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  Fluctuations 
  

  

  remains 
  the 
  same. 
  The 
  result 
  is 
  that 
  many 
  

   thousands 
  of 
  seedlings 
  are 
  required 
  to 
  go 
  be- 
  

   yond 
  the 
  ordinary 
  range 
  of 
  variations, 
  and 
  that 
  

   every 
  further 
  improvement 
  requires 
  the 
  doub- 
  

   ling 
  of 
  the 
  whole 
  culture. 
  If 
  ten 
  thousand 
  do 
  

   not 
  give 
  a 
  profitable 
  deviation, 
  the 
  next 
  step 
  re- 
  

   quires 
  twenty 
  thousand, 
  the 
  following 
  forty 
  

   thousand, 
  and 
  so 
  on. 
  And 
  all 
  this 
  work 
  would 
  

   be 
  necessary 
  for 
  the 
  improvement 
  of 
  a 
  single 
  

   quality, 
  while 
  practice 
  requires 
  the 
  examination 
  

   and 
  amelioration 
  of 
  nearly 
  all 
  the 
  variable 
  

   characters 
  of 
  the 
  strain. 
  

  

  Hence 
  the 
  rule 
  that 
  great 
  results 
  can 
  only 
  be 
  

   obtained 
  by 
  the 
  use 
  of 
  large 
  numbers, 
  but 
  it 
  is 
  

   of 
  no 
  avail 
  to 
  state 
  this 
  conclusion 
  from 
  a 
  scien- 
  

   tific 
  point 
  of 
  view. 
  Scientific 
  experimenters 
  

   will 
  rarely 
  be 
  able 
  to 
  sacrifice 
  fifty 
  thousand 
  

   plants 
  to 
  a 
  single 
  selection. 
  The 
  problem 
  is 
  to 
  

   introduce 
  the 
  principle 
  into 
  practice 
  and 
  to 
  

   prove 
  its 
  direct 
  usefulness 
  and 
  reliability. 
  It 
  is 
  

   to 
  Luther 
  Burbank 
  that 
  we 
  owe 
  this 
  great 
  

   achievement. 
  His 
  principles 
  are 
  in 
  full 
  har- 
  

   mony 
  with 
  the 
  teachings 
  of 
  science. 
  His 
  meth- 
  

   ods 
  are 
  hybridization 
  and 
  selection 
  in 
  the 
  

   broadest 
  sense 
  and 
  on 
  the 
  largest 
  scale. 
  One 
  

   very 
  illustrative 
  example 
  of 
  his 
  methods 
  must 
  

   suffice 
  to 
  convey 
  an 
  idea 
  of 
  the 
  work 
  necessary 
  

   to 
  produce 
  a 
  new 
  race 
  of 
  superlative 
  excel- 
  

   lency. 
  Forty 
  thousand 
  blackberry 
  and 
  rasp- 
  

  

  