﻿B. 
  ELEMENTARY 
  SPECIES 
  

  

  t 
  

  

  LECTUKE 
  II 
  

  

  ELEMENTAKY 
  SPECIES 
  IN 
  NATURE 
  

  

  What 
  are 
  species? 
  Species 
  are 
  considered 
  

   as 
  the 
  true 
  units 
  of 
  nature 
  by 
  the 
  vast 
  majority 
  

   of 
  biologists. 
  They 
  have 
  gained 
  this 
  high 
  

   rank 
  in 
  our 
  estimation 
  principally 
  through 
  the 
  

   influence 
  of 
  Linnaeus. 
  They 
  have 
  supplanted 
  

   the 
  genera 
  which 
  were 
  the 
  accepted 
  units 
  before 
  

   Linnaeus. 
  They 
  are 
  now 
  to 
  be 
  replaced 
  in 
  their 
  

   turn, 
  by 
  smaller 
  types, 
  for 
  reasons 
  which 
  do 
  not 
  

   rest 
  upon 
  comparative 
  studies 
  but 
  upon 
  direct 
  

   experimental 
  evidence. 
  

  

  Biological 
  studies 
  and 
  practical 
  interests 
  

   alike 
  make 
  new 
  demands 
  upon 
  systematic 
  bot- 
  

   any. 
  Species 
  are 
  not 
  only 
  the 
  subject-material 
  

   of 
  herbaria 
  and 
  collections, 
  but 
  they 
  are 
  living 
  

   entities, 
  and 
  their 
  life-history 
  and 
  life-condi- 
  

   tions 
  command 
  a 
  gradually 
  increasing 
  interest. 
  

   One 
  phase 
  of 
  the 
  question 
  is 
  to 
  determine 
  the 
  

   easiest 
  manner 
  to 
  deal 
  with 
  the 
  collected 
  forms 
  

   of 
  a 
  country, 
  and 
  another 
  feature 
  is 
  the 
  problem 
  

  

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