﻿Cultivated 
  Elementary 
  Species 
  81 
  

  

  flax 
  remain 
  closed 
  until 
  the 
  seeds 
  are 
  liberated 
  

   by 
  threshing. 
  It 
  seems 
  probable 
  that 
  the 
  first 
  

   form 
  or 
  Linum 
  crepitans 
  might 
  thrive 
  in 
  the 
  

   wild 
  state 
  as 
  well 
  as 
  any 
  other 
  plant, 
  while 
  in 
  

   the 
  common 
  species 
  those 
  qualities 
  are 
  lacking 
  

   which 
  are 
  required 
  for 
  a 
  normal 
  dissemination 
  

   of 
  the 
  seeds. 
  White 
  or 
  blue 
  flowers, 
  high 
  or 
  

   dwarf 
  stems, 
  more 
  or 
  less 
  branching 
  at 
  the 
  base 
  

   and 
  sundry 
  other 
  qualities 
  distinguish 
  the 
  va- 
  

   rieties, 
  aside 
  from 
  the 
  special 
  industrial 
  differ- 
  

   ence 
  of 
  the 
  fibres. 
  Even 
  the 
  life-history 
  varies 
  

  

  V 
  

  

  from 
  annual 
  and 
  biennial, 
  to 
  perennial. 
  

  

  It 
  would 
  take 
  us 
  too 
  long 
  to 
  consider 
  other 
  in- 
  

   stances. 
  It 
  is 
  well 
  known 
  that 
  corn, 
  though 
  

   considered 
  as 
  a 
  single 
  botanical 
  species, 
  is 
  rep- 
  

   resented 
  by 
  different 
  subspecies 
  and 
  varieties 
  

   in 
  nearly 
  every 
  region 
  in 
  which 
  it 
  is 
  grown. 
  Of 
  

   course 
  its 
  history 
  is 
  unknown 
  and 
  it 
  is 
  impossi- 
  

   ble 
  to 
  decide 
  whether 
  all 
  the 
  tall 
  and 
  dwarf 
  

   forms, 
  or 
  starchy 
  and 
  sweet 
  varieties, 
  dented 
  

   or 
  rounded 
  kernels, 
  and 
  hundreds 
  of 
  others 
  are 
  

   older 
  than 
  culture 
  or 
  have 
  come 
  into 
  existence 
  

   during 
  historic 
  times, 
  or 
  as 
  some 
  assume, 
  

   through 
  the 
  agency 
  of 
  man. 
  But 
  our 
  main 
  

   point 
  now 
  is 
  not 
  the 
  origin, 
  but 
  only 
  the 
  

   existence 
  of 
  constant 
  and 
  sharply 
  differentiated 
  

   forms 
  within 
  botanical 
  species. 
  Nearly 
  every 
  

   cultivated 
  plant 
  affords 
  instances 
  of 
  such 
  di- 
  

   versity. 
  Some 
  include 
  a 
  few 
  types 
  only, 
  while 
  

  

  