﻿16 
  Descent 
  

  

  nature 
  and 
  in 
  culture, 
  leaving 
  tlie 
  question 
  of 
  

   their 
  origin 
  to 
  a 
  subsequent 
  experimental 
  treat- 
  

   ment. 
  

  

  The 
  question 
  of 
  the 
  experimental 
  origin 
  of 
  

   new 
  species 
  and 
  varieties 
  has 
  to 
  he 
  taken 
  up 
  

   from 
  two 
  widely 
  separated 
  starting 
  points. 
  This 
  

   may 
  be 
  inferred 
  from 
  what 
  we 
  have 
  already 
  

   seen 
  concerning 
  the 
  two 
  opposing 
  theories, 
  de- 
  

   rived 
  and 
  isolated 
  from 
  Darwin's 
  original 
  

   broad 
  conception. 
  One 
  of 
  them 
  considers 
  

   mutations 
  as 
  the 
  origin 
  of 
  new 
  forms, 
  while 
  the 
  

   other 
  assumes 
  fluctuations 
  to 
  be 
  the 
  source 
  of 
  

   all 
  evolution. 
  

  

  As 
  mentioned 
  above, 
  my 
  own 
  experience 
  has 
  

   led 
  me 
  to 
  accept 
  the 
  first 
  view. 
  Therefore 
  I 
  

   shall 
  have 
  to 
  show 
  that 
  mutations 
  do 
  yield 
  new 
  

   and 
  constant 
  forms, 
  while 
  fluctuations 
  are 
  not 
  

   adequate 
  to 
  do 
  so. 
  Retrograde 
  varieties 
  and 
  

   elementary 
  species 
  may 
  both 
  be 
  seen 
  to 
  be 
  

   produced 
  by 
  sudden 
  mutations. 
  Varieties 
  have 
  

   often 
  been 
  observed 
  to 
  appear 
  at 
  once 
  and 
  quite 
  

   unexpectedly 
  in 
  horticulture 
  and 
  agriculture, 
  

   and 
  a 
  survey 
  of 
  these 
  historical 
  facts 
  will 
  be 
  the 
  

   subject 
  of 
  one 
  of 
  my 
  lectures. 
  In 
  some 
  in- 
  

   stances 
  I 
  have 
  succeeded 
  in 
  repeating 
  these 
  

   observations 
  in 
  my 
  garden 
  under 
  the 
  strict 
  con- 
  

   ditions 
  of 
  a 
  scientific 
  experiment, 
  and 
  these 
  in- 
  

   stances 
  teach 
  us 
  the 
  real 
  nature 
  of 
  the 
  process 
  

   of 
  mutation 
  in 
  all 
  its 
  visible 
  features. 
  New 
  ele- 
  

  

  