BACTERIUM TUBERCULOSIS 439 



is in the main due to the bacilli being forced by mechanical 

 pressure into the walls of the intestines. Investigation has 

 shown that lesions of the intestinal coats are not necessary 

 for the entrance of tubercle bacilli from the lumen of the 

 gut into the internal organs and tissues. They may be 

 transported from the intestinal tract into the lymphatics 

 in the same way that the fat-droplets of the chyle find 

 entrance into the lymphatic circulation. 



They may gain access to the tissues by way of the tonsils. 



Unlike most pathogenic organisms, the tubercle bacillus 

 is resistant to drying. When thrown off from the lungs in 

 the sputum of tuberculous patients, unless special precau- 

 tions be taken to prevent it, the sputum becomes dried, is 

 ground into dust, and sets free in the atmosphere the 

 tubercle bacilli which came with it from the lungs, and which 

 have the property of exciting the disease in susceptible 

 persons who receive them into the nose and throat. 



Location of the Bacilli in the Tissues. The bacilli will be 

 found most numerous in those tissues in which the disease 

 is most active. 



In the initial stage of the disease the bacilli will be fewer 

 in number than later; at this time only scattered bacilli 

 may be found; later they are more numerous; and, finally, 

 when the process has advanced to a stage easily recognizable 

 by the naked eye, ,they are distributed through the granula- 

 tion zones in clumps and scattered about in large numbers. 



In the central necrotic masses, which consist of cell- 

 detritus, it is rare that the organisms can be demonstrated 

 microscopically. It is at the periphery' of these areas and 

 in the progressing granular zone that they are to be seen 

 most frequently. 



