﻿Theories 
  of 
  Evolution 
  11 
  

  

  double 
  meaning. 
  One 
  is 
  the 
  systematic 
  species, 
  

   which 
  is 
  the 
  unit 
  of 
  our 
  system. 
  But 
  these 
  

   units 
  are 
  by 
  no 
  means 
  indivisible. 
  Long 
  ago 
  

   Linnaeus 
  knew 
  them 
  to 
  be 
  compound 
  in 
  a 
  great 
  

   number 
  of 
  instances, 
  and 
  increasing 
  knowledge 
  

   has 
  shown 
  that 
  the 
  same 
  rule 
  prevails 
  in 
  other 
  

   instances. 
  Today 
  the 
  vast 
  majority 
  of 
  the 
  old 
  

   systematic 
  species 
  are 
  known 
  to 
  consist 
  of 
  minor 
  

   units. 
  These 
  minor 
  entities 
  are 
  called 
  varieties 
  

   in 
  systematic 
  works. 
  However, 
  there 
  are 
  many 
  

   objections 
  to 
  this 
  usage. 
  First, 
  the 
  term 
  vari- 
  

   ety 
  is 
  applied 
  in 
  horticulture 
  and 
  agriculture 
  

   to 
  things 
  so 
  widely 
  divergent 
  as 
  to 
  convey 
  no 
  

   clear 
  idea 
  at 
  all. 
  Secondly, 
  the 
  subdivisions 
  

   of 
  species 
  are 
  by 
  no 
  means 
  all 
  of 
  the 
  same 
  

   nature, 
  and 
  the 
  systematic 
  varieties 
  include 
  

   units 
  the 
  real 
  value 
  of 
  which 
  is 
  widely 
  differ- 
  

   ent 
  in 
  different 
  cases. 
  Some 
  of 
  these 
  vari- 
  

   eties 
  are 
  in 
  reality 
  as 
  good 
  as 
  species, 
  and 
  

   have 
  been 
  ' 
  ' 
  elevated, 
  ' 
  as 
  it 
  is 
  called, 
  by 
  some 
  

   writers, 
  to 
  this 
  rank. 
  This 
  conception 
  of 
  the 
  

   elementary 
  species 
  would 
  be 
  quite 
  justifiable, 
  

   and 
  would 
  at 
  once 
  get 
  rid 
  of 
  all 
  difficulties, 
  were 
  

   it 
  not 
  for 
  one 
  practical 
  obstacle. 
  The 
  number 
  

   of 
  the 
  species 
  in 
  all 
  genera 
  would 
  be 
  doubled 
  

   and 
  tripled, 
  and 
  as 
  these 
  numbers 
  are 
  already 
  

   cumbersome 
  in 
  many 
  cases, 
  the 
  distinction 
  of 
  

   the 
  native 
  species 
  of 
  any 
  given 
  country 
  would 
  

   lose 
  most 
  of 
  its 
  charm 
  and 
  interest. 
  

  

  