﻿NATURAL 
  RUBBER 
  — 
  COOK 
  375 
  

  

  making 
  it 
  possible 
  for 
  our 
  industrial 
  and 
  cultural 
  transformations 
  to 
  

   go 
  forward 
  with 
  such 
  amazing 
  speed. 
  It 
  might 
  be 
  said 
  that 
  Ridley 
  

   turned 
  on 
  the 
  rubber, 
  and 
  caused 
  an 
  industrial 
  deluge. 
  

  

  EXPLAINING 
  THE 
  WOUND 
  RESPONSE 
  

  

  Studies 
  of 
  the 
  tapping 
  problems 
  of 
  the 
  Para 
  rubber 
  tree 
  in 
  the 
  

   early 
  period 
  were 
  confused 
  by 
  a 
  special 
  theory 
  of 
  wound 
  response, 
  

   devised 
  to 
  explain 
  the' 
  gradually 
  increasing 
  flows 
  of 
  latex 
  after 
  the 
  

   first 
  tapping, 
  which 
  usually 
  yields 
  very 
  little. 
  The 
  theory 
  assumed 
  

   a 
  greater 
  intensity 
  of 
  physiological 
  action 
  to 
  account 
  for 
  more 
  latex 
  

   being 
  formed 
  in 
  the 
  bark 
  adjacent 
  to 
  a 
  tapping 
  wound, 
  but 
  such 
  a 
  

   reaction 
  is 
  not 
  indicated. 
  The 
  underlying 
  causes, 
  determined 
  by 
  

   later 
  investigators, 
  are 
  the 
  branching 
  latex 
  tubes, 
  which 
  form 
  a 
  con- 
  

   tinuous 
  network 
  throughout 
  the 
  bark, 
  and 
  the 
  fact 
  that 
  the 
  latex 
  

   becomes 
  more 
  liquid 
  with 
  a 
  lower 
  content 
  of 
  rubber. 
  Subsequent 
  

   tappings 
  produce 
  a 
  freer 
  flow 
  because 
  the 
  tubes 
  adjacent 
  to 
  the 
  

   wound 
  are 
  gradually 
  freed 
  of 
  the 
  thicker, 
  more 
  creamy 
  latex 
  shown 
  

   in 
  its 
  original 
  state 
  at 
  the 
  first 
  tapping; 
  other 
  changes, 
  of 
  a 
  nature 
  

   to 
  form 
  more 
  latex 
  in 
  the 
  tissues 
  around 
  the 
  wound, 
  are 
  not 
  indicated. 
  

  

  Instead 
  of 
  an 
  effect 
  of 
  the 
  tapping 
  upon 
  the 
  adjacent 
  tissues, 
  the 
  

   lack 
  of 
  such 
  an 
  effect 
  is 
  the 
  remarkable 
  fact 
  that 
  needs 
  to 
  be 
  appre- 
  

   ciated 
  in 
  order 
  to 
  understand 
  that 
  in 
  the 
  Para 
  rubber 
  tree 
  renewal 
  of 
  

   the 
  same 
  wound 
  may 
  be 
  repeated 
  frequently 
  and 
  continued 
  indefi- 
  

   nitely. 
  Because 
  the 
  latex 
  tubes 
  are 
  united 
  into 
  a 
  network, 
  the 
  supply 
  

   of 
  latex 
  is 
  always 
  sufficient 
  to 
  replenish 
  the 
  tubes 
  near 
  the 
  wound, 
  

   and 
  thus 
  to 
  restore 
  the 
  bark 
  pressure. 
  The 
  entire 
  system 
  of 
  the 
  tree 
  

   contributes 
  to 
  the 
  drainage 
  from 
  the 
  tapping 
  wound. 
  The 
  prompt 
  

   replacement 
  of 
  the 
  latex 
  and 
  renewal 
  of 
  the 
  bark 
  may 
  be 
  viewed 
  as 
  

   a 
  remarkable 
  provision 
  of 
  the 
  tree 
  against 
  the 
  wound 
  reactions 
  that 
  

   otherwise 
  might 
  occur 
  if 
  the 
  tissues 
  remained 
  depleted 
  or 
  became 
  

   infected 
  by 
  fungi 
  or 
  bacteria, 
  which 
  rarely 
  happens. 
  3 
  

  

  COMMERCIAL 
  SURVEYS 
  OF 
  WILD 
  RUBBER 
  

  

  From 
  the 
  commercial 
  standpoint 
  it 
  appeared 
  that 
  the 
  search 
  for 
  

   resources 
  of 
  wild 
  rubber 
  had 
  been 
  carried 
  to 
  a 
  practical 
  conclusion 
  

   in 
  the 
  later 
  decades 
  of 
  the 
  last 
  century. 
  With 
  supplies 
  of 
  wild 
  rub- 
  

   ber 
  from 
  Brazil 
  becoming 
  inadequate, 
  large 
  expenditures 
  were 
  made 
  

   by 
  commercial 
  agencies 
  in 
  exploring 
  the 
  tropical 
  forest 
  regions 
  of 
  

   both 
  hemispheres. 
  In 
  Africa, 
  Madagascar, 
  and 
  Malaya, 
  many 
  new 
  

   rubber-bearing 
  trees, 
  vines, 
  and 
  "root-rubbers" 
  were 
  found 
  and 
  rap- 
  

   idly 
  exhausted, 
  though 
  several 
  were 
  exploited 
  extensively 
  during 
  

  

  *A 
  lack 
  of 
  wound 
  response 
  In 
  an 
  experiment 
  with 
  repeated 
  tapping 
  was 
  re«ognized 
  by 
  

   Karling 
  in 
  a 
  latex-bearing 
  tree 
  (Couma 
  guatemalenste) 
  , 
  studied 
  in 
  eastern 
  Guatemala 
  as 
  

   a 
  possible 
  substitute 
  for 
  chicle. 
  See 
  Amer. 
  Journ. 
  Bot., 
  vol. 
  22, 
  p. 
  580, 
  1933. 
  

  

  