724 TEE RESPIRATORY TRACT. 



fibrous capsule. Thus the cheesy focus is encysted, and may be 

 rendered innocuous by fatty metamorphosis and subsequent cal- 

 cification. 



Saturation of the cheesy focus with a sero-albummous exu- 

 date from the surrounding inflamed tissue will lead to the 

 formation of a tuberculous cavity, the size of which will at first 

 correspond with that of the original cheesy focus, while after- 

 ward the cavity becomes enlarged by similar inflammatory 

 changes in the surrounding capsule itself, which result in the 

 formation of cheesy foci, presenting all the appearances minutely 

 described in the chapter on tuberculosis. 



A complete cure of the tubercle is effected by a profuse new 

 formation of connective tissue in its neighborhood, with the 

 result of a dense, fibrous, cicatricial callosity. This termination 

 of the original catarrh al pneumonia is known by the term cirrhosis 

 of the lung. Large portions of lung-tissue, usually of the apices, 

 are thus transformed into solid fibrous connective tissue, more 

 or less pigmented, according to the amount of pigment present 

 in the lung- tissue before the start of inflammation. In the cal- 

 losity are inclosed compressed alveoli of the lung and cheesy 

 foci in a more recent process, and calcareous nodules in an older. 

 The latter represents, as a matter of course, a cure. The cal- 

 losity is always marked by scanty vascularization. If, on the 

 contrary, a new inflammation ensues in the callosity subacute 

 tuberculosis with a complete loss of the blood-vessels in a cer- 

 tain portion, this will become a tubercle, and the process will, 

 though slowly, advance to destruction of the lung-tissue. This 

 is the reason why, in cirrhotic portions of the lungs, all stages 

 of tuberculosis may be found, both those tending toward a 

 cure and those tending toward ulcerative destruction. (See 

 Fig. 324.) 



Acute miliary tuberculosis is an inflammatory process, just as 

 is chronic tuberculosis. No positive proofs have yet been fur- 

 nished that miliary tubercles originate from embolism of vascu- 

 lar districts of the lung-tissue, although such an embolic process 

 is highly probable. In the earliest stages of the formation of a 

 miliary tubercle we observe all the characteristic features of 

 catarrhal pneumonia. The smallest so-called sub-miliary tubercles 

 are inflammatory foci, involving only a few alveoli ; while larger 

 tubercles originate from a coalescence of a number of solidified 

 alveoli. In the early stages of the inflammatory infiltration the 

 elastic fibers of the alveoli mark the boundaries of the alveoli, 



