﻿334 
  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  advanced 
  quite 
  far 
  as 
  can 
  be 
  seen 
  by 
  the 
  new 
  growth 
  all 
  around 
  

   the 
  edge 
  of 
  the 
  wound. 
  

  

  How 
  the 
  tree 
  is 
  killed. 
  — 
  Two 
  years 
  ago 
  when 
  I 
  first 
  observed 
  this 
  

   tree 
  though 
  it 
  was 
  still 
  alive, 
  a 
  number 
  of 
  the 
  top 
  limbs 
  were 
  dead. 
  

   This 
  suggested 
  that 
  the 
  rot 
  caused 
  by 
  the 
  fungus 
  extended 
  entirely 
  

   through 
  the 
  tree. 
  To 
  determine 
  this 
  question, 
  and 
  also 
  to 
  see 
  

   the 
  relation 
  of 
  the 
  fungus 
  to 
  the 
  decay, 
  as 
  well 
  as 
  to 
  determine 
  

   the 
  structural 
  peculiarities 
  produced 
  in 
  the 
  wood 
  by 
  this 
  species, 
  

   during 
  its 
  disintegrating 
  action 
  on 
  the 
  wood, 
  the 
  tree 
  was 
  felled 
  

   and 
  sawed 
  up 
  into 
  short 
  sections. 
  These 
  sections 
  were 
  then 
  split 
  

   and 
  a 
  large 
  number 
  of 
  them 
  were 
  preserved 
  for 
  examination. 
  

  

  Several 
  of 
  the 
  blocks 
  of 
  heart 
  wood 
  split 
  from 
  the 
  tree 
  were 
  

   photographed, 
  and 
  one 
  of 
  these 
  is 
  shown 
  natural 
  size 
  in 
  Plate 
  

   57. 
  The 
  white 
  strands 
  which 
  extend 
  horizontally 
  in 
  the 
  wood 
  

   are 
  the 
  strands 
  of 
  mycelium 
  which 
  is 
  the 
  vegetative 
  part 
  of 
  this 
  

   fungus. 
  It 
  corresponds 
  to 
  the 
  so-called 
  "spawn 
  " 
  of 
  the 
  mush- 
  

   room, 
  which 
  is 
  characteristic 
  of 
  all 
  the 
  members 
  of 
  the 
  fungi 
  

   belonging 
  to 
  the 
  mushroom 
  group, 
  though 
  there 
  are 
  varia- 
  

   tions 
  in 
  its 
  nature 
  and 
  extent. 
  These 
  strands 
  of 
  the 
  mycelium 
  

   are 
  composed 
  of 
  numerous 
  delicate, 
  slender 
  fungus 
  threads 
  all 
  

   woven 
  together. 
  They 
  extend 
  throughout 
  the 
  length 
  of 
  the 
  

   tree 
  in 
  the 
  heart 
  wood 
  . 
  They 
  grow 
  through 
  the 
  cell 
  wails 
  of 
  

   the 
  wood 
  and 
  cause 
  the 
  disintegration 
  of 
  the 
  latter, 
  first 
  by 
  

   opening 
  minute 
  holes 
  along 
  the 
  line 
  of 
  their 
  advance, 
  which 
  is 
  

   in 
  a 
  longitudinal, 
  radial, 
  and 
  tangential 
  direction. 
  This 
  tends 
  

   to 
  divide 
  up 
  the 
  wood 
  into 
  small 
  cubical 
  areas 
  which 
  are 
  more 
  

   pronounced 
  later 
  as 
  the 
  fungus 
  threads 
  disappear 
  and 
  the 
  wood 
  

   by 
  advanced 
  stages 
  of 
  decay 
  tends 
  to 
  collapse. 
  The 
  fungus 
  

   threads 
  have 
  the 
  property 
  of 
  excreting 
  a 
  kind 
  of 
  ferment 
  which 
  

   dissolves 
  the 
  woody 
  and 
  cellulose 
  walls, 
  thus 
  disintegrating 
  the 
  

   wood 
  and 
  opening 
  a 
  way 
  for 
  the 
  advance 
  of 
  the 
  fungus. 
  

  

  Starting; 
  of 
  the 
  ftingus 
  germ. 
  — 
  By 
  this 
  thorough 
  examination 
  

   of 
  the 
  felled 
  tree 
  it 
  is 
  possible 
  to 
  make 
  out 
  the 
  history 
  of 
  this 
  

   fungus. 
  The 
  photograph 
  in 
  Plate 
  56 
  tells 
  a 
  great 
  deal 
  of 
  the 
  

   story 
  of 
  how 
  the 
  fungus 
  was 
  able 
  to 
  get 
  inside 
  of 
  the 
  tree 
  and 
  

   then 
  to 
  grow 
  out 
  again 
  in 
  the 
  form 
  of 
  the 
  bracket 
  fruit 
  bodies. 
  

   The 
  Polyporics 
  borealis 
  is 
  not 
  a 
  parsitic 
  fungus. 
  It 
  cannot 
  make 
  

   its 
  way 
  unaided 
  through 
  the 
  sound 
  living 
  part 
  of 
  the 
  tree 
  which 
  

  

  