﻿New 
  Species 
  of 
  Oenothera 
  517 
  

  

  systematic 
  affinities 
  at 
  large. 
  Many 
  authors 
  

   have 
  tried 
  to 
  solve 
  it 
  on 
  the 
  ground 
  of 
  compara- 
  

   tive 
  studies 
  and 
  of 
  speculations 
  upon 
  the 
  bio- 
  

   logic 
  relations 
  of 
  plants 
  and 
  animals. 
  But 
  in 
  

   vain. 
  Contradiction 
  and 
  doubt 
  still 
  reign 
  su- 
  

   preme. 
  All 
  our 
  hopes 
  now 
  rest 
  on 
  the 
  result 
  of 
  

   experiments. 
  

  

  Unfortunately 
  such 
  experiments 
  seemed 
  sim- 
  

   ply 
  impossible 
  a 
  few 
  years 
  ago. 
  What 
  is 
  to 
  

   guide 
  us 
  in 
  the 
  choice 
  of 
  the 
  material 
  ? 
  The 
  

   answer 
  may 
  only 
  be 
  expected 
  from 
  a 
  consid- 
  

   eration 
  of 
  elementary 
  species. 
  For 
  it 
  is 
  obvious 
  

   that 
  they 
  only 
  can 
  be 
  observed 
  to 
  originate, 
  and 
  

   that 
  the 
  systematic 
  species, 
  because 
  they 
  are 
  

   only 
  artificial 
  groups 
  of 
  lower 
  unities, 
  can 
  never 
  

   become 
  the 
  subject 
  of 
  successful 
  experimental 
  

   inquiry. 
  

  

  In 
  previous 
  lectures 
  we 
  tried 
  to 
  clear 
  up 
  the 
  

   differences 
  existing 
  between 
  nearly 
  related 
  ele- 
  

   mentary 
  species. 
  We 
  have 
  seen 
  that 
  they 
  af- 
  

   fect 
  all 
  of 
  the 
  attributes 
  of 
  the 
  plants, 
  each 
  of 
  

   them 
  changing 
  in 
  some 
  measure 
  all 
  of 
  the 
  or- 
  

   gans. 
  Nevertheless 
  they 
  were 
  due 
  to 
  distinct 
  

   unities 
  and 
  of 
  the 
  lowest 
  possible 
  degree. 
  Such 
  

   unit-steps 
  may 
  therefore 
  be 
  expected 
  to 
  become 
  

   visible 
  some 
  time 
  or 
  other 
  by 
  artificial 
  means. 
  

   On 
  the 
  other 
  hand, 
  mutations 
  as 
  a 
  rule 
  make 
  

   their 
  appearance 
  in 
  groups, 
  and 
  there 
  are 
  many 
  

   systematic 
  species 
  which 
  on 
  close 
  inspection 
  

  

  