﻿THE 
  BACTERIA 
  203 
  

  

  and, 
  upon 
  the 
  return 
  of 
  favorable 
  conditions, 
  may 
  grow 
  and 
  

   produce 
  the 
  kind 
  of 
  cell 
  which 
  formed 
  it. 
  Such 
  specially 
  pro- 
  

   duced 
  reproductive 
  cells 
  are 
  called 
  spores. 
  They 
  often 
  enable 
  

   the 
  bacteria 
  and 
  other 
  plants 
  to 
  live 
  through 
  periods 
  of 
  un- 
  

   favorable 
  conditions 
  -- 
  as 
  drought, 
  lack 
  of 
  proper 
  air, 
  absence 
  

   of 
  suitable 
  food, 
  and 
  unfavorable 
  temperature. 
  Some 
  kinds 
  

   can 
  withstand 
  freezing 
  or 
  boiling 
  temperatures. 
  It 
  is 
  much 
  

   more 
  difficult 
  to 
  destroy 
  the 
  spores 
  of 
  bacteria 
  than 
  the 
  vege- 
  

   tative, 
  or 
  growing, 
  cells. 
  There 
  are 
  very 
  few 
  spore-forming 
  

   bacteria 
  among 
  those 
  that 
  produce 
  diseases 
  of 
  men. 
  This 
  is 
  

   fortunate, 
  since 
  the 
  problem 
  of 
  combating 
  disease 
  would 
  be 
  

   much 
  more 
  complex 
  if 
  all 
  the 
  harmful 
  .bacteria 
  should 
  be 
  able 
  

   to 
  form 
  these 
  resistant 
  spores. 
  A 
  disease 
  known 
  as 
  anthrax 
  

   offers 
  a 
  good 
  illustration 
  of 
  the 
  way 
  in 
  which 
  spore 
  formation 
  

   may 
  increase 
  the 
  distribution 
  of 
  disease. 
  Anthrax 
  is 
  a 
  very 
  de- 
  

   structive 
  disease, 
  as 
  is 
  shown 
  by 
  the 
  fact 
  that, 
  prior 
  to 
  the 
  use 
  

   of 
  the 
  treatment 
  devised 
  by 
  Louis 
  Pasteur, 
  France 
  in 
  single 
  

   years 
  had 
  lost 
  as 
  much 
  as 
  120,000,000 
  worth 
  of 
  cattle 
  and 
  

   sheep. 
  The 
  disease 
  also 
  affects 
  men 
  and 
  may 
  cause 
  their 
  

   death, 
  as 
  it 
  does 
  that 
  of 
  cattle, 
  sheep, 
  and 
  other 
  animals, 
  in 
  

   from 
  a 
  few 
  hours 
  to 
  a 
  few 
  days 
  after 
  infection. 
  The 
  spores 
  of 
  

   anthrax 
  form 
  only 
  when 
  the 
  bacteria 
  are 
  exposed 
  to 
  the 
  air. 
  

   When 
  an 
  animal 
  dies 
  of 
  anthrax, 
  if 
  its 
  body 
  decays 
  while 
  ex- 
  

   posed 
  to 
  the 
  air, 
  millions 
  of 
  anthrax 
  spores 
  are 
  formed. 
  These 
  

   spores 
  can 
  lie 
  in 
  the 
  field 
  for 
  very 
  long 
  periods, 
  probably 
  

   several 
  seasons, 
  and 
  withstand 
  the 
  variations 
  in 
  temperature, 
  

   moisture, 
  and 
  light. 
  When 
  they 
  are 
  .introduced 
  into 
  the 
  ali- 
  

   mentary 
  tract 
  of 
  an 
  animal, 
  .they 
  soon 
  reach 
  the 
  circulatory 
  

   system, 
  where 
  they 
  grow 
  with 
  surprising 
  rapidity 
  and 
  may 
  

   soon 
  cause 
  the 
  death 
  of 
  the 
  newly 
  infected 
  animal. 
  The 
  de- 
  

   sirability 
  of 
  the 
  complete 
  destruction 
  of 
  bodies 
  of 
  animals 
  that 
  

   have 
  died 
  of 
  anthrax 
  is 
  evident. 
  

  

  190. 
  Bacterial 
  decay 
  and 
  its 
  significance. 
  The 
  bacteria 
  and 
  

   certain 
  other 
  dependent 
  organisms 
  (as 
  molds, 
  yeasts, 
  and 
  

   many 
  animals), 
  while 
  living 
  upon 
  the 
  bodies 
  or 
  the 
  products 
  of 
  

   plants 
  and 
  animals, 
  use 
  parts 
  of 
  them 
  as 
  food. 
  The 
  processes 
  

  

  