PULMONARY TUBERCULOSIS 235 



177. Pulmonary Tuberculosis. — Pulmonary tuberculosis 



is a disease located in the lungs. The cause is ;i definite 

 plant with parts and habits which are easily recognized by 

 bacteriologists (students of bacteria). This plant is called 

 Bacillus tuberculosis, and was proved to be the cause of 

 consumption, or tuberculosis, by Robert Kocli, a German 

 scientist, in 1882. These tuberculosis bacteria, or germs, 

 in countless numbers are found leading a parasitic life in 

 the lungs of a tubercular patient. The bacteria are ex- 

 tremely minute, and can be seen only by the use of a 

 microscope of high power. 



The large number of germs in the lungs grow rapidly 

 and they are set free in the air by coughing. One tuber- 

 culosis patient may give off millions of these germs in a 

 day. For this reason great care should be taken in destroy- 

 ing the sputum of patients, for if the germs become dry. 

 they are carried about as dust particles. 



Tuberculosis and other disease germs are so numerous 

 that it is impossible to escape taking some of them into our 

 bodies, but they usually do us no harm unless we are in a 

 weakened condition. 



Modern methods of cleaning the streets by flushing witli 

 water, keeping garbage covered, and wiping up tin- dust 

 in our homes instead of using the old-fashioned feather 

 duster are doing much to keep down the number of germs 

 in the air which we breathe. 



The bacteria that are breathed in from the air may find 

 some weak place in the lungs in which to take up their 

 parasitic lives. Those which enter on the food pass from 

 the digestive tract into the blood and are eventually carried 

 to the lungs. The introduction of tuberculosis germs in 

 this way is especially frequent in children. In many 

 cases milk from tuberculous cows is the source of the 

 disease germs. See § 248, page 34 ( .*. 



