﻿94 
  Elementary 
  Species 
  

  

  tained 
  from 
  them 
  show 
  that 
  numerous 
  types 
  

   of 
  variability 
  were 
  usually 
  thrown 
  together. 
  

   What 
  type 
  in 
  each 
  case 
  afforded 
  the 
  material, 
  

   which 
  the 
  breeder 
  in 
  reality 
  made 
  use 
  of, 
  has 
  

   only 
  been 
  inquired 
  into 
  in 
  the 
  last 
  few 
  decades. 
  

   Among 
  those 
  who 
  have 
  opened 
  the 
  way 
  for 
  

   thorough 
  and 
  more 
  scientific 
  treatment 
  are 
  to 
  

   be 
  mentioned 
  Eimpau 
  and 
  Von 
  Eiimker 
  of 
  Ger- 
  

   many 
  and 
  W. 
  M. 
  Hays 
  of 
  America. 
  

  

  Von 
  Eiimker 
  is 
  to 
  be 
  considered 
  as 
  the 
  first 
  

   writer, 
  who 
  sharply 
  distinguished 
  between 
  two 
  

   phases 
  of 
  methodical 
  breeding-selection. 
  One 
  

   side 
  he 
  calls 
  the 
  production 
  of 
  new 
  forms, 
  the 
  

   other 
  the 
  improvement 
  of 
  the 
  breed. 
  He 
  dealt 
  

   with 
  both 
  methods 
  extensively. 
  New 
  forms 
  are 
  

   considered 
  as 
  spontaneous 
  variations 
  occurring 
  

   or 
  originating 
  without 
  human 
  aid. 
  They 
  have 
  

   only 
  to 
  be 
  selected 
  and 
  isolated, 
  and 
  their 
  

   progeny 
  at 
  once 
  yields 
  a 
  constant 
  and 
  pure 
  race. 
  

   This 
  race 
  retains 
  its 
  character 
  as 
  long 
  as 
  it 
  is 
  

   protected 
  against 
  the 
  admixture 
  of 
  other 
  minor 
  

   varieties, 
  either 
  by 
  cross-pollination, 
  or 
  by 
  ac- 
  

   cidental 
  seeds. 
  

  

  Improvement, 
  on 
  the 
  other 
  hand, 
  is 
  the 
  work 
  

   of 
  man. 
  New 
  varieties 
  of 
  course 
  can 
  only 
  be 
  

   isolated 
  if 
  chance 
  offers 
  them; 
  the 
  improve- 
  

   ment 
  is 
  not 
  incumbent 
  on 
  chance. 
  It 
  does 
  not 
  

   create 
  really 
  anything 
  new, 
  but 
  develops 
  char- 
  

   acters, 
  which 
  were 
  already 
  existing. 
  It 
  brings 
  

  

  