﻿93 
  

  

  my 
  office, 
  gave 
  an 
  opportunity 
  not 
  previously 
  possible 
  for 
  careful 
  ex- 
  

   perimental 
  field 
  work 
  with 
  the 
  fungi 
  of 
  contagious 
  diseases 
  and 
  regu- 
  

   lar 
  observations 
  of 
  the 
  results. 
  Four 
  such 
  experiments 
  were 
  conse- 
  

   quently 
  made, 
  the 
  first 
  beginning 
  May 
  14, 
  the 
  second, 
  May 
  23, 
  the 
  

   third, 
  September 
  4, 
  and 
  the 
  fourth, 
  September 
  20. 
  

  

  The 
  material 
  for 
  infection 
  was 
  obtained 
  from 
  cultures 
  and 
  infec- 
  

   tion 
  experiments 
  in 
  progress 
  at 
  my 
  office, 
  and 
  from 
  various 
  outside 
  

   sources 
  indicated 
  in 
  the 
  detailed 
  descriptions. 
  As 
  these 
  are 
  the 
  only 
  

   experiments 
  of 
  the 
  kind 
  which 
  it 
  has 
  been 
  possible 
  for 
  us 
  to 
  follow 
  

   with 
  practical 
  continuity, 
  they 
  seem 
  worth 
  reporting 
  in 
  some 
  detail. 
  

  

  May 
  14, 
  in 
  a 
  plot 
  of 
  winter 
  wheat 
  containing 
  about 
  eight 
  acres 
  

   moderately 
  infested 
  with 
  adult 
  chinch-bugs 
  and 
  young 
  just 
  begin- 
  

   ning 
  to 
  hatch, 
  about 
  one 
  hundred 
  and 
  twenty-five 
  dead 
  chinch-bugs, 
  

   covered 
  with 
  a 
  good 
  growth 
  of 
  Sporotrichum 
  glohulifermn, 
  and 
  a 
  

   corn-meal 
  culture 
  of 
  the 
  same 
  fungus 
  having 
  a 
  surface 
  of 
  about 
  a 
  

   square 
  inch, 
  were 
  placed 
  in 
  stools 
  of 
  wheat 
  in 
  a 
  selected 
  part 
  of 
  the 
  

   field, 
  the 
  locality 
  being 
  marked 
  for 
  observation. 
  The 
  ground 
  was 
  

   somewhat 
  damp 
  at 
  the 
  time, 
  a 
  sprinkle 
  of 
  rain 
  (.1 
  inch) 
  having 
  fallen 
  

   the 
  night 
  before, 
  and 
  1.5 
  inches 
  on 
  the 
  night 
  of 
  the 
  11th. 
  The 
  wheat 
  

   was 
  trampled 
  down 
  in 
  several 
  places 
  where 
  the 
  infested 
  material 
  was 
  

   distributed 
  in 
  order 
  to 
  shelter 
  the 
  ground 
  and 
  keep 
  it 
  moist. 
  A 
  quar- 
  

   ter 
  of 
  an 
  inch 
  of 
  rain 
  fell 
  on 
  the 
  evening 
  of 
  the 
  15th, 
  and 
  .13 
  of 
  an 
  

   inch 
  on 
  the 
  evening 
  of 
  the 
  18th, 
  followed 
  by 
  a 
  sprinkle 
  merely 
  on 
  the 
  

   night 
  of 
  the 
  I9th. 
  The 
  weather 
  of 
  this 
  interval 
  was 
  cloudy 
  more 
  

   than 
  half 
  the 
  time. 
  The 
  mean 
  daily 
  temperature 
  ranged 
  from 
  41° 
  to 
  

   61° 
  Fahr. 
  between 
  the 
  14th, 
  when 
  the 
  experiment 
  began, 
  and 
  the 
  22d, 
  

   when 
  the 
  first 
  examination 
  of 
  the 
  situation 
  was 
  made. 
  The 
  minimum 
  

   reading 
  reached 
  the 
  freezing 
  point 
  but 
  once 
  (on 
  May 
  21) 
  and 
  the 
  

   highest 
  temperature 
  of 
  the 
  interval 
  was 
  75°. 
  

  

  On 
  the 
  22d 
  the 
  ground 
  was 
  slightly 
  damp 
  and 
  chinch-bugs 
  were 
  

   rather 
  numerous, 
  many 
  of 
  the 
  eggs 
  showing 
  considerable 
  develop- 
  

   ment. 
  No 
  traces 
  of 
  fresh 
  fungous 
  growth 
  were 
  found! 
  A 
  large 
  quan- 
  

   tity 
  of 
  miscellaneous 
  material 
  from 
  two 
  contagion 
  boxes 
  in 
  the 
  labora- 
  

   tory 
  and 
  from 
  artificial 
  cultures 
  on 
  corn 
  meal 
  were 
  distributed 
  this 
  

   day 
  in 
  the 
  same 
  field, 
  together 
  with 
  a 
  small 
  number 
  of 
  chinch-bugs 
  

   covered 
  with 
  a 
  fresh 
  fungous 
  growth. 
  Upon 
  the 
  ground 
  where 
  these 
  

   distributions 
  were 
  made 
  straw 
  and 
  grass 
  were 
  scattered 
  to 
  preserve 
  

   the 
  surface 
  moisture. 
  

  

  An 
  examination 
  of 
  the 
  field 
  was 
  made 
  May 
  27, 
  the 
  interval 
  having 
  

   been 
  clear 
  and 
  dry 
  except 
  for 
  a 
  slight 
  sprinkle 
  of 
  rain 
  on 
  the 
  night 
  

   of 
  the 
  2Hth, 
  and 
  the 
  ground 
  was 
  consequently 
  very 
  dry. 
  No 
  fresh 
  

   fungous 
  growth 
  was 
  discoverable, 
  and 
  the 
  contents 
  of 
  two 
  more 
  ciilture 
  

   pans, 
  each 
  a 
  foot 
  in 
  diameter, 
  together 
  with 
  a 
  fruit- 
  jar 
  culture 
  of 
  

   Sporotrichum 
  and 
  a 
  miscellaneous 
  lot 
  of 
  chinch-bugs 
  covered 
  with 
  

   the 
  same 
  muscardine 
  fungus 
  as 
  that 
  received 
  from 
  correspondents, 
  were 
  

   also 
  scattered 
  in 
  the 
  field. 
  Chinch-bugs 
  were 
  pairing 
  and 
  young 
  

   were 
  hatching 
  in 
  some 
  numbers. 
  On 
  the 
  last 
  of 
  this 
  month, 
  no 
  notice- 
  

   able 
  rain 
  having 
  occurred 
  since 
  the 
  18th, 
  another 
  thorough 
  examina- 
  

   tion 
  of 
  the 
  field 
  was 
  made. 
  No 
  traces 
  of 
  fresh 
  fungous 
  growth 
  were 
  

   seen 
  on 
  the 
  dry 
  material, 
  which 
  could 
  still 
  be 
  found 
  on 
  the 
  surface. 
  

  

  