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  Fluctuations 
  

  

  lief. 
  It 
  further 
  reasons 
  that 
  a 
  direct 
  apprecia- 
  

   tion 
  of 
  the 
  capacity 
  of 
  inheritance 
  can 
  only 
  be 
  

   derived 
  from 
  the 
  observation 
  of 
  the 
  inheritance 
  

   itself. 
  Hence 
  it 
  concludes 
  that 
  the 
  average 
  

   value 
  of 
  the 
  offspring 
  is 
  the 
  only 
  real 
  standard 
  

   by 
  which 
  to 
  judge 
  the 
  representatives 
  of 
  a 
  race 
  

   and 
  to 
  found 
  selection 
  upon. 
  

  

  These 
  statements 
  are 
  so 
  directly 
  opposed 
  to 
  

   views 
  prevalent 
  among 
  plant-breeders, 
  that 
  it 
  

   seems 
  necessary 
  to 
  deal 
  with 
  them 
  from 
  the 
  

   theoretical 
  and 
  experimental, 
  as 
  well 
  as 
  from 
  

   the 
  practical 
  side. 
  

  

  The 
  theoretical 
  arguments 
  rest 
  on 
  the 
  divi- 
  

   sion 
  of 
  the 
  fluctuating 
  variability 
  into 
  the 
  two 
  

   large 
  classes 
  of 
  individual 
  or 
  embryonic, 
  and 
  of 
  

   partial 
  deviations. 
  We 
  have 
  dealt 
  with 
  this 
  di- 
  

   vision 
  at 
  some 
  length 
  in 
  the 
  previous 
  lecture. 
  

   It 
  will 
  be 
  apparent 
  at 
  once, 
  if 
  we 
  choose 
  a 
  defi- 
  

   nite 
  example. 
  Let 
  us 
  ask 
  what 
  is 
  the 
  real 
  sig- 
  

   nificance 
  of 
  the 
  percentage-figure 
  of 
  a 
  single 
  

   plant 
  in 
  sugar-beets. 
  This 
  value 
  depends 
  in 
  

   the 
  first 
  place, 
  on 
  the 
  strain 
  or 
  family 
  from 
  

   which 
  the 
  beet 
  has 
  been 
  derived, 
  but 
  this 
  pri- 
  

   mary 
  point 
  may 
  be 
  neglected 
  here, 
  because 
  it 
  

   is 
  the 
  same 
  for 
  all 
  the 
  beets 
  of 
  any 
  lot, 
  and 
  de- 
  

   termines 
  the 
  average, 
  around 
  which 
  all 
  are 
  fluc- 
  

   tuating. 
  

  

  The 
  deviation 
  of 
  the 
  percentage-figure 
  of 
  a 
  

   single 
  beet 
  depends 
  on 
  two 
  main 
  groups 
  of 
  ex- 
  

  

  