﻿206 
  Retrograde 
  Varieties 
  

  

  attained 
  a 
  height 
  of 
  12 
  feet, 
  but 
  the 
  season 
  did 
  

   not 
  allow 
  its 
  seeds 
  to 
  ripen 
  normally. 
  Only 
  

   a 
  few 
  kernels 
  were 
  developed 
  before 
  the 
  winter. 
  

   From 
  this 
  seed 
  plants 
  of 
  a 
  wholly 
  different 
  

   type 
  came 
  the 
  next 
  year, 
  of 
  smaller 
  stature, 
  and 
  

   with 
  more 
  brownish 
  and 
  rounded 
  kernels. 
  They 
  

   also 
  flowered 
  earlier 
  and 
  ripened 
  a 
  large 
  num- 
  

   ber 
  of 
  seeds. 
  The 
  depression 
  on 
  the 
  outer 
  side 
  

   of 
  the 
  seed 
  had 
  almost 
  disappeared, 
  and 
  the 
  

   original 
  white 
  had 
  become 
  darker. 
  Some 
  of 
  the 
  

   seeds 
  had 
  even 
  become 
  yellow 
  and 
  in 
  their 
  

   rounded 
  form 
  they 
  approached 
  the 
  common 
  

   European 
  maize. 
  Obviously 
  they 
  were 
  hybrids, 
  

   assuming 
  the 
  character 
  of 
  their 
  pollen-parent, 
  

   which 
  evidently 
  was 
  the 
  ordinary 
  corn, 
  culti- 
  

   vated 
  all 
  around. 
  The 
  observation 
  of 
  the 
  next 
  

   year 
  showed 
  this 
  clearly, 
  for 
  in 
  the 
  third 
  gener- 
  

   ation 
  nearly 
  all 
  resemblance 
  to 
  the 
  original 
  and 
  

   very 
  distinct 
  American 
  species 
  was 
  lost. 
  If 
  

   we 
  assume 
  that 
  only 
  those 
  seeds 
  ripened 
  which 
  

   reverted 
  to 
  the 
  early-ripening 
  European 
  type, 
  

   and 
  that 
  those 
  that 
  remained 
  true 
  to 
  the 
  very 
  

   late 
  American 
  variety 
  could 
  not 
  reach 
  maturity, 
  

   the 
  case 
  seems 
  to 
  be 
  wholly 
  comprehensible, 
  

   without 
  supposing 
  any 
  other 
  factors 
  to 
  have 
  

   been 
  at 
  work 
  than 
  those 
  of 
  vicinism, 
  which 
  

   though 
  unknown 
  at 
  the 
  period 
  of 
  Metzger 
  's 
  and 
  

   Darwin's 
  writings, 
  seems 
  now 
  to 
  be 
  fully 
  un- 
  

   derstood. 
  No 
  innate 
  tendency 
  to 
  run 
  out 
  and 
  

  

  