3o8 



Specific Inflammations. 



ever the point of infection may escape involvement provided the 

 tubercle bacilli are rapidly carried onward by the lymph, under 

 which circumstances the tuberculous inflammation may first show 

 itself in the lymph glands. After feeding tuberculous material to 

 hogs the mucous membrane of the intestine is uniformly unaffected 

 and the disease primarily occurs in the mesenteric lymph nodes. 

 [Ravenel has produced a similar primary involvement of the lymph 

 nodes of the mesentery in dogs by feeding the tubercle bacilli 

 rubbed up in butter, having previously starved the experiment ani- 

 mal for a time.] After being taken up by the chylous vessels the 

 tuberculous virus passes into the blood by way of the thoracic duct 

 and thence into the lungs, and after traversing the lesser circulation 

 is carried to all of the organs. The different organs do not all show 



wm^^ 



Fig. 71. 

 Portion of lung of horse showing miliary tubercles and tuberculous infiltration. 



a uniform predisposition to the influences of the bacilli, that is, 

 they do not all offer equally favorable conditions for the nutrition 

 of the microorganisms. The lungs, lymph glands and especially the 

 general lymphatic tissues (bone-marrow, spleen), are places where 

 the bacillus most readily lodges. For this reason the lungs may 

 become the seat of the primary involvement after feeding tubercle 

 bacilli to an animal, and the existence of the pulmonary afifection 

 is by no means to be looked upon as indicating that infection took 

 place by inhalation. 



The primary, and in fact the only tuberculous focus may be en- 

 countered in the interior of bones, or in lymph glands or the tes- 

 ticle. In such instances isolated tubercle bacilli which have gained 

 access to the blood may have been caught and lodged in any such 



