TUBERCULOSIS. 443 



puration ensue on the inner surface of the capsule, which is 

 freely vascularized, the pus mingles with the former contents, and 

 a thin, serous pus results, which contains a number of friable 

 particles. This is the so-called tuberculous pus. At length the 

 entire mass becomes softened, and the formation of a cavity fol- 

 lows, which is inclosed by a capsule and is therefore a closed 

 abscess. The cavity may be completely surrounded by lung-tis- 

 sue, thus producing the so-called parenchymatous cavity. If a 

 cavity arises from a bronchus by a formation of tubercles in its- 

 mucous lining, or if perforation takes place into one or more 

 bronchi, a bronchial cavity is formed, which result must follow 

 after a certain size of the cavity is reached. By this means, the 

 expectoration of the contents becomes possible, and, also, the 

 access of atmospheric air to the contents of the cavity. 



The walls between two or more cavities may be perforated by 

 ulcerations, due to a continuous or repeated formation of tuber- 

 cles. Lastly, a cavity may arise from the confluence of a number 

 of cavities, of sizes varying from that of a walnut to that of the 

 fist of a child or the fist of a man, the walls being formed by 

 lung-tissue, which is partly callous, partly sinuous and corroded. 



I would mention, incidentally, that not infrequently the cav- 

 ity is traversed by firm cords of different sizes, and the walls 

 thickly set with such formations. These are the remains of the 

 former blood-vessels of the lung, which, by thickening of their 

 adventitial coat, have become callous, and resisted the process 

 of ulceration. Sometimes, as is well known, a tuberculous nod- 

 ule, imbedded in the adventitia, may disintegrate before oblit- 

 eration of the vessel, and, in consequence of the ulcerative 

 destruction of the wall, a profuse or fatal haemorrhage may 

 ensue. 



Finally, it. may happen, perhaps, under the influence of 

 the penetrating air, that a rapid ulcerative destruction invades 

 large portions of the wall of the cavity, which becomes necrosed 

 and, together with the neighboring tissue, passes into gangrene. 

 Then we find the cavity bordered by lung-tissue, of a grayish or 

 brownish-green color, eroded and containing irregular sinuses, 

 while its contents are an offensive, putrescent ichor, mixed with 

 blood, pus-flakes, and cheesy crumbs. These characteristics cor- 

 respond to the tuberculous phthisis of Laennec. This term may 

 be employed if we understand by it the ulcerative destruction 

 of the lung-tissue, and if, by the addition of " tuberculous/ 7 we 

 designate the nature of the destruction. 



