﻿38 
  

  

  eases 
  of 
  the 
  disease 
  found 
  in 
  the 
  Arnold 
  Arboretum. 
  On 
  the 
  west, 
  we 
  

   have 
  two 
  cases 
  in 
  West 
  Virginia, 
  and 
  the 
  most 
  southern 
  station 
  which 
  

   I 
  know 
  of 
  is 
  in 
  Bedford 
  County, 
  Virginia. 
  But 
  those 
  are 
  isolated 
  sta- 
  

   tions 
  beyond 
  the 
  area 
  which 
  is 
  indicated 
  here. 
  I 
  shall 
  have 
  a 
  little 
  

   more 
  to 
  say 
  in 
  regard 
  to 
  the 
  distribution.. 
  

  

  Before 
  speaking 
  of 
  that, 
  I 
  want 
  to 
  call 
  your 
  attention 
  to 
  a 
  few 
  

   points 
  in 
  regard 
  to 
  fungi 
  in 
  gen(?ral, 
  points 
  of 
  common 
  knowledge 
  to 
  

   all 
  who 
  have 
  studied 
  fungi 
  or 
  mycology. 
  A 
  fungus 
  is 
  a 
  kind 
  of 
  plant 
  

   which 
  does 
  not, 
  on 
  account 
  of 
  the 
  absence 
  of 
  the 
  green 
  coloring 
  matter, 
  

   manufacture 
  its 
  own 
  food. 
  It 
  is 
  a 
  plant 
  which 
  has, 
  in 
  other 
  words, 
  no 
  

   green 
  foliage, 
  and 
  as 
  it 
  has 
  no 
  green 
  foliage, 
  it 
  must 
  obtain 
  its 
  organic 
  

   or 
  elaborated 
  food 
  from 
  some 
  other 
  source. 
  The 
  fungi 
  have 
  very 
  aptly 
  

   been 
  termed 
  the 
  tramps 
  of 
  the 
  vegetable 
  kingdom, 
  that 
  is, 
  they 
  live 
  on 
  

   food 
  prepared 
  by 
  somebody 
  else. 
  They 
  can 
  take 
  certain 
  organic 
  sub- 
  

   stances 
  and 
  change 
  them 
  apparently 
  into 
  other 
  organic 
  matter 
  which 
  

   can 
  be 
  used 
  by 
  the 
  plant. 
  In 
  the 
  case 
  of 
  this 
  chestnut 
  fiuigus, 
  we 
  have 
  

   a 
  fairly 
  typical 
  fungus 
  in 
  certain 
  respects. 
  "We 
  have 
  a 
  vegetative 
  stage 
  

   of 
  the 
  fungus 
  which 
  is 
  nothing 
  more 
  or 
  less 
  than 
  a 
  lot 
  of 
  threadlike 
  

   structures 
  penetrating 
  the 
  bark 
  of 
  the 
  chestnut, 
  the 
  inner 
  bark 
  or 
  the 
  

   middle 
  bark, 
  and 
  there 
  drawing 
  the 
  organic 
  matter 
  from 
  the 
  bark 
  of 
  

   the 
  chestnut 
  and 
  appropriating 
  it 
  to 
  its 
  own 
  use. 
  Fungi, 
  like 
  practi- 
  

   cally 
  all 
  other 
  plants, 
  have 
  two 
  stages 
  of 
  existence, 
  one 
  the 
  vegetative 
  or 
  

   growing 
  stage, 
  the 
  other 
  the 
  reproductive 
  stage. 
  Sooner 
  or 
  later 
  the 
  

   fungus 
  will 
  produce 
  the 
  fruiting 
  bodies, 
  after 
  it 
  has 
  obtained 
  a 
  sufficient 
  

   amount 
  of 
  food 
  to 
  justify 
  the 
  formation 
  of 
  these 
  more 
  highly 
  organized 
  

   structures. 
  In 
  the 
  case 
  of 
  the 
  fruiting 
  body 
  of 
  the 
  chestnut 
  fungus, 
  we 
  

   have 
  very 
  small, 
  pinhead-like 
  structures, 
  which 
  come 
  out 
  to 
  the 
  surface 
  

   of 
  the 
  bark, 
  the 
  vegetative 
  portion 
  developing 
  through 
  the 
  interior 
  of 
  

   the 
  bark. 
  On 
  smooth 
  bark 
  we 
  find 
  that 
  these 
  fruiting 
  pustules 
  are 
  apt 
  

   to 
  appear 
  all 
  over 
  the 
  surface. 
  With 
  bark 
  that 
  is 
  sufficiently 
  old 
  to 
  

   have 
  ridges 
  and 
  crevices, 
  we 
  find 
  these 
  fruiting 
  bodies 
  only 
  in 
  the 
  

   crevices. 
  

  

  These 
  fruiting 
  pustules 
  which 
  you 
  will 
  see 
  on 
  this 
  bark 
  are 
  the 
  

   structures 
  which 
  produce 
  the 
  reproductive 
  bodies, 
  these 
  latter 
  being 
  

   known 
  as 
  the 
  spores. 
  There 
  are 
  two 
  types 
  of 
  spores 
  which 
  are 
  produced 
  

   by 
  this 
  fungus. 
  One 
  is 
  the 
  type 
  which 
  is 
  commonly 
  spoken 
  of 
  as 
  the 
  

   summer 
  spore, 
  the 
  other 
  the 
  type 
  which 
  is 
  spoken 
  of 
  as 
  the 
  winter 
  

   spore. 
  The 
  winter 
  spore 
  is 
  known 
  from 
  the 
  point 
  of 
  view 
  of 
  the 
  

   mycologist 
  as 
  the 
  perfect 
  stage 
  of 
  the 
  fungus, 
  that 
  is, 
  it 
  is 
  the 
  more 
  

   characteristic 
  of 
  this 
  particular 
  fungus. 
  If 
  we 
  should 
  make 
  a 
  cross 
  

   section 
  of 
  the 
  bark, 
  we 
  should 
  tind 
  that 
  the 
  vegetative 
  stage 
  is 
  running 
  

   through 
  the 
  middle 
  bark, 
  and 
  commonly 
  the 
  inner 
  bark, 
  sometimes 
  in 
  

   one 
  place 
  only, 
  sometimes 
  in 
  the 
  other 
  only, 
  sometimes 
  in 
  both. 
  This 
  

  

  