THE RESPIRATORY SYSTEM. 



509 



TUBERCULOUS BRONCHO-PNEUMONIA. 



In another most important phase of tuberculous inflammation of the 

 lung there is an involvement of the walls of the smaller bronchi and the 

 associated groups of air spaces. This may occur through inhalation of 

 bacilli or by their aspiration from an established tuberculous focus, for 

 example, from a lesion at the apex, or, as is often the case in children, 

 from tuberculous bronchial lymph-nodes ; or infection may take place 

 through the blood- or lymph-vessels. In the early stages of tuberculous 

 broncho-pneumonia the cut surface of the fresh lung may present small 

 gray or yellowish-white areas of consolidation with necrosis clustered 

 about the small or terminal bronchi (Plate V.). The process is at first 



FIG. 290. TUBERCULOUS INFLAMMATION OF THE LUXG WITH CHEESY DEGENERATION ABOUT THE 

 BRONCHI IN A SINGLE LOBULE OF THE LUNG TUBERCULOUS BRONCHO-PNEUMONIA. 



largely exudative, involving a catarrhal and necrotic inflammation of the 

 mucous membrane of the bronchus with more or less exudate which also 

 may soon become necrotic in the associated groups of air spaces (Fig. 

 290). Sometimes organized tubercle tissue may form in the walls of 

 the bronchi with thickening of the walls and obliteration of the blood- 

 vessels of the adjacent air spaces. 



By the extension of the process from one and another affected bron- 

 chus and the coalescence of these, large areas of the lungs may become 

 involved. In this more advanced stage of broncho-pneumonia the larger 



