﻿Experimental 
  Pedigree-Cultures 
  557 
  

  

  my 
  experiment. 
  Obviously 
  they 
  apply 
  not 
  only 
  

   to 
  our 
  evening-primroses, 
  but 
  may 
  be 
  expected 
  

   to 
  be 
  of 
  general 
  validity. 
  This 
  is 
  at 
  once 
  

   manifest, 
  if 
  we 
  compare 
  the 
  group 
  of 
  new 
  mu- 
  

   tants 
  with 
  the 
  swarms 
  of 
  elementary 
  forms 
  

   which 
  compose 
  some 
  of 
  the 
  youngest 
  systematic 
  

   species, 
  and 
  which, 
  as 
  we 
  have 
  seen 
  before, 
  are 
  

   to 
  be 
  considered 
  as 
  the 
  results 
  of 
  previous 
  mu- 
  

   tations. 
  The 
  difference 
  lies 
  in 
  the 
  fact 
  that 
  the 
  

   evening-primroses 
  have 
  been 
  seen 
  to 
  spring 
  

   from 
  their 
  ancestors 
  and 
  that 
  the 
  drabas 
  

   have 
  not. 
  Hence 
  the 
  conclusion 
  that 
  in 
  com- 
  

   paring 
  the 
  two 
  we 
  must 
  leave 
  out 
  the 
  pedigree 
  of 
  

   the 
  evening-primroses 
  and 
  consider 
  only 
  the 
  

   group 
  of 
  forms 
  as 
  they 
  finally 
  show 
  themselves. 
  

   If 
  in 
  doing 
  so 
  we 
  find 
  sufficient 
  similarity, 
  we 
  are 
  

   justified 
  in 
  the 
  conclusion 
  that 
  the 
  drabas 
  and 
  

   others 
  have 
  probably 
  originated 
  in 
  the 
  same 
  way 
  

   as 
  the 
  evening-primroses. 
  Minor 
  points 
  of 
  

   course 
  will 
  differ, 
  but 
  the 
  main 
  lines 
  cannot 
  have 
  

   complied 
  with 
  wholly 
  different 
  laws. 
  All 
  so- 
  

   called 
  swarms 
  of 
  elementary 
  species 
  obviously 
  

   pertain 
  to 
  a 
  single 
  type, 
  and 
  this 
  type 
  includes 
  

   our 
  evening-primroses 
  as 
  the 
  only 
  controlled 
  

   case. 
  

  

  Formulating 
  the 
  laws 
  of 
  mutability 
  for 
  the 
  

   evening-primroses 
  we 
  therefore 
  assume 
  that 
  

   they 
  hold 
  good 
  for 
  numerous 
  other 
  correspond- 
  

   ing 
  cases. 
  

  

  