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  Mutations 
  

  

  be 
  chosen 
  in 
  order 
  to 
  get 
  the 
  new 
  type 
  in 
  its 
  pure 
  

   condition. 
  Nothing 
  of 
  the 
  kind, 
  however, 
  was 
  

   observed. 
  All 
  the 
  oblong 
  a-mutants 
  were 
  pure 
  

   oblongas. 
  The 
  pedigree 
  shows 
  hundreds 
  of 
  

   them 
  in 
  the 
  succeeding 
  years, 
  but 
  no 
  difference 
  

   was 
  seen 
  and 
  no 
  material 
  for 
  selection 
  was 
  af- 
  

   forded. 
  All 
  were 
  as 
  nearly 
  equal 
  as 
  the 
  in- 
  

   dividuals 
  of 
  old 
  elementary 
  species. 
  

  

  II. 
  New 
  forms 
  spring 
  laterally 
  from 
  the 
  

   main 
  stem. 
  

  

  The 
  current 
  conception 
  concerning 
  the 
  origin 
  

   of 
  species 
  assumes 
  that 
  species 
  are 
  slowly 
  con- 
  

   verted 
  into 
  others. 
  The 
  conversion 
  is 
  assumed 
  

   to 
  affect 
  all 
  the 
  individuals 
  in 
  the 
  same 
  direction 
  

   and 
  in 
  the 
  same 
  degree. 
  The 
  whole 
  group 
  

   changes 
  its 
  character, 
  acquiring 
  new 
  attributes. 
  

   By 
  inter-crossing 
  they 
  maintain 
  a 
  common 
  line 
  

   of 
  progress, 
  one 
  individual 
  never 
  being 
  able 
  to 
  

   proceed 
  much 
  ahead 
  of 
  the 
  others. 
  

  

  The 
  birth 
  of 
  the 
  new 
  species 
  necessarily 
  

   seemed 
  to 
  involve 
  the 
  death 
  of 
  the 
  old 
  one. 
  This 
  

   last 
  conclusion, 
  however, 
  is 
  hard 
  to 
  understand. 
  

   It 
  may 
  be 
  justifiable 
  to 
  assume 
  that 
  all 
  the 
  in- 
  

   dividuals 
  of 
  one 
  locality 
  are 
  ordinarily 
  inter- 
  

   crossed, 
  and 
  are 
  moreover 
  subjected 
  to 
  the 
  same 
  

   external 
  conditions. 
  They 
  might 
  be 
  supposed 
  

   to 
  vary 
  in 
  the 
  same 
  direction 
  if 
  these 
  conditions 
  

   were 
  changed 
  slowly. 
  But 
  this 
  could 
  of 
  course 
  

   have 
  no 
  possible 
  influence 
  on 
  the 
  plants 
  of 
  the 
  

  

  