PLANTS WITHOUT CHLOROPHYLL 



153 



openings, or through a 



break in the'skin. They 



may be carried by means 



of air, food, or water, 



but are usually trans 



mitted directly from the 



person who has the 



disease to a well per 



son. This may be done 



through personal con 



tact or by handling 



articles used by the 



sick person or by drink 



ing or eating foods 



which have received 



some of the germs. 



From this it follows 



that if we know the 



methods by which a 



given disease is communicated, we may protect ourselves from it 



and aid the civic authorities in preventing its spread. 



Tuberculosis. The one disease responsible for the greatest 



number of deaths perhaps one seventh of the total on the 



globe is tuberculosis. 

 It is estimated that of 

 all people alive in the 

 United States to-day, 

 5,000,000 will die of 

 this disease. But this 

 disease is slowly but 

 surely being overcome. 

 It is believed that 

 within perhaps one 

 hundred years, with the 

 aid of good laws and 



livino- it will 

 living, it Will 



A single cell scraped from the roof of the mouth 

 and highly magnified. The little dots are 

 bacteria, most of which are harmless. Notice 

 the comparative size of bacteria and cell. 



Deaths from tuberculosis compared with other 

 contagious diseases in the city of New York 



in 1908, 



be almost extinct. 



