﻿HISTORY 
  OF 
  THE 
  DISEASES 
  IN 
  THE 
  UNITED 
  STATES. 
  

  

  203 
  

  

  prepared 
  like 
  the 
  first 
  in 
  every 
  particular. 
  The 
  soil 
  in 
  the 
  box 
  was 
  kept 
  well 
  moist- 
  

   ened, 
  and 
  the 
  plants 
  remained 
  fresh. 
  This 
  experiment 
  was 
  made 
  on 
  August 
  2, 
  about 
  

   the 
  time 
  when 
  the 
  attack 
  outside 
  began 
  to 
  diminish 
  in 
  intensity. 
  The 
  following 
  are 
  

   the 
  results 
  of 
  examinations 
  on 
  the 
  dates 
  indicated, 
  the 
  original 
  experiments 
  being 
  

   numbered 
  by 
  capitals, 
  and 
  the 
  checks 
  by 
  small 
  letters, 
  thus 
  A, 
  a, 
  adult; 
  B, 
  b, 
  young 
  

   larvae; 
  C, 
  c, 
  older 
  larvae; 
  D, 
  d, 
  pupae: 
  

  

  On 
  the 
  same 
  day 
  this 
  experiment 
  was 
  begun 
  a 
  second 
  was 
  also 
  commenced, 
  like 
  

   the 
  first 
  in 
  every 
  particular 
  except 
  that 
  the 
  healthy 
  bugs 
  used 
  in 
  experimentation 
  

   were 
  exposed 
  to 
  fungus 
  individuals 
  for 
  only 
  five 
  hours, 
  and 
  then 
  placed 
  under 
  their 
  

   respective 
  glasses. 
  As 
  a 
  result, 
  on 
  August 
  15, 
  13 
  days 
  thereafter, 
  none 
  had 
  died, 
  thus 
  

   strongly 
  indicating 
  that 
  the 
  Entomophthora 
  did 
  not 
  exist 
  generally 
  in 
  the 
  fields, 
  and 
  

   that 
  it 
  could 
  not 
  be 
  communicated 
  during 
  a 
  period 
  of 
  five 
  hours' 
  exposure. 
  

  

  On 
  August 
  7 
  a 
  large 
  number 
  of 
  healthy 
  bugs 
  were 
  placed 
  under 
  glass 
  with 
  a 
  

   number 
  which 
  had 
  recently 
  died 
  from 
  Entomophthora, 
  the 
  moisture 
  in 
  the 
  vessel 
  

   being 
  absorbed 
  by 
  calcium 
  chloride. 
  A 
  check 
  experiment 
  was 
  also 
  commenced, 
  

   where 
  the 
  material 
  and 
  the 
  conditions 
  were 
  the 
  same, 
  except 
  the 
  humidity 
  of 
  the 
  

   atmosphere, 
  care 
  being 
  taken 
  to 
  have 
  the 
  latter 
  as 
  nearly 
  saturated 
  with 
  moisture 
  as 
  

   possible. 
  August 
  10 
  the 
  original 
  experiment 
  was 
  divided, 
  and 
  a 
  portion 
  of 
  the 
  

   healthy 
  bugs 
  removed 
  and 
  placed 
  in 
  a 
  damp 
  environment, 
  the 
  remainder 
  being 
  kept 
  

   under 
  the 
  original 
  dry 
  conditions. 
  The 
  results 
  on 
  August 
  22 
  were 
  as 
  follows: 
  In 
  

   the 
  original 
  experiment, 
  where 
  the 
  healthy 
  bugs 
  had 
  been 
  continually 
  in 
  dry 
  quar- 
  

   ters, 
  not 
  a 
  single 
  bug 
  had 
  died 
  from 
  Entomophthora. 
  Not 
  only 
  this, 
  but 
  none 
  of 
  

