PLANTS WITHOUT CHLOROPHYLL 



153 



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. 



openings, or through a 

 break in the skin. They 

 maybe 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 



Deaths from tuberculosis compared with other cQnifQrv livinff it will 

 contagious diseases in the city of New York ^ ^^' 



in 1908. be almost extinct. 



