216 INTRODUCTION TO BOTANY 
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Fig. 171. A chart illustrating the number of deaths from typhoid fever 
before, during, and after the introduction of improved systems of sewage 
disposal and water supply 
Five prominent cities of the world are selected. The figures indicate the num- 
ber of deaths for each 10,000 inhabitants. Rearranged from a chart in Abbott’s 
“Hygiene of Transmissible Diseases” 
The house fly is a dangerous agent of distribution of typhoid 
and: probably of other disease bacteria. The atmosphere is an 
efficient carrier of the bacteria of tuberculosis. Every possible 
effort should be made to remove the breeding places of flies 
