﻿Systematic 
  Atavism 
  641 
  

  

  veloping 
  to 
  unusual 
  size, 
  is 
  afforded 
  by 
  a 
  variety 
  

   of 
  corn, 
  which 
  is 
  called 
  Zea 
  Mays 
  cryptosperma, 
  

   or 
  Zea 
  Mays 
  tunicata. 
  In 
  ordinary 
  corn 
  the 
  

   kernels 
  are 
  surrounded 
  by 
  small 
  and 
  thin, 
  incon- 
  

   spicuous 
  and 
  membranaceous 
  scales. 
  Invisible 
  

   on 
  the 
  integrate 
  spikes, 
  when 
  ripe, 
  they 
  are 
  

   easily 
  detected 
  by 
  pulling 
  the 
  kernels 
  out. 
  In 
  

   cryptosperma 
  they 
  are 
  so 
  strongly 
  developed 
  as 
  

   to 
  completely 
  hide 
  the 
  kernels. 
  Obviously 
  they 
  

   constitute 
  a 
  case 
  of 
  reversion 
  to 
  the 
  characters 
  

   of 
  some 
  unknown 
  ancestor, 
  since 
  the 
  corn 
  is 
  the 
  

   only 
  member 
  of 
  the 
  grass-family 
  with 
  naked 
  

   kernels. 
  The 
  var. 
  tunicata, 
  for 
  this 
  same 
  rea- 
  

   son, 
  has 
  been 
  considered 
  to 
  be 
  the 
  original 
  wild 
  

   form, 
  from 
  which 
  the 
  other 
  varieties 
  of 
  corn 
  

   have 
  originated. 
  But 
  as 
  no 
  historical 
  evidence 
  

   on 
  this 
  point 
  is 
  at 
  hand, 
  we 
  must 
  leave 
  it 
  as 
  it 
  is, 
  

   notwithstanding 
  the 
  high 
  degree 
  of 
  attractive- 
  

   ness 
  attached 
  to 
  the 
  suggestion. 
  

  

  The 
  horsetail-family 
  may 
  be 
  taken 
  as 
  a 
  fur- 
  

   ther 
  support 
  of 
  our 
  assertion. 
  Some 
  species 
  

   have 
  stems 
  of 
  two 
  kinds, 
  the 
  fertile 
  being 
  

   brownish 
  and 
  appearing 
  in 
  early 
  spring 
  before 
  

   the 
  green 
  or 
  sterile 
  ones. 
  In 
  others 
  the 
  stems 
  

   are 
  all 
  alike, 
  green 
  and 
  crowned 
  with 
  a 
  cone- 
  

   like 
  spike 
  of 
  sporangia-bearing 
  scales. 
  Mani- 
  

   festly 
  the 
  dimorphous 
  cases 
  are 
  to 
  be 
  considered 
  

   as 
  the 
  younger 
  ones, 
  partly 
  because 
  they 
  are 
  

   obvious 
  exceptions 
  to 
  the 
  common 
  rule, 
  and 
  

  

  