﻿Inconstancy 
  of 
  Improved 
  Races 
  783 
  

  

  of 
  them 
  has 
  been 
  counted 
  and 
  the 
  figures 
  com- 
  

   bined 
  into 
  curves, 
  which 
  at 
  once 
  show 
  the 
  whole 
  

   course 
  of 
  the 
  pedigree-experiment. 
  These 
  

   curves 
  have 
  in 
  the 
  main 
  taken 
  the 
  same 
  shape, 
  

   and 
  have 
  only 
  gradually 
  been 
  moved 
  in 
  the 
  

   chosen 
  direction. 
  

  

  Three 
  points 
  are 
  now 
  to 
  be 
  considered 
  in 
  

   connection 
  with 
  this 
  experiment. 
  The 
  first 
  is 
  

   the 
  size 
  of 
  the 
  cultures 
  required 
  for 
  the 
  result- 
  

   ing 
  amelioration. 
  In 
  other 
  words, 
  would 
  it 
  have 
  

   been 
  possible 
  to 
  attain 
  an 
  average 
  of 
  20 
  rows 
  

   in 
  a 
  single 
  experiment? 
  This 
  is 
  a 
  matter 
  of 
  cal- 
  

   culation, 
  and 
  the 
  calculation 
  must 
  be 
  based 
  upon 
  

   the 
  experience 
  related 
  above, 
  that 
  the 
  progres- 
  

   sion 
  in 
  the 
  case 
  of 
  maize 
  is 
  equal 
  to 
  two-fifths 
  of 
  

   the 
  parental 
  deviation. 
  A 
  cob 
  with 
  20 
  rows 
  

   means 
  a 
  deviation 
  of 
  7 
  from 
  the 
  average 
  of 
  13, 
  

   the 
  incipient 
  value 
  of 
  my 
  race. 
  To 
  reach 
  such 
  

   an 
  average 
  at 
  once, 
  an 
  ear 
  would 
  be 
  required 
  

   with 
  7x 
  5 
  / 
  2 
  17% 
  rows 
  above 
  the 
  average, 
  or 
  

   an 
  ear 
  with 
  30 
  - 
  32 
  rows. 
  These 
  never 
  occur, 
  

   but 
  the 
  rule 
  given 
  in 
  a 
  previous 
  lecture 
  gives 
  a 
  

   method 
  of 
  calculating 
  the 
  probability 
  of 
  their 
  

   occurrence, 
  or 
  in 
  other 
  words, 
  the 
  number 
  of 
  

   ears 
  required 
  to 
  give 
  a 
  chance 
  of 
  finding 
  such 
  

   an 
  ear. 
  It 
  would 
  take 
  too 
  long 
  to 
  give 
  this 
  cal- 
  

   culation 
  here, 
  but 
  I 
  find 
  that 
  approximately 
  12,- 
  

   000 
  ears 
  would 
  be 
  required 
  to 
  give 
  one 
  with 
  28 
  

   rows, 
  which 
  was 
  the 
  highest 
  number 
  attained 
  in 
  

  

  