BACTERIA AND DISEASE 323 



bility of his infecting others and give as little opportunity 

 as he can for the transfer of his affliction. The term cold 

 is loosely applied to a number of infections which vary 

 greatly in their severity. Colds often pave the way for 

 tuberculosis, pneumonia and other ills, and they should 

 be treated with promptness and vigor when first contracted, 

 otherwise they are much more difficult to deal with. 



Tuberculosis, one of the most frequent causes of death, 

 is a disease that may attack any part of the body, although 

 it most commonly affects the lungs when it is known as 

 consumption. It was proven by Robert Koch, a famous 

 German bacteriologist, to be caused by a small rod-like 

 organism, the Bacillus tuberculosis. Cattle are commonly 

 affected with a form of tuberculosis and the bacilli fre- 

 quently occur in milk. Much effort has been made to 

 stamp .out the disease in cattle, and milk that is sold in 

 cities is often put through a process called pasteurization 

 in order to kill the germs of tuberculosis or other disease 

 germs that may be contained in it. It is now recognized 

 that tuberculosis may be conveyed from one person to 

 another. This may be done by the hand-to-mouth 

 method previously described, but a frequent source of 

 infection consists in breathing air laden with tubercle' 

 bacilli. Air in dwellings occupied by consumptives is 

 particularly dangerous, especially if it contains much dust. 

 The sputum of consumptives usually abounds in bacilli, 

 and when dried and reduced to powder it may be readily 

 blown about in the air and taken into the lungs. Con- 

 sumptives should be particularly careful not to expectorate 

 in places where their dried sputum can possibly be a 

 source of infection. The sputum should be disposed of in 

 receptacles especially devised for the use of consumptives. 

 Care should be taken, when coughing or sneezing, to 

 cover the mouth or nose with a handkerchief, and the 



