﻿824 
  Fluctuations 
  

  

  and 
  much 
  more 
  reliable 
  determination 
  can 
  be 
  

   made 
  than 
  on 
  the 
  ground 
  of 
  the 
  minutest 
  exam- 
  

   ination 
  of 
  one 
  single 
  plant. 
  From 
  this 
  point 
  of 
  

   view 
  the 
  method 
  of 
  Hays 
  commands 
  attention. 
  

   But 
  the 
  chief 
  advantage 
  lies 
  in 
  the 
  fact 
  that 
  it 
  is 
  

   a 
  direct 
  proof 
  of 
  that 
  which 
  it 
  is 
  desired 
  to 
  

   prove, 
  while 
  the 
  visible 
  marks 
  give 
  only 
  very 
  in- 
  

   direct 
  information. 
  

  

  Thus 
  the 
  results 
  of 
  the 
  men 
  of 
  practice 
  are 
  in 
  

   full 
  accordance 
  with 
  those 
  of 
  theory 
  and 
  scien- 
  

   tific 
  experiment, 
  and 
  there 
  can 
  be 
  little 
  doubt 
  

   that 
  they 
  open 
  the 
  way 
  for 
  a 
  rapid 
  and 
  impor- 
  

   tant 
  improvement. 
  Once 
  attained, 
  progress 
  

   however, 
  will 
  be 
  dependent 
  on 
  the 
  selection- 
  

   principle, 
  and 
  the 
  hereditary 
  percentage, 
  or 
  

   centgener 
  power 
  or 
  breeding-ability, 
  must 
  be 
  de- 
  

   termined 
  in 
  each 
  generation 
  anew. 
  Without 
  

   this 
  the 
  race 
  would 
  soon 
  regress 
  to 
  its 
  former 
  

   condition. 
  

  

  To 
  return 
  to 
  our 
  starting 
  point, 
  the 
  compari- 
  

   son 
  of 
  artificial 
  and 
  natural 
  selection. 
  Here 
  we 
  

   are 
  at 
  once 
  struck 
  by 
  the 
  fact 
  that 
  it 
  is 
  hardly 
  

   imaginable, 
  how 
  nature 
  can 
  make 
  use 
  of 
  this 
  

   principle. 
  In 
  some 
  measure 
  the 
  members 
  of 
  the 
  

   best 
  centgener 
  will 
  manifestly 
  be 
  at 
  an 
  advan- 
  

   tage, 
  because 
  they 
  contain 
  more 
  fit 
  specimens 
  

   than 
  the 
  other 
  groups. 
  But 
  the 
  struggle 
  for 
  

   existence 
  goes 
  on 
  between 
  individuals, 
  and 
  not 
  

   between 
  groups 
  of 
  brethren 
  against 
  groups 
  of 
  

  

  