﻿PEEFACE 
  BY 
  THE 
  AUTHOR 
  

  

  THE 
  purpose 
  of 
  these 
  lectures 
  is 
  to 
  point 
  out 
  the 
  means 
  

   and 
  methods 
  by 
  which 
  the 
  origin 
  of 
  species 
  and 
  varieties 
  

   may 
  become 
  an 
  object 
  for 
  experimental 
  inquiry, 
  in 
  the 
  

   interest 
  of 
  agricultural 
  and 
  horticultural 
  practice 
  as 
  well 
  

   as 
  in 
  that 
  of 
  general 
  biologic 
  science. 
  Comparative 
  

   studies 
  have 
  contributed 
  all 
  the 
  evidence 
  hitherto 
  adduced 
  

   for 
  the 
  support 
  of 
  the 
  Darwinian 
  theory 
  of 
  descent 
  and 
  

   given 
  us 
  some 
  general 
  ideas 
  about 
  the 
  main 
  lines 
  of 
  the 
  

   pedigree 
  of 
  the 
  vegetable 
  kingdom, 
  but 
  the 
  way 
  in 
  which 
  

   one 
  species 
  originates 
  from 
  another 
  has 
  not 
  been 
  ade- 
  

   quately 
  explained. 
  The 
  current 
  belief 
  assumes 
  that 
  spe- 
  

   cies 
  are 
  slowly 
  changed 
  into 
  new 
  types. 
  In 
  contradiction 
  

   to 
  this 
  conception 
  the 
  theory 
  of 
  mutation 
  assumes 
  that 
  

   new 
  species 
  and 
  varieties 
  are 
  produced 
  from 
  existing 
  

   forms 
  by 
  sudden 
  leaps. 
  The 
  parent-type 
  itself 
  remains 
  

   unchanged 
  throughout 
  this 
  process, 
  and 
  may 
  repeatedly 
  

   give 
  birth 
  to 
  new 
  forms. 
  These 
  may 
  arise 
  simultaneously 
  

   and 
  in 
  groups 
  or 
  separately 
  at 
  more 
  or 
  less 
  widely 
  dis- 
  

   tant 
  periods. 
  

  

  The 
  principal 
  features 
  of 
  the 
  theory 
  of 
  mutation 
  have 
  

   been 
  dealt 
  with 
  at 
  length 
  in 
  my 
  book 
  " 
  Die 
  Mutations- 
  

   theorie" 
  (Vol. 
  I., 
  1901, 
  Vol. 
  II., 
  1903. 
  Leipsic, 
  Veit 
  

   & 
  Co.), 
  in 
  which 
  I 
  have 
  endeavored 
  to 
  present 
  as 
  com- 
  

   pletely 
  as 
  possible 
  the 
  detailed 
  evidence 
  obtained 
  from 
  

   trustworthy 
  historical 
  records, 
  and 
  from 
  my 
  own 
  experi- 
  

   mental 
  researches, 
  upon 
  which 
  the 
  theory 
  is 
  based. 
  

  

  The 
  University 
  of 
  California 
  invited 
  me 
  to 
  deliver 
  a 
  

   series 
  of 
  lectures 
  on 
  this 
  subject, 
  at 
  Berkeley, 
  during 
  the 
  

  

  

  

  VII 
  

  

  