﻿Selection 
  of 
  Elementary 
  Species 
  101 
  

  

  Europe 
  from 
  whence 
  it 
  has 
  been 
  introduced 
  in 
  

   the 
  United 
  States. 
  In 
  summers 
  which 
  are 
  un- 
  

   favorable 
  to 
  the 
  development 
  of 
  the 
  cultivated 
  

   oats 
  it 
  may 
  be 
  observed 
  to 
  multiply 
  with 
  an 
  al- 
  

   most 
  incredible 
  rapidity. 
  It 
  does 
  not 
  contrib- 
  

   ute 
  to 
  the 
  harvest, 
  and 
  is 
  quite 
  useless. 
  If 
  no 
  

   selection 
  were 
  made, 
  or 
  if 
  selection 
  were 
  dis- 
  

   continued, 
  it 
  would 
  readily 
  supplant 
  the 
  culti- 
  

   vated 
  varieties. 
  

  

  From 
  these 
  several 
  observations 
  and 
  experi- 
  

   ments 
  it 
  may 
  be 
  seen, 
  that 
  it 
  is 
  not 
  at 
  all 
  easy 
  

   to 
  keep 
  the 
  common 
  varieties 
  of 
  cereals 
  pure 
  

   and 
  that 
  even 
  the 
  best 
  are 
  subject 
  to 
  the 
  en- 
  

   croachment 
  of 
  impurities. 
  Hence 
  it 
  is 
  only 
  

   natural 
  that 
  races 
  of 
  cereals, 
  when 
  cultivated 
  

   without 
  the 
  utmost 
  care, 
  or 
  even 
  when 
  selected 
  

   without 
  an 
  exact 
  knowledge 
  of 
  their 
  single 
  con- 
  

   stituents, 
  are 
  always 
  observed 
  to 
  be 
  more 
  or 
  

   less 
  in 
  a 
  mixed 
  condition. 
  Here, 
  as 
  everywhere 
  

   with 
  cultivated 
  and 
  wild 
  plants, 
  the 
  systematic 
  

   species 
  consist 
  of 
  a 
  number 
  of 
  minor 
  types, 
  

   which 
  pertain 
  to 
  different 
  countries 
  and 
  cli- 
  

   mates, 
  and 
  are 
  growing 
  together 
  in 
  the 
  same 
  

   climate 
  and 
  under 
  the 
  same 
  external 
  conditions. 
  

   They 
  do 
  not 
  mingle, 
  nor 
  are 
  their 
  differentiat- 
  

   ing 
  characters 
  destroyed 
  by 
  intercrossing. 
  

   They 
  each 
  remain 
  pure, 
  and 
  may 
  be 
  isolated 
  

   whenever 
  and 
  wherever 
  the 
  desirability 
  for 
  

   such 
  a 
  proceeding 
  should 
  arise. 
  The 
  purity 
  of 
  

  

  