﻿HISTORY 
  OF 
  THE 
  DISEASES 
  IN 
  THE 
  UNITED 
  STATES. 
  195 
  

  

  servations 
  upon 
  the 
  fluids 
  of 
  the 
  bodies 
  of 
  chinch-bugs, 
  which 
  resulted 
  in 
  his 
  

   discovery 
  of 
  a 
  bacterial 
  form, 
  undoubtedly 
  the 
  causal 
  agency 
  in 
  the 
  produc- 
  

   tion 
  of 
  one 
  of 
  the 
  epidemic 
  diseases 
  of 
  the 
  chinch-bug. 
  From 
  this 
  date 
  more 
  

   or 
  less 
  attention 
  has 
  been 
  constantly 
  given 
  to 
  the 
  investigation 
  of 
  these 
  dis- 
  

   eases. 
  The 
  account 
  of 
  Professor 
  Forbes's 
  observations 
  and 
  experiments 
  lead- 
  

   ing 
  to 
  the 
  discovery 
  of 
  the 
  deadly 
  Micrococcus 
  would 
  make 
  a 
  most 
  interesting 
  

   chapter 
  of 
  this 
  report, 
  if 
  space 
  permitted 
  its 
  insertion. 
  The 
  observations 
  

   were 
  made 
  with 
  characteristic 
  care 
  and 
  accuracy. 
  They 
  were 
  presented 
  in 
  

   the 
  twelfth 
  report 
  (1882) 
  of 
  the 
  State 
  Entomologist 
  on 
  the 
  noxious 
  and 
  ben- 
  

   eficial 
  insects 
  of 
  the 
  State 
  of 
  Illinois, 
  the 
  report 
  not 
  being 
  printed 
  until 
  1883. 
  

   Professor 
  Forbes 
  says 
  : 
  

  

  My 
  own 
  observations 
  upon 
  this 
  interesting 
  subject 
  [epidemic 
  disease 
  among 
  

   chinch-bugs] 
  began 
  on 
  the 
  3d 
  of 
  August, 
  1882, 
  at 
  which 
  time 
  I 
  commenced 
  an 
  ex- 
  

   amination 
  of 
  the 
  fluids 
  of 
  the 
  bodies 
  of 
  specimens 
  [of 
  chinch-bugs] 
  of 
  various 
  ages 
  

   and 
  from 
  various 
  situations, 
  with 
  a 
  view 
  to 
  familiarizing 
  myself 
  with 
  their 
  appear- 
  

   ance 
  in 
  the 
  normal 
  condition 
  of 
  the 
  insect, 
  in 
  order 
  that 
  I 
  might 
  be 
  able 
  afterwards 
  

   readily 
  to 
  detect 
  any 
  departure 
  from 
  that 
  condition 
  which 
  circumstances 
  should 
  de- 
  

   velop. 
  On 
  the 
  5th 
  of 
  August, 
  on 
  crushing 
  some 
  chinch-bugs 
  under 
  a 
  cover 
  upon 
  a 
  

   microscope 
  slide, 
  and 
  diluting 
  the 
  fluids 
  with 
  freshly 
  distilled 
  water, 
  I 
  found 
  them 
  

   often 
  swarming 
  with 
  minute 
  rod-like 
  bodies, 
  which 
  I 
  took 
  to 
  be 
  bacteria, 
  sometimes 
  

   forming 
  small 
  adherent 
  masses. 
  Careful 
  examination 
  under 
  a 
  power 
  of 
  1,000 
  di- 
  

   ameters 
  showed 
  that 
  these 
  rods 
  were 
  usually 
  formed 
  of 
  two 
  and 
  sometimes 
  four 
  

   oval 
  particles, 
  joined 
  end 
  to 
  end. 
  Hundreds 
  would 
  often 
  cross 
  the 
  field 
  of 
  view 
  in 
  

   a 
  minute. 
  In 
  order 
  to 
  determine 
  whether 
  these 
  bacteria 
  occurred 
  in 
  the 
  circulating 
  

   fluid 
  or 
  in 
  some 
  other 
  part 
  of 
  the 
  body, 
  I 
  cut 
  off 
  the 
  legs 
  and 
  head 
  of 
  a 
  specimen 
  in 
  

   a 
  small 
  quantity 
  of 
  distilled 
  water 
  upon 
  a 
  slide, 
  allowing 
  the 
  blood 
  to 
  escape. 
  The 
  

   quantity 
  of 
  the 
  fluid 
  was, 
  however, 
  highly 
  diluted, 
  and 
  I 
  could 
  find 
  but 
  two 
  bacteria. 
  

