﻿296 
  Retrograde 
  Varieties 
  

  

  ity 
  and 
  the 
  other 
  half 
  ovules 
  with 
  the 
  opposite 
  

   character. 
  

  

  Calling 
  P 
  pollen 
  and 
  ovules, 
  and 
  represent- 
  

   ing 
  the 
  active 
  mark 
  by 
  P 
  and 
  0, 
  the 
  latent 
  qual- 
  

   ities 
  by 
  P' 
  and 
  0', 
  they 
  would 
  combine 
  as 
  fol- 
  

   lows: 
  

  

  P+0 
  giving 
  uniform 
  pairs 
  with 
  the 
  active 
  mark, 
  

  

  P 
  + 
  O' 
  giving 
  unequal 
  pairs, 
  

  

  P' 
  + 
  O 
  giving 
  unequal 
  pairs, 
  

  

  P' 
  + 
  O' 
  giving 
  uniform 
  pairs 
  with 
  the 
  latent 
  mark. 
  

  

  In 
  this 
  combination 
  the 
  four 
  groups 
  are 
  ob- 
  

   viously 
  of 
  the 
  same 
  size, 
  each 
  containing 
  one- 
  

   fourth 
  of 
  the 
  offspring. 
  Manifestly 
  they 
  corre- 
  

   spond 
  exactly 
  to 
  the 
  direct 
  results 
  of 
  the 
  

   experiments, 
  P 
  + 
  representing 
  the 
  indi- 
  

   viduals 
  which 
  reverted 
  to 
  the 
  specific 
  mark, 
  

   P'+O' 
  those 
  who 
  reassumed 
  the 
  varietal 
  

   quality 
  and 
  P+0' 
  and 
  P+0' 
  those 
  who 
  hybrid- 
  

   ized 
  for 
  the 
  second 
  time. 
  These 
  considerations 
  

   lead 
  us 
  to 
  the 
  following 
  form 
  of 
  Mendel's 
  

   formula 
  : 
  

  

  P 
  + 
  O 
  = 
  l/4-Active 
  or 
  1 
  A, 
  

  

  P+0') 
  

  

  p/ 
  _j_ 
  Q 
  j 
  = 
  1/2-Hybrid 
  or 
  2 
  H, 
  

  

  P' 
  + 
  O' 
  =l/4-Latent 
  or 
  1 
  L, 
  

  

  Which 
  is 
  evidently 
  the 
  same 
  as 
  Mendel's 
  

   empirical 
  law 
  given 
  above. 
  

  

  To 
  give 
  the 
  proof 
  of 
  these 
  assumptions 
  Men- 
  

   del 
  has 
  devised 
  a 
  very 
  simple 
  crossing 
  experi- 
  

  

  