TUBERCULOSIS. 445 



Softened infiltrations are usually bounded by thin, yellow, 

 sinuous layers of tissue. In the vicinity the lung usually ap- 

 pears in the state of flabby, red hepatization, saturated with a 

 viscid exudate, and at other times it is moderately indurated. 

 The softening of the infiltrations also terminates in the forma- 

 tion of cavities, and the ulcerative destruction of the lungs. This 

 variety of tuberculous phthisis differs from that described before 

 only in form and acuity, but not in any essential point, nor in 

 its terminations. 



Sometimes, scattered or clustered nodules and infiltrations 

 fill a district or the larger portion of a lobe so entirely that 

 this becomes rigid, fragile, and, in part, atelectatic. In such 

 cases, we may speak of a pneumoniform, subacute tuberculosis, 

 whose features are sufficiently marked to distinguish it from 

 catarrhal or " desquamative" pneumonia. If a group of nodules, 

 or an infiltration lying close to the pleura, is. disintegrated, and 

 the pleura destroyed by ulceration, perforation into the pectoral 

 cavity may follow. This is the most common cause of pneumo- 

 and pyo-pneumothorax, which not infrequently accompany tuber- 

 culosis of the lungs. 



In looking over the second form of tuberculosis of the lungs f 

 we again are satisfied that there is no essential difference between 

 a nodule and an infiltration ; that either may be transformed into a 

 crumbly mass and become softened. The next step i. e., ulcera- 

 tion of the lung-tissue is different only in its acuteness ; that is r 

 according to whether a number of scattered nodules are breaking 

 down at different times, or whether an infiltration is continually 

 softened and simultaneously increases in size at its periphery. The 

 surrounding lung-tissue, in all forms of softening and local necrosis, 

 is evidently involved only in a secondary manner, therefore is in a 

 " re-active," acute, or chronic inflammation. 



The third form of tuberculosis of the lungs is comparatively 

 rare ; it is called tuberculous pneumonia, pneumonia tuber culisans. 

 In the description of subacute tuberculosis, I have already men- 

 tioned that lobules, in flabby hepatization, are sometimes the 

 points where tuberculous nodules or infiltrations are formed. 

 Should this grayish-red or gray hepatization involve a number 

 of lobules, or nearly the whole of a lobe, the features of lobular 

 pneumonia arise. It becomes tuberculous by the appearance of 

 gray and grayish-yellow nodules, or of gray and grayish-yellow 

 infiltration, either in the neighborhood of bronchi or at the 

 periphery of the lobules, or scattered throughout them. In the 



