﻿Origin 
  of 
  Peloric 
  Toadflax 
  463 
  

  

  are 
  valuable 
  for 
  the 
  elucidation 
  of 
  general 
  prob- 
  

   lems 
  and 
  broad 
  features 
  of 
  the 
  whole 
  pedigree, 
  

   but 
  the 
  narrower 
  and 
  more 
  practical 
  question 
  as 
  

   to 
  the 
  genetic 
  relation 
  of 
  the 
  single 
  forms 
  to 
  one 
  

   another 
  must 
  be 
  studied 
  in 
  another 
  way, 
  by 
  

   direct 
  experiment. 
  The 
  exact 
  methods 
  of 
  the 
  

   laboratory 
  must 
  be 
  used, 
  and 
  in 
  this 
  case 
  the 
  

   garden 
  is 
  the 
  laboratory. 
  The 
  cultures 
  must 
  

   be 
  guarded 
  with 
  the 
  strictest 
  care 
  and 
  every 
  

   precaution 
  taken 
  to 
  exclude 
  opportunities 
  for 
  

   error. 
  The 
  parents 
  and 
  grandparents 
  and 
  their 
  

   offspring 
  must 
  be 
  kept 
  pure 
  and 
  under 
  control, 
  

   and 
  all 
  facts 
  bearing 
  upon 
  the 
  birth 
  or 
  origin 
  of 
  

   the 
  new 
  types 
  should 
  be 
  carefully 
  recorded. 
  

  

  Two 
  great 
  difficulties 
  have 
  of 
  late 
  stood 
  in 
  

   the 
  way 
  of 
  such 
  experimental 
  investigation. 
  

   One 
  of 
  them 
  is 
  of 
  a 
  theoretical, 
  the 
  other 
  of 
  a 
  

   practical 
  nature. 
  One 
  is 
  the 
  general 
  belief 
  in 
  

   the 
  supposed 
  slowness 
  of 
  the 
  process, 
  the 
  other 
  

   is 
  the 
  choice 
  of 
  adequate 
  material 
  for 
  experi- 
  

   mental 
  purposes. 
  Darwin's 
  hypothesis 
  of 
  nat- 
  

   ural 
  selection 
  as 
  the 
  means 
  by 
  which 
  new 
  types 
  

   arise, 
  is 
  now 
  being 
  generally 
  interpreted 
  as 
  

   stating 
  the 
  slow 
  transformation 
  of 
  ordinary 
  

   fluctuating 
  divergencies 
  from 
  the 
  average 
  type 
  

   into 
  specific 
  differences. 
  But 
  in 
  doing 
  so 
  it 
  is 
  

   overlooked 
  that 
  Quetelet's 
  law 
  of 
  fluctuating 
  

   variability 
  was 
  not 
  yet 
  discovered 
  at 
  the 
  time, 
  

   when 
  Darwin 
  propounded 
  his 
  theory. 
  So 
  there 
  

  

  