﻿212 
  CONTAGIOUS 
  DISEASES 
  OF 
  THE 
  CHINCH-BUG. 
  

  

  fungus 
  covering 
  all 
  the 
  exposed 
  surface. 
  June 
  19, 
  surface 
  slightly 
  tinged 
  with 
  yel- 
  

   low, 
  indicating 
  ripening 
  of 
  spores. 
  June 
  22, 
  masses 
  of 
  spores 
  may 
  be 
  detached 
  by 
  

   vigorous 
  shaking. 
  June 
  24, 
  spores 
  readily 
  detached; 
  surface 
  decidedly 
  brownish. 
  

  

  June 
  12, 
  materials 
  prepared 
  as 
  above. 
  From 
  a 
  lot 
  of 
  chinch-bugs 
  obtained 
  in 
  

   the 
  field 
  June 
  2, 
  in 
  which 
  the 
  Sporotrichum 
  had 
  appeared 
  spontaneously, 
  a 
  dead 
  

   specimen 
  was 
  taken 
  June 
  12, 
  3 
  p. 
  m., 
  and 
  dropped 
  into 
  the 
  tube 
  on 
  the 
  surface 
  of 
  the 
  

   meal. 
  June 
  14, 
  growth 
  beginning. 
  June 
  15, 
  fungus 
  growing 
  freely 
  all 
  along 
  the 
  

   track 
  touched 
  by 
  the 
  chinch-bug. 
  June 
  17, 
  surface 
  of 
  the 
  meal 
  well 
  covered 
  with 
  

   the 
  growth; 
  blue 
  mould 
  appearing 
  at 
  the 
  bottom 
  of 
  the 
  tube. 
  June 
  18, 
  Sporotri- 
  

   chum 
  as 
  before; 
  blue 
  mould 
  spreading. 
  June 
  20, 
  spore 
  clusters 
  of 
  Sporotrichum 
  

   showing 
  quite 
  distinctly. 
  June 
  22, 
  spores 
  quite 
  yellowish 
  and 
  loosened 
  by 
  jarring. 
  

   June 
  27, 
  a 
  peculiar 
  pink 
  color 
  apparent 
  along 
  the 
  margins 
  of 
  the 
  mould, 
  pene- 
  

   trating 
  deeply 
  into 
  the 
  meal. 
  On 
  examination, 
  this 
  color 
  proved 
  to 
  be 
  due 
  to 
  a 
  

   bacterial 
  species 
  which 
  was 
  transferred 
  to 
  an 
  agar 
  tube 
  for 
  separate 
  cultivation. 
  

  

  Numerous 
  attempts 
  were 
  made, 
  beginning 
  June 
  15, 
  for 
  the 
  artificial 
  culture 
  of 
  

   the 
  Sporotrichum 
  in 
  the 
  open 
  air, 
  without 
  resort 
  to 
  the 
  sterilization 
  methods 
  of 
  the 
  

   experiments 
  given 
  above, 
  but 
  all 
  were 
  unsuccessful. 
  The 
  materials 
  used 
  were 
  corn 
  

   meal 
  saturated 
  with 
  beef 
  broth; 
  the 
  same 
  acidulated 
  with 
  acetic 
  or 
  tartaric 
  acid, 
  for 
  

   the 
  purpose 
  of 
  retarding 
  the 
  development 
  of 
  bacteria; 
  corn 
  meal 
  soaked 
  with 
  a 
  

   modified 
  form 
  of 
  Cohn's 
  solution, 
  acidulated 
  as 
  before; 
  corn 
  meal 
  mixed 
  with 
  water; 
  

   corn 
  meal 
  soaked 
  with 
  an 
  extract 
  of 
  the 
  excrement 
  of 
  horses, 
  variously 
  acidulated 
  

   with 
  tartaric 
  acid; 
  the 
  solid 
  excrement 
  itself; 
  the 
  thick 
  scum 
  from 
  beef 
  broth; 
  and 
  

   raw 
  beef 
  alone. 
  

  

  Infection 
  experiments 
  were 
  made 
  with 
  chinch-bugs, 
  Cecropia 
  moths, 
  the 
  grain 
  

   aphis 
  and 
  other 
  plant 
  lice, 
  and 
  with 
  saw-fly 
  larvae 
  (from 
  grass). 
  

