire a wall of fibrous tissue, often lined with new tu bercle tissue or with granulation tissue. This lining tissue often contains enormous numbers of tubercle bacilli, which are cast off in the sputum. It also furnishes a lodging place for pyogenic cocci, which cause suppuration of the membrane, and it is not at all improbable that these pyo genic cocci are very largely concerned in the for mation of the cavities themselves. This secondary
or concurrent infection, as it is called, is also largely responsible for the bronchitis and yellow or greenish expectoration which so usually ac companies phthisis. Blood vessels stretch across these cavities or lie exposed in their walls, to be broken either by an extension of the disease itself or from a strain too sudden for their weakened walls. In this way may be caused the hemor rhages so frequently associated with phthisis.
The most frequent site of tubercles in the adult lung is the apex, although the initial lesion may occur in any part of the organ. In children the bronchial lymph nodes are usually first affected. `Healed tubercles' of the apex are found in a large proportion of autopsies.
Associated with the lesions in the lungs may be lesions in other parts of the body. These may be secondary to the pulmonary infection or the lung lesion may be secondary to other lesions. Acute or chronic inflammation of the pleura com monly accompanies the disease of the lung tissue proper. This inflammation may be simply exu dative or may be tuberculous. Infection with the pyogenie cocci sometimes results in an empyceina (purulent pleurisy) ; or the opening up of bronchi or air spaces into the pleura may result in a pneumo-thorax.