﻿Retrograde 
  Varieties 
  125 
  

  

  verna, 
  Helianthemum 
  or 
  of 
  Taraxacum; 
  all 
  

   characters 
  are 
  almost 
  equally 
  concerned. 
  The 
  

   elementary 
  species 
  of 
  Draba 
  are 
  characterized, 
  

   as 
  we 
  have 
  seen, 
  by 
  the 
  forms 
  and 
  the 
  hairiness 
  

   of 
  the 
  leaves, 
  the 
  number 
  and 
  height 
  of 
  the 
  

   flower-stalks, 
  the 
  breadth 
  and 
  incision 
  of 
  the 
  

   petals, 
  the 
  forms 
  of 
  the 
  fruits, 
  and 
  so 
  on. 
  

   Every 
  one 
  of 
  the 
  two 
  hundred 
  forms 
  included 
  

   in 
  this 
  collective 
  species 
  has 
  its 
  own 
  type, 
  which 
  

   it 
  is 
  impossible 
  to 
  express 
  by 
  a 
  single 
  term. 
  

   Their 
  names 
  are 
  chosen 
  arbitrarily. 
  Quite 
  the 
  

   contrary 
  is 
  the 
  case 
  with 
  most 
  of 
  the 
  varieties, 
  

   for 
  which 
  one 
  word 
  ordinarily 
  suffices 
  to 
  ex- 
  

   press 
  the 
  whole 
  difference. 
  

  

  White 
  varieties 
  of 
  species 
  with 
  red 
  or 
  blue 
  

   flowers 
  are 
  the 
  most 
  common 
  instances. 
  If 
  the 
  

   species 
  has 
  a 
  compound 
  color 
  and 
  if 
  only 
  one 
  

   of 
  the 
  constituents 
  is 
  lost, 
  partially 
  colored 
  

   types 
  arise 
  as 
  in 
  Agrostemma 
  Coronaria 
  bicolor. 
  

   Or 
  the 
  spots 
  may 
  disappear 
  and 
  the 
  color 
  be- 
  

   come 
  uniform 
  as 
  in 
  Gentiana 
  punctata 
  concolor 
  

   and 
  the 
  spotless 
  Arum 
  or 
  Arum 
  maculatum 
  im- 
  

   maculatum. 
  Absence 
  of 
  hairs 
  produces 
  forms 
  

   as 
  Biscutella 
  loevigata 
  glabra; 
  lack 
  of 
  prickles 
  

   gives 
  the 
  varieties 
  known 
  as 
  inermis, 
  as 
  for 
  in- 
  

   stance, 
  Ranunculus 
  arvensis 
  inermis. 
  Cytisus 
  

   prostratus 
  has 
  a 
  variety 
  ciliata, 
  and 
  Solanum 
  

   Dulcamara, 
  or 
  the 
  bitter-sweet, 
  has 
  a 
  va- 
  

   riety 
  called 
  tomentosum. 
  The 
  curious 
  mon- 
  

  

  