THE STORY OF THE BACTERIA. 



one way or another, gain access to the body. 

 When there, if the conditions are favorable, 

 they tend to grow, and as they do so there 

 form about them little masses of new tissue, 

 which are called tubercles. The most common 

 seat of the disease is the lungs, but it may oc- 

 cur in any part of the body. 



It is not necessary for our purposes to enter 

 further into the details of the progress of the 

 disease. It is but too well known to nearly 

 every one who has seen one and another pass 

 away from sight under its insidious progress. 

 It is our purpose here only to show how the 

 disease is commonly acquired. 



Not all persons are equally liable to be at- 

 tacked by tuberculosis. There seems to be a 

 certain condition of the body cells which pre- 

 disposes to the disease, and this predisposition 

 is in the most marked degree hereditary. We 

 do not know yet in what this predisposition 

 consists. We believe that when the tubercle 

 bacillus gets into the healthy body the cells of 

 the part in which it lodges in some way tend 

 to resist its growth, or afford unfavorable con- 

 ditions for its development. The temporary 



