CHRONIC PHTHISIS. 



353 



Chronic Phthisis. 



Chronic phthisis is the common form of pulmonary tuber- 

 culosis. The primary lesions are generally found in the apices 

 of the lungs. In the great majority of cases the inspired air 

 is the source of the infection, though occasionally without 

 doubt the tubercle bacilli are introduced through the blood or 



FIG. 157. 



K 'Mig-r 



mm v 



Wall of a tubercular cavity, c, cavity ; k, cheesy wall ; c', c", small recent cavi- 

 ties ; t, tubercle. To the left, fibrous tissue in which are, 6, bronchi ; g, vessels. 

 X 100 (Schmaus). 



lymph channels the further extension of the disease result- 

 ing from rupture of a caseous focus into a bronchus and aspira- 

 tion of the infected material into other parts of the lungs. 



The lungs are firmly adherent to the chest-wall ; the pleural 

 cavities may be thus entirely obliterated. The pleurae are 



23 Hist. 



