﻿LECTURE 
  XXI 
  

  

  MUTATIONS 
  IN 
  HORTICULTURE 
  

  

  It 
  is 
  well 
  known 
  that 
  Darwin 
  based 
  his 
  theory 
  

   of 
  natural 
  selection 
  to 
  a 
  large 
  extent 
  upon 
  the 
  

   experience 
  of 
  breeders. 
  Natural 
  and 
  artificial 
  

   selection 
  exhibit 
  the 
  same 
  general 
  features, 
  yet 
  

   it 
  was 
  impossible 
  in 
  Darwin's 
  time 
  to 
  make 
  a 
  

   critical 
  and 
  comparative 
  analysis 
  of 
  the 
  two 
  

   processes. 
  

  

  In 
  accordance 
  with 
  our 
  present 
  conception 
  

   there 
  is 
  selection 
  of 
  species 
  and 
  selection 
  within 
  

   the 
  species. 
  The 
  struggle 
  for 
  life 
  determines 
  

   which 
  of 
  a 
  group 
  of 
  elementary 
  species 
  shall 
  sur- 
  

   vive 
  and 
  which 
  shall 
  disappear. 
  In 
  agricultural 
  

   practice 
  the 
  corresponding 
  process 
  is 
  usually 
  

   designated 
  by 
  the 
  name 
  of 
  variety-testing. 
  

   Within 
  the 
  species, 
  or 
  within 
  the 
  variety, 
  the 
  

   sieve 
  of 
  natural 
  selection 
  is 
  constantly 
  eliminat- 
  

   ing 
  poor 
  specimens 
  and 
  preserving 
  those 
  that 
  

   are 
  best 
  adapted 
  to 
  live 
  under 
  the 
  given 
  condi- 
  

   tions. 
  Some 
  amelioration 
  and 
  some 
  local 
  races 
  

   are 
  the 
  result, 
  but 
  this 
  does 
  not 
  appear 
  to 
  be 
  of 
  

   much 
  importance. 
  On 
  the 
  contrary, 
  the 
  selec- 
  

  

  604 
  

  

  