THE RESPIRATORY SYSTEM. 



511 



new-formed tissue may undergo necrosis and ulceration so that with an 

 advancing consolidation of the lung tissue about the bronchi numerous 

 larger and smaller, rough, irregular cavities may be formed (Fig. 291). 

 The walls of the larger bronchi also may become the seat of a tubercu- 

 lous inflammation with more or less necrosis (Fig. 292). Ulceration 

 of these necrotic bronchial walls may lead to the formation of ragged 

 cavities (Plate IX. and Fig. 293). 



The secondary development of dense fibrous tissue in connection with 

 tuberculous broncho-pneumonia is a marked feature of the persistent or 

 chronic forms. Tuberculous broncho-pneumonia is one of the most im- 



FIG. 293. TUBERCULOUS BRONCHO-PNEUMONIA. 



Showing the formation of cavities in the lung in acute phthisis. To the right are small, in the centre 

 large tuberculous bronchiectatic cavities. At the left are areas of tuberculous consolidation with caseation 

 in their central portions. 



portant of that complex of pulmonary lesions called phthisis, and is com- 

 monly associated with other forms of tuberculous involvement of the 

 organ miliary tubercles, larger areas of consolidation, etc. 



COMPLEX FORMS OF NODULAR AND DIFFUSE TUBERCULOUS LESIONS. 



(Phthisis.} 



With or without the various well-defined forms of tuberculous bron- 

 cho-pneumonia and miliary tubercles above described, there may be 

 more or less circumscribed small or large areas of productive and exuda- 

 tive tuberculous inflammation of the lung with necrosis, both of the lung 

 tissue, the new-formed tissue, and the exudate (Plate XII. ). These may 



