THE EESPIEATOEY TEACT. 725 



while later even the elastic fibers are destroyed by liquefaction of 

 their basis-substance. The most characteristic feature of this 

 condition is the absence of blood-vessels within the tubercle. In 

 injected specimens we observe a small number of capillaries 

 entering the most peripheral zone of the tubercle, while around 

 it the blood-vessels remain intact, and simply overlap the nodule. 

 In its neighborhood emphysematous alveoli are often found. 

 (See Fig. 325.) 



With higher amplifications of the microscope we notice in the 

 tubercle a mass of inflammatory corpuscles with an extremely 

 delicate myxomatous reticulum. The corpuscles are character- 





FIG. 324. CIRRHOSIS OF THE LUNG, CAUSED BY SUBACUTE 

 TUBERCULOSIS. BLOOD-VESSELS INJECTED. 



A, com pressed alveolus ; I, acute inflammatory infiltration of the interstitial tissue ; F, 

 newly formed, fibrous (cicatricial) connective tissue ; C, scanty blood-vessels. Magnified 

 500 diameters. 



ized by a fine granulation i. e., they are supplied with a little 

 living matter only. In the central portions of the tubercle mul- 

 tinuclear bodies are often found, the origin of which is not fully 

 understood. 



(c) Plastic interstitial pneumonia consists in the new formation 

 of interstitial connective tissue, which leads to an enlargement of 

 the alveolar walls, with a decrease of the number of the blood- 

 vessels. This process is very common in insufficiencies of the 

 valvular apparatus of the heart and stenosis of the arterial ostia, 



