﻿False 
  Atavism 
  197 
  

  

  as 
  to 
  prevent 
  cross-pollination 
  by 
  the 
  visits 
  of 
  

   bees. 
  

  

  This 
  purification 
  must 
  be 
  done 
  in 
  nearly 
  every 
  

   generation. 
  . 
  The 
  oldest 
  varieties 
  are 
  to 
  be 
  sub- 
  

   jected 
  to 
  it 
  as 
  well 
  as 
  the 
  latest. 
  There 
  is 
  no 
  

   regular 
  amelioration, 
  no 
  slow 
  progression 
  in 
  the 
  

   direction 
  of 
  becoming 
  free 
  from 
  these 
  admix- 
  

   tures. 
  Continuous 
  selection 
  is 
  indispensable 
  to 
  

   maintain 
  the 
  races 
  in 
  the 
  degree 
  of 
  purity 
  which 
  

   is 
  required 
  in 
  commerce, 
  but 
  it 
  does 
  not 
  lead 
  to 
  

   any 
  improvement. 
  Nor 
  does 
  it 
  go 
  so 
  far 
  as 
  to 
  

   become 
  unnecessary 
  in 
  the 
  future. 
  This 
  shows 
  

   that 
  there 
  must 
  be 
  a 
  continuous 
  source 
  of 
  im- 
  

   purities, 
  which 
  in 
  itself 
  is 
  not 
  neutralized 
  by 
  

   selection, 
  but 
  of 
  which 
  selection 
  can 
  only 
  elim- 
  

   inate 
  the 
  deteriorating 
  elements. 
  

  

  The 
  same 
  selection 
  is 
  usually 
  applied 
  to 
  new 
  

   varieties, 
  when 
  they 
  occasionally 
  arise. 
  In 
  this 
  

   case 
  it 
  is 
  called 
  " 
  fixing," 
  as 
  gardeners 
  gener- 
  

   ally 
  believe 
  that 
  through 
  selection 
  the 
  varieties 
  

   are 
  brought 
  to 
  the 
  required 
  degree 
  of 
  purity. 
  

   This 
  belief 
  seems 
  to 
  rest 
  mainly 
  on 
  obser- 
  

   vations 
  made 
  in 
  practice, 
  where, 
  as 
  we 
  have 
  seen, 
  

   isolation 
  is 
  of 
  very 
  rare 
  application. 
  Most 
  va- 
  

   rieties 
  would 
  no 
  doubt 
  be 
  absolutely 
  pure 
  from 
  

   the 
  first 
  moment 
  of 
  their 
  existence, 
  if 
  it 
  were 
  

   only 
  possible 
  to 
  have 
  them 
  purely 
  fertilized. 
  

   But 
  in 
  practice 
  this 
  is 
  seldom 
  to 
  be 
  obtained. 
  

   Ordinarily 
  the 
  breeder 
  is 
  content 
  with 
  such 
  slow 
  

  

  