420 



GENERAL SCIENCE 



germs which not only cling to their legs but pass from 

 their x bodies in the discharges known as fly specks. Flies 

 ,^ are m ost effective spreaders 

 L v 1 of disease and must be kept 



screened away from sickness 

 and away from health. It 

 is estimated that a fly's life 

 is spent within the radius of 

 half a mile from its breed- 

 ing place. Consequently the 

 presence of flies indicates 

 that there must be, in the 

 immediate neighborhood, 

 filth in which they can 

 breed (Figure 371). 



Keep garbage cans cov- 

 ered and clean ; eliminate 

 manure piles and heaps of 

 kitchen waste ; carefully 

 screen every house. With 

 no place to breed and little to eat, flies will cease to be 

 a problem. 



Sewage Disposal and Public Health. We have learned 

 by very dear experience that our drinking water must 

 not be. polluted by sewage. The one water disease which 

 we most fear in the United States is typhoid fever, and 

 the only way in which a large supply of water may become 

 contaminated with typhoid germs is through sewage 

 wastes. 



In 1903 Cleveland had an epidemic of typhoid fever 

 as a result of contamination of the water supply by the 

 city's sewage. Many people bought spring water while 

 others took the precaution of boiling the city water. 



FIG. 371. The Foot of a Fly, 

 Magnified. 



