﻿212 
  Retrograde 
  Varieties 
  

  

  cies 
  will 
  continue 
  during 
  a 
  number 
  of 
  years, 
  

   and 
  it 
  may 
  not 
  be 
  possible 
  to 
  get 
  rid 
  of 
  them 
  

   at 
  all. 
  

  

  It 
  is 
  an 
  often 
  recurring 
  assertion 
  that 
  white 
  

   varieties 
  of 
  colored 
  species 
  are 
  the 
  most 
  stable 
  

   of 
  all 
  horticultural 
  races. 
  They 
  are 
  often 
  said 
  

   to 
  be 
  at 
  least 
  as 
  constant 
  as 
  the 
  species 
  itself, 
  

   and 
  even 
  to 
  surpass 
  it 
  in 
  this 
  quality. 
  With 
  our 
  

   present 
  state 
  of 
  knowledge, 
  the 
  explanation 
  of 
  

   this 
  general 
  experience 
  is 
  easily 
  given. 
  For 
  se- 
  

   lection 
  removes 
  the 
  effect 
  of 
  spontaneous 
  cross- 
  

   es 
  from 
  the 
  variety 
  in 
  each 
  year, 
  and 
  renders 
  it 
  

   practically 
  pure, 
  while 
  it 
  is 
  wholly 
  inadequate 
  

   to 
  produce 
  the 
  same 
  effects 
  on 
  the 
  species, 
  be- 
  

   cause 
  of 
  the 
  concealed 
  hybrids. 
  

  

  The 
  explanation 
  given 
  in 
  this 
  simple 
  instance 
  

   may 
  be 
  applied 
  to 
  the 
  case 
  of 
  different 
  varieties 
  

   of 
  the 
  same 
  species, 
  when 
  growing 
  together 
  

   and 
  crossed 
  naturally 
  by 
  insects. 
  

  

  It 
  would 
  take 
  too 
  long 
  to 
  go 
  into 
  all 
  the 
  de- 
  

   tails 
  that 
  present 
  themselves 
  here 
  to 
  the 
  stu- 
  

   dent 
  of 
  nature 
  and 
  of 
  gardens. 
  I 
  will 
  

   only 
  state, 
  that 
  since 
  varieties 
  differ 
  princi- 
  

   pally 
  from 
  their 
  species 
  by 
  the 
  lack 
  of 
  some 
  

   sharp 
  character, 
  one 
  variety 
  may 
  be 
  character- 
  

   ized 
  by 
  the 
  lack 
  of 
  color 
  of 
  the 
  flowers, 
  another 
  

   by 
  the 
  lack 
  of 
  pubescence, 
  a 
  third 
  by 
  being 
  

   dwarfed, 
  and 
  so 
  on. 
  Every 
  character 
  must 
  be 
  

   studied 
  separately 
  in 
  its 
  effects 
  on 
  the 
  offspring 
  

  

  