258 CLINICAL BACTERIOLOGY. 



of the lungs. The frequency of occurrence of other forms 

 of tuberculous disease falls far behind that of involvement 

 of the lungs. The next most important portal of entry is 

 the digestive tract, which plays an important role especially 

 in the etiology of tuberculosis in early life. Under these 

 conditions the infection gives rise, on the one hand, to 

 swelling of the cervical lymph-glands, often with conse- 

 quent suppuration (scrofulosis), and on the other hand 

 and more frequently without primary involvement of the 

 intestine to caseation of the mesenteric glands, or to 

 chronic peritonitis. In adults the digestive tract is rela- 

 tively seldom the portal of entrance for tubercle-bacilli, 

 which in that event give rise to ulcerative processes in the 

 intestine. Breaches in the continuity of the skin constitute 

 a third and not at all uncommon medium of infection with 

 tubercle-bacilli. Cases of cutaneous tuberculosis and of 

 tuberculosis of wounds have in recent years been reported 

 in considerable number. The so-called postmortem tubercle 

 must be included in this category, as careful investigation 

 has shown. Further, the relationship of lupus to tubercu- 

 losis is -scarcely any longer a matter of serious doubt. 

 Koch has succeeded in isolating tubercle-bacilli in pure 

 culture from lupus-nodules. 



The Pathogenic Activity of the Bacilli in the Hu- 

 man Body. The most characteristic product of tuber- 

 cle-bacilli is the tubercle. In this the bacilli lie mainly 

 within the interior of the giant-cells, partly at the center, 

 partly at the periphery ; but the bacilli are to be found also 

 in and among the round cells constituting the tubercle. 

 At times the rods within the giant-cells appear not to be 

 distinctly stained, but disintegrated. MetschnikofF considers 

 such appearances as the remains of tubercle-bacilli, and, in 

 consequence, believes the giant-cells to be phagocytes. 

 The specific nodules persist only for a short time, and soon 

 disintegrate into cheesy-necrotic material. 



Besides giving rise to the formation of nodules, the 

 tubercle-bacilli exhibit varied other pathogenic activity. 

 At times they give rise to serous, purulent, or hemorrhagic 

 inflammation, and in rare cases even to fibrinous exudation. 

 They may further cause cheesy-necrotic inflammation 

 without the previous formation of nodules. In some cases 

 the inflammation caused by the bacilli has from the begin- 

 ning a tendency to the formation of connective tissue, so 



