﻿1890.] 
  BOTANICAL 
  GAZETTE. 
  9 
  

  

  large 
  dew 
  drops 
  may 
  be 
  found 
  upon 
  the 
  lily 
  leaves. 
  A 
  

   little 
  cool 
  weather, 
  or 
  a 
  few 
  warm, 
  dry 
  days 
  free 
  from 
  dew, 
  

   will 
  check 
  the 
  activity' 
  of 
  the 
  disease, 
  while 
  a 
  warm, 
  damp 
  

   day 
  will 
  cause 
  it 
  to 
  spread 
  with 
  great 
  rapidity. 
  The 
  disease 
  

   first 
  appears 
  as 
  a 
  minute 
  orange-colored 
  spot 
  upon 
  a 
  leaf 
  or 
  

   flower, 
  usually 
  on 
  the 
  upper 
  side 
  of 
  the 
  leaf. 
  Fig. 
  i 
  (a) 
  

   shows 
  an 
  early 
  stage. 
  The 
  spot 
  gradually 
  increases 
  in 
  size, 
  

   and 
  finally 
  spreads 
  throughout 
  the 
  whole 
  leaf. 
  In 
  this 
  way 
  

   whole 
  plants 
  maybe 
  killed, 
  and 
  onlv 
  the 
  stalks 
  left 
  standing. 
  

   It 
  is 
  not 
  unusual 
  to 
  find 
  several 
  of 
  these 
  spots 
  on 
  the 
  same 
  

   leaf, 
  as 
  in 
  fig. 
  i. 
  If, 
  for 
  an}- 
  reason, 
  the 
  progress 
  of 
  the 
  

   disease 
  is 
  checked, 
  these 
  become 
  dry, 
  leathery 
  patches 
  of 
  a 
  

   bufi:' 
  color. 
  

  

  It 
  was 
  thought 
  possible, 
  by 
  some 
  of 
  those 
  who 
  had 
  seen 
  

   the 
  diseased 
  specimens, 
  that 
  the 
  spots 
  might 
  be 
  due 
  to 
  the 
  

   stings 
  of 
  insects. 
  Though 
  at 
  first 
  this 
  did 
  not 
  seem 
  unlikely, 
  

   a 
  closer 
  acquaintance 
  with 
  the 
  disease 
  rendered 
  it 
  highly 
  im- 
  

   probable. 
  

  

  Sections 
  of 
  the 
  spots 
  examined 
  under 
  the 
  microscope 
  re- 
  

   vealed 
  nothing 
  more 
  than 
  that 
  in 
  the 
  diseased 
  area 
  the 
  struc- 
  

   ture 
  of 
  the 
  leaf 
  had 
  collapsed 
  ; 
  while 
  along 
  the 
  edges 
  of 
  the 
  

   spot 
  the 
  cells 
  were 
  somewhat 
  swollen 
  and 
  the 
  cell 
  walls 
  

   thickened. 
  The 
  cell 
  contents 
  were 
  slightly 
  shrunken, 
  and 
  

   contained 
  a 
  number 
  of 
  bright 
  dots 
  which 
  did 
  not 
  stain 
  with 
  

   the 
  ordinary 
  reagents. 
  In 
  a 
  few 
  cases 
  where 
  specimens 
  

   were 
  teased 
  an 
  occasional 
  hypha 
  of 
  a 
  fungus 
  was 
  found, 
  

   which, 
  however, 
  might 
  easily 
  have 
  come 
  from 
  external 
  con- 
  

   tamination. 
  In 
  a 
  slightly 
  more 
  advanced 
  stage 
  of 
  the 
  dis- 
  

   ease 
  hypha^ 
  of 
  a 
  fungus 
  might 
  be 
  found 
  ramifying 
  through 
  

   the 
  soft 
  decaying 
  tissues, 
  the 
  gonidiophores 
  appearing 
  on 
  

   the 
  surface 
  (fig. 
  2). 
  

  

  This 
  fungus 
  invariabl}' 
  appears 
  in 
  advanced 
  stages 
  of 
  the 
  

   disease 
  ; 
  moreover, 
  it 
  is 
  always 
  the 
  first 
  to 
  appear. 
  Other 
  

   fungi, 
  such 
  as 
  Macrosporium, 
  Eurotium, 
  and 
  Penicillium, 
  

   also 
  appear 
  on 
  the 
  decaying 
  leaves, 
  but 
  thit, 
  fungus 
  invaria- 
  

   bly 
  precedes 
  all 
  others. 
  At 
  the 
  same 
  time, 
  as 
  it 
  could 
  never 
  

   be 
  found 
  until 
  the 
  tissue 
  had 
  become 
  pretty 
  thoroughly 
  rot- 
  

   ten, 
  it 
  .seemed 
  at 
  first 
  sight 
  to 
  be 
  rather 
  a 
  consequence 
  than 
  

   a 
  cause 
  of 
  the 
  disease. 
  

  

  Early 
  in 
  April 
  I 
  was 
  obliged 
  to 
  return 
  to 
  the 
  United 
  

   States, 
  and 
  for 
  a 
  time 
  my 
  investigations 
  were 
  interrupted 
  to 
  

   be 
  resumed 
  again 
  in 
  the 
  summer, 
  when 
  I 
  had 
  specimens 
  for- 
  

   warded 
  to 
  me 
  from 
  Bermuda, 
  It 
  had 
  seemed 
  possible 
  that 
  

   the 
  disease 
  might 
  be 
  due 
  to 
  bacteria, 
  on 
  account 
  of 
  its 
  pecul- 
  

  

  