   those 
  which 
  had 
  been 
  removed 
  after 
  three 
  days 
  and 
  placed 
  in 
  dry 
  quarters 
  had 
  died, 
  

   showing 
  that 
  the 
  disease 
  was 
  not 
  contracted 
  and 
  did 
  not 
  develop 
  in 
  healthy 
  bugs, 
  

   though 
  kept 
  exposed 
  in 
  a 
  dry 
  atmosphere 
  for 
  15 
  days; 
  nor 
  could 
  it 
  be 
  originated 
  by 
  

   placing 
  in 
  a 
  damp 
  atmosphere 
  for 
  12 
  days 
  bugs 
  which 
  had 
  been 
  exposed 
  to 
  conta- 
  

   gion 
  for 
  three 
  days 
  in 
  dry 
  quarters. 
  The 
  results 
  with 
  the 
  check 
  experiment 
  were 
  

   quite 
  different. 
  Within 
  five 
  days 
  after 
  being 
  confined 
  with 
  the 
  Entomophthora 
  the 
  

   healthy 
  bugs 
  began 
  to 
  die 
  from 
  the 
  effects 
  of 
  the 
  disease, 
  and 
  in 
  three 
  days 
  more 
  

   every 
  one 
  had 
  died 
  from 
  the 
  same 
  cause, 
  their 
  bodies 
  being 
  covered 
  with 
  spores. 
  

  

  Still 
  another 
  experiment 
  was 
  tried, 
  which 
  consisted 
  in 
  confining 
  a 
  large 
  number 
  

   of 
  healthy 
  bugs 
  with 
  others 
  diseased 
  in 
  a 
  damp 
  environment, 
  and 
  when 
  the 
  fungus 
  

   had 
  destroyed 
  a 
  portion, 
  the 
  remainder 
  were 
  divided 
  and 
  a 
  part 
  removed 
  to 
  dry 
  

   quarters. 
  The 
  result 
  was, 
  that 
  while 
  those 
  left 
  in 
  damp 
  confinement 
  continued 
  to 
  

   die, 
  none 
  of 
  those 
  inclosed 
  in 
  dry 
  environment 
  were 
  destroyed. 
  As 
  the 
  fungus 
  had 
  

   by 
  this 
  time 
  become 
  distributed 
  over 
  the 
  experiment 
  farm, 
  so 
  that 
  I 
  could 
  tell 
  with 
  

   certainty 
  whether 
  material 
  from 
  fields 
  was 
  in 
  a 
  perfectly 
  healthy 
  condition 
  or 
  not, 
  no 
  

   further 
  experiments 
  were 
  made 
  in 
  this 
  direction. 
  

  

  From 
  the 
  foregoing, 
  it 
  will 
  be 
  observed 
  that 
  the 
  essential 
  element 
  in 
  all 
  of 
  these 
  

   experiments 
  was 
  an 
  abundance 
  of 
  moisture, 
  without 
  which 
  the 
  Entomophthora 
  could 
  

   neither 
  become 
  established 
  nor 
  flourish 
  after 
  it 
  had 
  gained 
  a 
  footing. 
  Again, 
  the 
  

   extent 
  to 
  which 
  the 
  disease 
  will 
  prove 
  contagious 
  will 
  depend 
  upon 
  the 
  number 
  of 
  

   bugs. 
  Without 
  great 
  numbers 
  massed 
  together 
  comparatively 
  few 
  would 
  contract 
  

   the 
  disease. 
  To 
  sum 
  up 
  the 
  matter, 
  there 
  is 
  little 
  hope 
  for 
  relief 
  to 
  the 
  farmer 
  from 
  

   the 
  influence 
  of 
  Entomophthora, 
  except 
  when 
  the 
  chinch-bugs 
  are 
  abundant 
  and 
  

   massed 
  together 
  in 
  great 
  numbers, 
  and 
  during 
  a 
  period 
  of 
  wet 
  weather. 
  I 
  have 
  sue- 
  

  

  