﻿Elementary 
  Species 
  in 
  Nature 
  33 
  

  

  as 
  to 
  what 
  groups 
  are 
  real 
  units 
  and 
  will 
  remain 
  

   constant 
  and 
  unchanged 
  through 
  all 
  the 
  years 
  

   of 
  our 
  observations. 
  

  

  Before 
  Linnaeus, 
  the 
  genera 
  were 
  the 
  real 
  

   units 
  of 
  the 
  system. 
  De 
  Candolle 
  pointed 
  out 
  

   that 
  the 
  old 
  common 
  names 
  of 
  plants, 
  such 
  as 
  

   roses 
  and 
  clover, 
  poplars 
  and 
  oaks, 
  nearly 
  all 
  

   refer 
  to 
  genera. 
  The 
  type 
  of 
  the 
  clovers 
  is 
  

   rich 
  in 
  color, 
  and 
  the 
  shape 
  of 
  the 
  flower-heads 
  

   and 
  the 
  single 
  flowers 
  escape 
  ordinary 
  obser- 
  

   vation; 
  but 
  notwithstanding 
  this, 
  clovers 
  are 
  

   easily 
  recognized, 
  even 
  if 
  new 
  types 
  come 
  to 
  

   hand. 
  White 
  and 
  red 
  clovers 
  and 
  many 
  other 
  

   species 
  are 
  distinguished 
  simply 
  by 
  adjectives, 
  

   the 
  generic 
  name 
  remaining 
  the 
  same 
  for 
  all. 
  

  

  Tournefort, 
  who 
  lived 
  in 
  the 
  second 
  half 
  of 
  

   the 
  17th 
  century 
  (1656-1708), 
  is 
  generally 
  con- 
  

   sidered 
  as 
  the 
  author 
  of 
  genera 
  in 
  systematic 
  

   botany. 
  He 
  adopted, 
  what 
  was 
  at 
  that 
  time 
  

   the 
  general 
  conception 
  and 
  applied 
  it 
  through- 
  

   out 
  the 
  vegetable 
  kingdom. 
  He 
  grouped 
  the 
  

   new 
  and 
  the 
  rare 
  and 
  the 
  previously 
  over- 
  

   looked 
  forms 
  in 
  the 
  same 
  manner 
  in 
  which 
  the 
  

   more 
  conspicuous 
  plants 
  were 
  already 
  ar- 
  

   ranged 
  by 
  universal 
  consent. 
  Species 
  were 
  dis- 
  

   tinguished 
  by 
  minor 
  marks 
  and 
  often 
  indicated 
  

   by 
  short 
  descriptions, 
  but 
  they 
  were 
  consid- 
  

   ered 
  of 
  secondary 
  importance. 
  

  

  Based 
  on 
  the 
  idea 
  of 
  a 
  direct 
  creation 
  of 
  all 
  

  

  