MICROORGANISMS AND HUMAN WELFARE 



31 



tuberculosis, which is more commonly known as consump- 

 tion. In New York City alone the Board of Health reports 

 300 to 400 new cases every week. Yet if the general public 

 only knew the manner in which this disease is transmitted 

 and would make use of this knowledge, the dreadful sacrifice 

 of life and health due to this " great white plague " could be 

 almost wholly prevented. 



It was conclusively proved in 1882 by Dr. Koch, a noted 

 German scientist (Fig. 13), that tuberculosis is always caused 

 by extremely small, rod-shaped bacteria, bacillus tuberculosis 

 (Fig. 14) . He found countless numbers of these living germs 

 in the sputum coughed up 

 by consumptive patients; 

 he cultivated these germs 

 in test tubes and when he 

 injected the bacteria into 

 the bodies of guinea pigs 

 or rabbits, the animals be- 

 came ill with tuberculosis. 

 By many experiments of 

 this sort, biologists have 

 learned important facts in 

 regard to the cause, preven- 

 tion, and cure of disease. 



We are absolutely sure 

 then, that before any one 

 can become a consumptive, he must take into his body the 

 living bacteria of consumption, and the most common avenue 

 of infection is through the nose and air passages. Consump- 

 tives who are ignorant of the danger they are causing, fre- 

 quently expectorate on the floors of rooms or of public con- 

 veyances, and when this sputum becomes dried, the germs 

 are likely to be blown about in the air, and to be inhaled by 



FIG. 14. Tuberculosis bacteria in human 

 sputum. (Courtesy of Dr. Thomas S. 

 Carrington.) 



