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  Retrograde 
  Varieties 
  

  

  sharp 
  limits 
  between 
  nearly 
  related 
  characters 
  

   must 
  suffice. 
  As 
  Bateson 
  has 
  put 
  it, 
  species 
  are 
  

   discontinuous, 
  and 
  we 
  must 
  assume 
  that 
  their 
  

   characters 
  are 
  discontinuous 
  also. 
  

  

  Moreover 
  there 
  is 
  as 
  yet 
  no 
  reason 
  for 
  trying 
  

   to 
  make 
  a 
  complete 
  analysis 
  of 
  all 
  the 
  charac- 
  

   ters 
  of 
  a 
  plant. 
  No 
  doubt, 
  if 
  attained, 
  such 
  an 
  

   analysis 
  would 
  give 
  us 
  a 
  deep 
  insight 
  into 
  the 
  

   real 
  internal 
  construction 
  of 
  the 
  intricate 
  prop- 
  

   erties 
  of 
  organisms 
  in 
  general. 
  But 
  taxonomic 
  

   studies 
  in 
  this 
  direction 
  are 
  only 
  in 
  their 
  in- 
  

   fancy 
  and 
  do 
  not 
  give 
  us 
  the 
  material 
  required 
  

   for 
  such 
  an 
  analysis. 
  Quite 
  on 
  the 
  contrary, 
  

   they 
  compel 
  us 
  to 
  confine 
  our 
  study 
  to 
  the 
  most 
  

   recently 
  acquired, 
  or 
  youngest 
  characters, 
  

   which 
  constitute 
  the 
  differentiating 
  marks 
  be- 
  

   tween 
  nearly 
  allied 
  forms. 
  

  

  Obviously 
  this 
  is 
  especially 
  the 
  case 
  in 
  the 
  

   realm 
  of 
  the 
  hybrids, 
  since 
  only 
  nearly 
  related 
  

   forms 
  are 
  able 
  to 
  give 
  hybrid 
  offspring. 
  In 
  

   dealing 
  with 
  this 
  subject 
  we 
  must 
  leave 
  aside 
  

   all 
  questions 
  concerning 
  more 
  remote 
  relation- 
  

   ships. 
  

  

  It 
  is 
  not 
  my 
  purpose 
  to 
  treat 
  of 
  the 
  doctrine 
  

   of 
  hybridization 
  at 
  any 
  length. 
  Experience 
  is 
  

   so 
  rapidly 
  increasing 
  both 
  in 
  a 
  practical 
  

   and 
  in 
  a 
  purely 
  scientific 
  direction 
  that 
  it 
  would 
  

   take 
  an 
  entire 
  volume 
  to 
  give 
  only 
  a 
  brief 
  sur- 
  

   vey 
  of 
  the 
  facts 
  and 
  of 
  all 
  the 
  proposed 
  theories. 
  

  

  