﻿NATURAL 
  RUBBER 
  — 
  COOK 
  399 
  

  

  lands 
  in 
  northeastern 
  Mexico 
  and 
  the 
  adjacent 
  Big 
  Bend 
  area 
  of 
  west- 
  

   ern 
  Texas. 
  Greater 
  contrasts 
  than 
  actually 
  exist 
  between 
  this 
  rubber 
  

   shrub 
  of 
  the 
  open 
  deserts 
  and 
  the 
  rubber 
  trees 
  of 
  the 
  tropical 
  forests 
  

   would 
  be 
  difficult 
  to 
  imagine. 
  The 
  only 
  resemblance 
  lies 
  in 
  the 
  

   presence 
  of 
  rubber, 
  and 
  even 
  in 
  this 
  feature 
  there 
  is 
  no 
  similarity, 
  since 
  

   guayule 
  does 
  not 
  have 
  latex, 
  but 
  forms 
  its 
  rubber 
  in 
  separate 
  cells 
  of 
  

   the 
  bark. 
  

  

  Guayule 
  is 
  one 
  of 
  many 
  low, 
  compact, 
  woody 
  shrubs 
  with 
  small 
  gray- 
  

   ish 
  leaves, 
  forming 
  one 
  of 
  the 
  principal 
  types 
  of 
  desert 
  vegetation, 
  as 
  

   appropriate 
  under 
  the 
  desert 
  conditions 
  as 
  are 
  the 
  tall, 
  spreading 
  trees 
  

   to 
  the 
  conditions 
  of 
  tropical 
  forests. 
  Hundreds 
  of 
  similar 
  grayish 
  

   shrubs 
  have 
  developed 
  in 
  desert 
  areas 
  in 
  different 
  parts 
  of 
  the 
  world, 
  

   alike 
  in 
  general 
  form 
  and 
  appearance, 
  but 
  showing 
  unlimited 
  diversi- 
  

   ties 
  in 
  structural 
  features 
  and 
  derived 
  from 
  many 
  different 
  families 
  

   of 
  plants. 
  Guayule 
  stands 
  apart 
  from 
  other 
  rubber 
  plants 
  in 
  its 
  rela- 
  

   tionships 
  as 
  a 
  member 
  of 
  the 
  thistle 
  family, 
  not 
  of 
  the 
  lettuce 
  or 
  chic- 
  

   ory 
  family, 
  which 
  also 
  have 
  rubber 
  but 
  in 
  the 
  form 
  of 
  latex. 
  The 
  dis- 
  

   covery 
  of 
  rubber 
  in 
  guayule 
  doubtless 
  was 
  made 
  long 
  ago, 
  since 
  the 
  

   natives 
  of 
  northern 
  Mexico 
  relied 
  on 
  guayule 
  rubber 
  for 
  making 
  the 
  

   rubber 
  balls 
  used 
  in 
  traditional 
  games 
  and 
  ceremonies. 
  The 
  natives 
  

   extracted 
  the 
  rubber 
  by 
  chewing 
  the 
  guayule 
  bark. 
  The 
  presence 
  of 
  

   guayule 
  in 
  Texas 
  was 
  learned 
  from 
  finding 
  balls 
  of 
  rubber 
  as 
  obstruc- 
  

   tions 
  in 
  the 
  stomachs 
  of 
  range 
  cattle 
  that 
  had 
  died 
  suddenly. 
  

  

  Little 
  has 
  come 
  to 
  light 
  regarding 
  the 
  early 
  development 
  of 
  a 
  guay- 
  

   ule 
  industry, 
  first 
  as 
  an 
  export 
  trade 
  that 
  had 
  reached 
  a 
  practical 
  scale 
  

   before 
  1902 
  preceding 
  the 
  development 
  and 
  use 
  of 
  machinery 
  for 
  ex- 
  

   tracting 
  guayule 
  rubber 
  in 
  Mexico, 
  and 
  later 
  in 
  western 
  Texas, 
  at 
  

   Marathon. 
  The 
  photograph 
  reproduced 
  in 
  plate 
  13 
  shows 
  a 
  quantity 
  

   of 
  baled 
  guayule 
  in 
  a 
  storage 
  yard 
  at 
  San 
  Luis 
  Potosi, 
  in 
  June 
  1902. 
  

  

  No 
  other 
  experimental 
  undertaking 
  by 
  private 
  interests 
  in 
  the 
  field 
  

   of 
  applied 
  botany 
  has 
  been 
  carried 
  so 
  far. 
  With 
  the 
  specialized 
  meth- 
  

   ods 
  and 
  machinery 
  it 
  appeared 
  that 
  costs 
  of 
  production 
  might 
  be 
  

   brought 
  down 
  to 
  20 
  cents 
  or 
  less 
  per 
  pound, 
  in 
  the 
  period 
  before 
  the 
  

   price 
  of 
  plantation 
  rubber 
  declined 
  to 
  that 
  level. 
  Even 
  with 
  Para 
  rub- 
  

   ber 
  at 
  15 
  cents 
  or 
  less, 
  the 
  demand 
  for 
  guayule 
  as 
  a 
  compounding 
  in- 
  

   gredient 
  provided 
  a 
  market 
  for 
  the 
  limited 
  quantity 
  that 
  was 
  obtain- 
  

   able. 
  A 
  limiting 
  factor 
  in 
  California 
  was 
  the 
  advance 
  of 
  land 
  values 
  

   to 
  a 
  point 
  too 
  high 
  for 
  the 
  development 
  of 
  a 
  large 
  guayule 
  industry. 
  

   In 
  Texas, 
  where 
  large 
  areas 
  of 
  low-priced 
  land 
  were 
  available, 
  guayule 
  

   proved 
  to 
  be 
  susceptible 
  to 
  the 
  root-rot 
  disease, 
  caused 
  by 
  a 
  fungus 
  that 
  

   lives 
  in 
  the 
  soil 
  and 
  is 
  often 
  destructive 
  to 
  cotton 
  and 
  other 
  crops. 
  

   The 
  factory 
  at 
  Marathon 
  closed 
  in 
  1926, 
  but 
  was 
  reported 
  in 
  November 
  

   1943 
  as 
  opened 
  for 
  emergency 
  production, 
  using 
  the 
  wild 
  guayule 
  in 
  

   the 
  Big 
  Bend 
  district. 
  

  

  