  

  The 
  first 
  chinch-bug 
  experiment 
  was 
  begun 
  May 
  11, 
  1891, 
  with 
  only 
  about 
  50 
  speci- 
  

   mens 
  placed 
  under 
  a 
  bell 
  glass 
  with 
  fresh 
  wheat, 
  and 
  exposed 
  to 
  infection 
  from 
  several 
  

   dead 
  beetles 
  (Disonycha 
  pennsylvanica) 
  covered 
  with 
  fungus 
  spores 
  from 
  a 
  lot 
  of 
  

   that 
  species 
  which 
  had 
  largely 
  perished 
  with 
  this 
  fungus 
  attack. 
  Three 
  days 
  later 
  

   one 
  chinch-bug 
  was 
  dead, 
  and 
  in 
  five 
  days 
  another 
  also. 
  May 
  19 
  two 
  more, 
  covered 
  

   with 
  Sporotrichum, 
  were 
  taken 
  from 
  the 
  glass. 
  May 
  20, 
  at 
  8 
  A. 
  m., 
  another, 
  which 
  

   had 
  certainly 
  been 
  alive 
  at 
  2 
  p. 
  m. 
  of 
  the 
  preceding 
  day, 
  was 
  removed, 
  whitened 
  with 
  

   the 
  mycelium 
  of 
  the 
  fungus. 
  On 
  the 
  22d 
  of 
  May 
  two 
  more 
  had 
  died 
  from 
  the 
  fungus 
  

   attack, 
  and 
  on 
  the 
  23d 
  another. 
  By 
  the 
  29th 
  of 
  the 
  month, 
  18 
  days 
  after 
  the 
  experi- 
  

   ment 
  began, 
  all 
  but 
  one 
  of 
  the 
  chinch-bugs 
  were 
  dead 
  and 
  covered 
  with 
  the 
  Sporo- 
  

   trichum, 
  and 
  this 
  one 
  died 
  shortly 
  after. 
  Other 
  specimens 
  of 
  the 
  same 
  lot, 
  kept 
  in 
  

   similar 
  conditions 
  as 
  a 
  check, 
  had 
  in 
  the 
  meantime 
  continued 
  without 
  loss. 
  

  

  Next, 
  May 
  29, 
  30 
  insects 
  were 
  placed, 
  with 
  a 
  wheat 
  plant 
  for 
  food, 
  in 
  a 
  breed- 
  

   ing 
  cage, 
  and 
  two 
  dead 
  specimens 
  whitened 
  with 
  the 
  fungus 
  growth 
  were 
  placed 
  

   among 
  them. 
  Twenty-four 
  hours 
  later 
  these 
  dead 
  insects 
  were 
  removed. 
  On 
  the 
  

   3d 
  day 
  of 
  June, 
  five 
  days 
  from 
  the 
  beginning 
  of 
  the 
  experiment, 
  one 
  insect 
  was 
  

   dead 
  with 
  the 
  fungus 
  affection, 
  and 
  on 
  the 
  seventh 
  two 
  more. 
  Three 
  days 
  later 
  

   two 
  additional 
  specimens 
  were 
  removed 
  from 
  the 
  cage 
  whitened 
  with 
  an 
  abundant 
  

   growth 
  of 
  Sporotrichum, 
  and 
  the 
  remainder 
  of 
  the 
  chinch-bugs 
  in 
  this 
  lot 
  were 
  then 
  

   converted 
  to 
  another 
  use. 
  None 
  had 
  died 
  in 
  the 
  meantime' 
  in 
  the 
  check 
  lot. 
  

  

  June 
  1 
  a 
  similar 
  experiment 
  was 
  begun 
  with 
  30 
  chinch-bugs, 
  among 
  which 
  four 
  

   infected 
  ones 
  were 
  introduced 
  and 
  left 
  two 
  days. 
  By 
  June 
  10, 
  three 
  had 
  died 
  with 
  

   the 
  fungus 
  attack, 
  and 
  the 
  remainder 
  were 
  then 
  otherwise 
  used, 
  the 
  check 
  lot 
  having 
  

   in 
  the 
  meantime 
  remained 
  without 
  loss. 
  

  

  June 
  5, 
  30 
  chinch-bugs 
  were 
  dusted 
  with 
  spores 
  from 
  an 
  agar 
  culture 
  of 
  Sporo- 
  

   richum, 
  and 
  two 
  days 
  later 
  two 
  of 
  these 
  were 
  dead. 
  June 
  9 
  two 
  others 
  had 
  died, 
  

   and 
  by 
  the 
  11th 
  nine 
  of 
  the 
  30 
  had 
  perished, 
  with 
  a 
  rapid 
  subsequent 
  development 
  

  

  