256 TUBERCULOSIS. 



form of dust in the air. In all probability every x^erson 

 living has breathed into his lungs very many of these 

 deadly little germs, but in perfect health they have done 

 no harm. The healthy mucus membranes of the air pas- 

 sage are covered with little arms or cilia, which are in 

 constant motion, and doubtless serve more than anything 

 else to prevent the lodgment of dust and bacilli there; 

 but any little patch of congested membrane or any spot 

 that has become denuded of its cilia by a cold or cough, 

 or other cause, may be pounced upon, and when 

 once the living bacillus has found a place to lodge, it 

 immediately multiplies and becomes a focus around 

 which myriads of baccilli form. These in time prey upon 

 the immediately surrounding tissues. As soon as they 

 have exhausted the material in the center of this area, 

 the bacilli dies and a cheesy degeneration takes place, and 

 we have a mass of small grayish miliary tubercles (so 

 called from their resemblance to the millet seed), with a 

 belt of living bacilli working their way into the surround- 

 ing healthy tissues. These in time die, for the life of the 

 bacillus is very limited, but under conditions favorable to 

 them the supply is always replenished. Then a few bacilli 

 are taken up by the circulation and carried to another part 

 of the organ, and another focus is established. At length 

 a number of these foci coalesce, and the degenerated 

 tuberculous mass suppurates and becomes broken down, 

 and the result is a lung cavity or abscess. 



Sometimes this process takes place very rapidly, and 

 a fatal termination is reached in a few weeks or months, 

 and then again it may continue on for years. There are 

 well authenticated cases where the process has to all ap- 

 pearances been entirely arrested, but where the germs 

 have laid latent in the system for many years and sud- 

 denly broken out in its most virulent form. The ma- 

 terial coughed up by persons suffering from consump- 

 tion contains these germs often in enormous numbers. 



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