﻿1890.] 
  BOTANIC 
  AI. 
  GAZETTE. 
  1 
  73 
  

  

  result 
  was 
  the 
  same 
  as 
  that 
  obtained 
  in 
  the 
  previous 
  experi- 
  

   ments. 
  Some 
  efforts 
  were 
  made 
  at 
  obtaininfj 
  the 
  ferment 
  in 
  

   a 
  pure 
  state 
  with 
  a 
  measure 
  of 
  success. 
  Marshall-Ward 
  

   found 
  that 
  alcohol 
  coagulated 
  the 
  ferment. 
  I 
  found 
  that 
  

   on 
  adding 
  20 
  cc. 
  of 
  90 
  per 
  cent, 
  alcohol 
  to 
  10 
  cc 
  of 
  the 
  filtered 
  

   liquid 
  obtained 
  as 
  in 
  the 
  former 
  experiments, 
  a 
  heavy 
  

   gray 
  flocciilent 
  precipitate 
  was 
  formed. 
  This 
  was 
  fil- 
  

   tered 
  oil 
  and 
  the 
  filtrate 
  was 
  evaporated 
  at 
  a 
  low 
  tempera- 
  

   ture. 
  Its 
  residue 
  was 
  then 
  redissolved 
  in 
  water. 
  Pieces 
  of 
  

   vegetable 
  tissue 
  put 
  into 
  this 
  liquid 
  underwent 
  no 
  change, 
  so 
  

   that 
  it 
  was 
  evident 
  that 
  the 
  precipitate 
  contained 
  the 
  

   effective 
  substance. 
  The 
  precipitate 
  is 
  readily 
  soluble 
  

   m 
  water, 
  and 
  the 
  solution 
  thus 
  made 
  acts 
  in 
  the 
  same 
  way 
  on 
  

   plant 
  tissue 
  as 
  the 
  original 
  liquid. 
  x\ll 
  attempts 
  at 
  obtaining 
  

   the 
  ferment 
  in 
  a 
  purer 
  state 
  have 
  failed. 
  It 
  is 
  a 
  neutral 
  sub- 
  

   stance, 
  its 
  efficiency 
  is 
  destroyed 
  by 
  heat, 
  and 
  seen 
  under 
  

   the 
  microscope 
  it 
  is 
  amorphous, 
  never 
  so 
  far 
  as 
  I 
  have 
  seen 
  

   assuming 
  a 
  crystalline 
  form. 
  Not 
  only 
  was 
  this 
  precipitate 
  

   obtained 
  directly 
  from 
  diseased 
  sweet 
  potatoes, 
  but 
  pure 
  

   cultures 
  of 
  Rhizopus 
  were 
  made 
  in 
  flasks 
  with 
  sterilized 
  

   orange 
  and 
  lemon 
  juice 
  as 
  a 
  medium. 
  After 
  several 
  weeks 
  

   the 
  culture 
  medium 
  was 
  decanted 
  ofT, 
  filtered 
  and 
  treated 
  

   with 
  alcohol. 
  A 
  flocculent 
  gray 
  precipitate 
  was 
  immediately 
  

   formed 
  which 
  was 
  similar 
  in 
  appearance 
  to 
  that 
  obtained 
  di- 
  

   rectly 
  from 
  the 
  sweet 
  potato, 
  and 
  proved 
  to 
  have 
  the 
  same 
  

   destructive 
  properties. 
  

  

  I 
  have 
  been 
  able 
  to 
  get 
  a 
  similar, 
  if 
  not 
  identical, 
  substance, 
  

   not 
  only 
  from 
  the 
  lily 
  Botrytis, 
  but 
  also 
  from 
  another 
  Botry- 
  

   tis 
  growing 
  upon 
  the 
  common 
  live-forever 
  (Sedum 
  telephium). 
  

   j^esides 
  which 
  I 
  have 
  found 
  that 
  if 
  leaves 
  of 
  potato 
  infested 
  with 
  

   fhytophthora 
  infestans 
  (Peronospora 
  infestans) 
  be 
  crushed 
  

   in 
  a 
  mortar 
  with 
  a 
  little 
  water, 
  and 
  the 
  liquid 
  poured 
  off 
  and 
  

   treated 
  with 
  alcohol, 
  a 
  similar 
  precipitate 
  is 
  formed 
  having 
  

   similar 
  properties. 
  In 
  the 
  cases 
  of 
  Rhizopus, 
  the 
  lily 
  Botry- 
  

   "s, 
  and 
  the 
  Botrytis 
  on 
  Sedum, 
  I 
  think 
  I 
  have 
  been 
  able 
  to 
  show 
  

   ^onclusivelv 
  that 
  the 
  facultative 
  disease 
  agent 
  is 
  a 
  chemical 
  

   oiie. 
  Marshall-Ward 
  has 
  shown 
  it 
  to 
  be 
  true 
  of 
  the 
  lily 
  

   ^otrytis, 
  while 
  De 
  Bary 
  before 
  him 
  showed 
  it 
  to 
  be 
  so 
  in 
  

   ^clerotinia. 
  From 
  analogv, 
  having 
  obtained 
  a 
  similar 
  fer- 
  

   jnent 
  tiom 
  Phytophthora, 
  I 
  think 
  it 
  but 
  natural 
  to 
  conclude 
  

   tnat 
  here 
  again 
  we 
  have 
  another 
  case 
  of 
  this 
  method 
  of 
  

   growth. 
  

  

  These 
  fungi 
  can 
  not 
  be 
  called 
  true 
  parasites 
  for 
  their 
  

   naanner 
  of 
  growing 
  is 
  very 
  distinctly 
  saprophytic, 
  the 
  fer- 
  

  

  