The Cause and Prevention of Tuberculosis 319 



tuberculosis, however, is that of the lungs, known generally 

 as " consumption." Thus when we speak of tuberculosis, we 

 usually mean consumption. 



497. How the Germs of Consumption do their Work. The 

 presence of the tubercle bacillus in the body does not always 

 cause consumption. 



When the germs of 

 this disease get into 

 the body, a contest 

 seems to take place 

 between these germs 

 and the cells of which 

 the body is composed. 

 If the germs gain the 

 victory, little tumor- 

 like knots, not unlike 

 the tiniest grains of 

 sand, called tubercles, 

 are formed. After a 

 time these tubercles 

 in the lungs soften 

 and break down. 

 The matter of which 

 they are composed 

 is coughed up into the mouth and is known as sputum. 

 This matter thus coughed up often contains millions of 

 tubercle baccilli and is therefore dangerous to the health of 

 other .people. It has been estimated that in the sputum 

 of one consumptive there may be more than twenty-four 

 millions of these germs in the course of twenty-four hours. 



498. How Consumption is regarded as a Contagious Dis- 

 ease. We must remember that consumption is not contagious 

 in the sense in which we speak of scarlet fever, smallpox, 



FIG. 171. Germs of Tuberculosis. 



(A minute portion of sputum from a case of phthisis, 

 or consumption, magnified 1000 diameters. These 

 germs are rod-shaped bacteria, stained to show 

 black. The black spots in the figure are merely 

 the debris in the sputum, also stained to look black.) 



