256 BACTERIOLOGY. 



inoculation ; by direct injection into the circulation ; 

 by injection into the peritoneal cavity ; by feeding of 

 tuberculous material ; by the introduction of the bacilli 

 into the air-passages, and by inoculation into the an- 

 terior chamber of the eye. 



In the human subject the most common portals of 

 infection are, doubtless, the air-passages, the alimentary 

 tract, and cutaneous wounds. When introduced sub- 

 cutaneously the resulting process finds its most pro- 

 nounced expression in the lymphatic system. The 

 growing bacilli make their way into the lymphatic 

 spaces of the loose cellular tissue, are taken up in the 

 lymph stream and deposited in the neighboring lymph- 

 atic glands. Here they may remain and give rise to 

 no alteration further than that seen in the glands them- 

 selves, or they may pass on to neighboring glands, and 

 eventually be disseminated throughout the whole lymph- 

 atic system, ultimately reaching the vascular system. 



When having gained access to the bloodvessels, the 

 results are the same as those following upon intra- 

 vascular injection of the bacilli, namely : general tuber- 

 culosis quickly follows, with the most conspicuous pro- 

 duction of miliary tubercles in the lungs and kidneys, 

 less numerous in the spleen, liver, and bone marrow. 



When inhaled into the lungs, if conditions are favor- 

 able, multiplication of the bacilli quickly follows. With 

 their growth they are mechanically pressed into the tis- 

 sues of the lungs. As multiplication continues some are 

 transported from the primary seat of infection to healthy 

 portions of the lung tissue, there to give rise to a further 

 production of the tubercular process. 



In the same way infection through the alimentary 

 tract is in the main due to mechanical pressure of 



