﻿xii 
  Preface 
  by 
  the 
  Editor 
  

  

  discussions 
  and 
  demonstrations 
  to 
  a 
  form 
  suitable 
  for 
  

   permanent 
  record, 
  together 
  with 
  certain 
  other 
  alterations 
  

   which 
  have 
  been 
  duly 
  submitted 
  to 
  the 
  author. 
  The 
  

   original 
  phraseology 
  has 
  been 
  preserved 
  as 
  far 
  as 
  pos- 
  

   sible. 
  The 
  editor 
  wishes 
  to 
  acknowledge 
  material 
  as- 
  

   sistance 
  in 
  this 
  work 
  from 
  Miss 
  A. 
  M. 
  Vail, 
  Librarian 
  of 
  

   the 
  New 
  York 
  Botanical 
  Garden. 
  

  

  D. 
  T. 
  MACDOUGAL. 
  

  

  New 
  York 
  Botanical 
  Garden, 
  October, 
  1904- 
  

  

  PREFACE 
  TO 
  THE 
  SECOND 
  EDITION. 
  

  

  THE 
  constantly 
  increasing 
  interest 
  in 
  all 
  phases 
  of 
  evo- 
  

   lution 
  has 
  made 
  necessary 
  the 
  preparation 
  of 
  a 
  second 
  

   edition 
  of 
  this 
  book 
  within 
  a 
  few 
  months 
  after 
  the 
  first 
  

   appeared. 
  The 
  opportunity 
  has 
  been 
  used 
  to 
  eliminate 
  

   typographical 
  errors, 
  and 
  to 
  make 
  alterations 
  in 
  the 
  form 
  

   of 
  a 
  few 
  sentences 
  for 
  the 
  sake 
  of 
  clearness 
  and 
  smooth- 
  

   ness. 
  The 
  subject 
  matter 
  remains 
  practically 
  unchanged. 
  

   An 
  explanatory 
  note 
  has 
  been 
  added 
  on 
  page 
  575 
  in 
  order 
  

   to 
  avoid 
  confusion 
  as 
  to 
  the 
  identity 
  of 
  some 
  of 
  the 
  plants 
  

   which 
  figure 
  prominently 
  in 
  the 
  experimental 
  investiga- 
  

   tions 
  in 
  Amsterdam 
  and 
  New 
  York. 
  

  

  The 
  portrait 
  which 
  forms 
  the 
  frontispiece 
  is 
  a 
  repro- 
  

   duction 
  of 
  a 
  photograph 
  taken 
  by 
  Professor 
  F. 
  E. 
  Lloyd 
  

   and 
  Dr. 
  W. 
  A. 
  Cannon 
  during 
  the 
  visit 
  of 
  Professor 
  de 
  

   Vries 
  at 
  the 
  Desert 
  Botanical 
  Laboratory 
  of 
  the 
  Carnegie 
  

   Institution, 
  at 
  Tucson, 
  Arizona, 
  in 
  June, 
  1904. 
  

  

  D. 
  T. 
  MACDOUGAL. 
  

   December 
  15, 
  1905. 
  

  

  