TUBERCULOSIS 93 



As already said, however, tuberculosis of the lung is by 

 far the most frequent form of infection. In seeking 

 to prevent the infection of others, therefore, it is im- 

 portant that the consumptive be carefully instructed to 

 always spit into a vessel containing some disinfectant, or 

 into a paper sputum cup which can be burned each 

 day. In coughing, the scattering about of droplets 

 of sputum should be prevented by holding a paper 

 handkerchief in front of the mouth. The consump- 

 tive's room should contain no unnecessary furniture, 

 bric-a-brac, hangings, or other objects likely to catch 

 dust. Remembering that drying and sunlight are 

 potent in the destruction of bacteria, it follows that 

 the maximum of air and sunshine should be provided. 

 Dry sweeping should not be permitted, dust should al- 

 ways be wiped up with a rag dampened with crude oil. 

 From what has been said concerning the bacteriology of 

 tuberculosis, other precautions will suggest themselves. 



When tubercle bacilli are grown for a time in glycerin 

 beef-broth, they gradually cause the broth to become 

 loaded with poisons. When such a broth culture is 

 evaporated and filtered, so as to be entirely free from 

 tubercle bacilli, we have what is known as tuberculin. 

 A curious thing about this tuberculin is that when 

 minute quantities are injected into an individual in- 

 fected with tuberculosis, a characteristic reaction takes 

 place, marked by fever, prostration, some pains, in- 

 creased cough, etc. In a normal, uninfected individual 

 no such reaction is produced. This tuberculin reaction 

 is thus of diagnostic value. It can also be applied by 

 scarifying the skin with a needle and rul)bing a droj) of 

 tuberculin into the scarifications. A positive reaction 



