﻿464 
  Mutations 
  

  

  is 
  no 
  real 
  and 
  intimate 
  connection 
  between 
  these 
  

   two 
  great 
  conceptions. 
  Darwin 
  frequently 
  

   pointed 
  out 
  that 
  a 
  long 
  period 
  of 
  time 
  might 
  be 
  

   needed 
  for 
  slow 
  improvements, 
  and 
  was 
  also 
  a 
  

   condition 
  for 
  the 
  occurrence 
  of 
  rare 
  sports. 
  In 
  

   any 
  case 
  those 
  writers 
  have 
  been 
  in 
  error, 
  ac- 
  

   cording 
  to 
  my 
  opinion, 
  who 
  have 
  refrained 
  from 
  

   experimental 
  work 
  on 
  the 
  origin 
  of 
  species, 
  on 
  

   account 
  of 
  this 
  narrow 
  interpretation 
  of 
  Dar- 
  

   win's 
  views. 
  The 
  choice 
  of 
  the 
  material 
  is 
  

   quite 
  another 
  question, 
  and 
  obviously 
  all 
  de- 
  

   pends 
  upon 
  this 
  choice. 
  Promising 
  instances 
  

   must 
  be 
  sought 
  for, 
  but 
  as 
  a 
  rule 
  the 
  best 
  way 
  

   is 
  to 
  test 
  as 
  many 
  plants 
  as 
  possible. 
  Many 
  of 
  

   them 
  may 
  show 
  nothing 
  of 
  interest, 
  but 
  some 
  

   might 
  lead 
  to 
  the 
  desired 
  end. 
  

  

  For 
  to-day's 
  lecture 
  I 
  have 
  chosen 
  an 
  in- 
  

   stance, 
  in 
  which 
  the 
  grounds 
  upon 
  which 
  the 
  

   choice 
  was 
  based 
  are 
  very 
  evident. 
  It 
  is 
  the 
  

   origin 
  of 
  the 
  peloric 
  toad-flax 
  (Linaria 
  vulgaris 
  

   peloria). 
  

  

  The 
  ground 
  for 
  this 
  choice 
  lies 
  simply 
  in 
  the 
  

   fact 
  that 
  the 
  peloric 
  toad-flax 
  is 
  known 
  to 
  have 
  

   originated 
  from 
  the 
  ordinary 
  type 
  at 
  different 
  

   times 
  and 
  in 
  different 
  countries, 
  under 
  more 
  or 
  

   less 
  divergent 
  conditions. 
  It 
  had 
  arisen 
  from 
  

   time 
  to 
  time, 
  and 
  hence 
  I 
  presumed 
  that 
  there 
  

   was 
  a 
  chance 
  to 
  see 
  it 
  arise 
  again. 
  If 
  this 
  

   should 
  happen 
  under 
  experimental 
  circum- 
  

  

  