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  INTRODUCTION 
  TO 
  BOTANY 
  

  

  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 
  

  

  