   Crushing 
  the 
  remainder 
  of 
  the 
  body 
  of 
  this 
  specimen 
  as 
  usual, 
  bacteria 
  were 
  pres- 
  

   ent 
  but 
  not 
  abundant. 
  On 
  the 
  7th 
  of 
  August, 
  I 
  repeated 
  this 
  observation 
  several 
  

   times, 
  with 
  results 
  identical, 
  in 
  every 
  particular, 
  with 
  those 
  just 
  detailed, 
  except 
  that 
  

   the 
  bacteria 
  were 
  much 
  more 
  abundant 
  in 
  some 
  of 
  the 
  insects 
  than 
  in 
  others. 
  Ap- 
  

   preciating 
  the 
  possibility 
  of 
  the 
  infection 
  of 
  the 
  fluids 
  examined 
  from 
  outside 
  

   ' 
  sources, 
  I 
  used 
  every 
  precaution 
  to 
  disinfect 
  all 
  tools 
  and 
  materials 
  with 
  which 
  

   I 
  worked. 
  The 
  water 
  with 
  which 
  the 
  fluids 
  of 
  the 
  chinch-bug 
  were 
  diluted 
  had 
  

   been 
  freshly 
  distilled 
  and 
  re-distilled, 
  and 
  the 
  forceps, 
  knives, 
  needles, 
  .slides 
  and 
  

   cover-glasses 
  were 
  all 
  passed 
  through 
  the 
  flame 
  of 
  an 
  alcohol 
  lamp 
  just 
  before 
  being 
  

   used. 
  In 
  order 
  to 
  assure 
  myself 
  that 
  the 
  bacteria 
  observed 
  came 
  actually 
  from 
  the 
  

   interior 
  of 
  the 
  bugs, 
  I 
  carefully 
  washed 
  several 
  examples 
  with 
  a 
  camel's 
  hair 
  brush 
  

   in 
  a 
  drop 
  of 
  water 
  upon 
  the 
  slide, 
  but 
  could 
  find 
  no 
  bacteria 
  in 
  the 
  fluid 
  used. 
  By 
  

   crushing 
  the 
  same 
  specimens 
  and 
  treating 
  them 
  as 
  before, 
  the 
  bacteria 
  appeared 
  in 
  the 
  

   usual 
  numbers. 
  It 
  then 
  occurred 
  to 
  me 
  that 
  it 
  was 
  possible 
  that 
  the 
  corn 
  itself, 
  upon 
  

   which 
  these 
  bugs 
  were 
  feeding, 
  was 
  in 
  a 
  diseased 
  condition, 
  and 
  that 
  the 
  bacteria 
  were 
  

   derived 
  from 
  its 
  juices. 
  I 
  consequently 
  took 
  portions 
  of 
  the 
  pith 
  of 
  several 
  stalks, 
  

   crushed 
  them 
  upon 
  the 
  slide, 
  and 
  examined 
  the 
  sap 
  with 
  high 
  powers 
  of 
  the 
  micro- 
  

   scope. 
  I 
  found, 
  of 
  course, 
  a 
  multitude 
  of 
  minute 
  particles 
  of 
  various 
  kinds 
  and 
  va- 
  

   riously 
  aggregated. 
  Most 
  of 
  them 
  were 
  agitated 
  by 
  the 
  Brownian 
  movement, 
  but 
  

   none 
  of 
  them 
  were 
  recognizable 
  as 
  bacteria. 
  These 
  observations 
  were 
  several 
  times 
  

   repeated, 
  and 
  I 
  finally 
  stained 
  and 
  mounted 
  some 
  of 
  the'solid 
  particles 
  from 
  the 
  sap, 
  

   for 
  more 
  careful 
  study 
  under 
  high 
  powers. 
  On 
  the 
  9th 
  of 
  August, 
  I 
  made 
  a 
  visit 
  to 
  

  

  