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  Retrograde 
  Varieties 
  

  

  But 
  the 
  diversity 
  of 
  the 
  color 
  patterns 
  is 
  far 
  

   from 
  being 
  exhausted 
  with 
  these 
  simple 
  in- 
  

   stances. 
  Apart 
  from 
  them, 
  or 
  joined 
  to 
  them, 
  

   other 
  complications 
  are 
  frequently 
  seen, 
  which 
  

   it 
  is 
  impossible 
  to 
  analyze 
  in 
  such 
  an 
  artificial 
  

   way. 
  Here 
  we 
  have 
  to 
  return 
  to 
  our 
  former 
  

   principle, 
  the 
  comparison 
  of 
  different 
  varieties. 
  

   Assuming 
  that 
  single 
  units 
  may 
  be 
  lost, 
  ir- 
  

   respective 
  of 
  the 
  others, 
  we 
  may 
  expect 
  to 
  find 
  

   them 
  segregated 
  by 
  variation, 
  wherever 
  a 
  suffi- 
  

   ciently 
  wide 
  range 
  of 
  color-varieties 
  is 
  in 
  culti- 
  

   vation. 
  In 
  fact, 
  in 
  most 
  cases 
  a 
  high 
  degree 
  of 
  

   dissimilarity 
  may 
  be 
  reached 
  in 
  the 
  simplest 
  

   way 
  by 
  such 
  a 
  separation 
  of 
  the 
  components, 
  

   and 
  by 
  their 
  combination 
  into 
  most 
  diverse 
  

   smaller 
  groups. 
  A 
  very 
  nice 
  instance 
  of 
  such 
  

   an 
  analysis 
  of 
  flower-colors 
  is 
  afforded 
  by 
  the 
  

   ordinary 
  snapdragon. 
  The 
  beautiful 
  brown- 
  

   red 
  color 
  of 
  this 
  common 
  garden-plant 
  is 
  com- 
  

   posed 
  on 
  one 
  side 
  of 
  yellow 
  elements, 
  on 
  the 
  

   other 
  of 
  red 
  units. 
  Of 
  the 
  yellow 
  there 
  are 
  

   two, 
  one 
  staining 
  the 
  whole 
  corolla 
  with 
  a 
  light 
  

   hue, 
  as 
  is 
  to 
  be 
  seen 
  in 
  the 
  pure 
  yellow 
  variety 
  

   called 
  luteum. 
  This 
  form 
  has 
  been 
  produced 
  

   by 
  the 
  loss 
  of 
  the 
  whole 
  group 
  of 
  the 
  red 
  con- 
  

   stituents. 
  If 
  the 
  yellow 
  tinge 
  is 
  also 
  lost, 
  there 
  

   arises 
  a 
  white 
  variety, 
  but 
  this 
  is 
  not 
  absolutely 
  

   colorless, 
  but 
  shows 
  the 
  other 
  yellow 
  constit- 
  

   uent. 
  This 
  last 
  stains 
  only 
  some 
  small 
  parts 
  

  

  