﻿202 
  Retrograde 
  Varieties 
  

  

  quite 
  the 
  same 
  way, 
  and 
  since 
  it 
  is 
  obviously 
  

   impossible 
  to 
  attribute 
  them 
  to 
  an 
  innate 
  ten- 
  

   dency 
  to 
  reversion, 
  they 
  afford 
  an 
  absolutely 
  

   irrefutable 
  proof 
  of 
  the 
  assertion 
  that 
  pollen 
  

   is 
  often 
  brought 
  by 
  insects 
  from 
  one 
  lot 
  of 
  

   plants 
  to 
  another. 
  In 
  this 
  way 
  I 
  obtained 
  a 
  

   hybrid 
  between 
  the 
  common 
  Jacob's 
  ladder 
  and 
  

   the 
  allied 
  species 
  Polemonium 
  dissectum. 
  With 
  

   a 
  distance 
  of 
  100 
  meters 
  between 
  them 
  I 
  had 
  

   two 
  hybrid 
  seeds 
  among 
  a 
  hundred 
  of 
  pure 
  

   ones. 
  At 
  a 
  similar 
  distance 
  pollen 
  was 
  carried 
  

   over 
  from 
  the 
  wild 
  radish, 
  Raphanus 
  Raphanis- 
  

   trum, 
  to 
  the 
  allied 
  Raphanus 
  caudatus, 
  and 
  I 
  

   observed 
  the 
  following 
  year 
  some 
  very 
  nice 
  hy- 
  

   brids 
  among 
  my 
  seedlings. 
  A 
  hybrid-bean 
  be- 
  

   tween 
  Phaseolus 
  nanus 
  and 
  P. 
  multiflorus, 
  and 
  

   some 
  hybrids 
  between 
  the 
  yellow 
  daisy, 
  

   Chrysanthemum 
  segetum 
  and 
  the 
  allied 
  Chrys- 
  

   anthemum 
  coronarium 
  or 
  ox-eve 
  daisv 
  which 
  

  

  / 
  / 
  

  

  also 
  arose 
  spontaneously 
  in 
  my 
  garden 
  between 
  

   parents 
  cultivated 
  at 
  recorded 
  distances, 
  might 
  

   further 
  be 
  noted. 
  Further 
  details 
  of 
  these 
  ex- 
  

   periments 
  need 
  not 
  be 
  given. 
  Suffice 
  to 
  say, 
  

   that 
  occasional 
  crosses 
  between 
  species 
  do 
  

   occur, 
  and 
  not 
  even 
  rarely, 
  that 
  thev 
  are 
  easilv 
  

  

  / 
  . 
  % 
  / 
  

  

  recognized 
  as 
  such 
  and 
  cannot 
  be 
  confused 
  with 
  

   cases 
  of 
  atavism, 
  and 
  that 
  therefore 
  they 
  give 
  

   proof 
  to 
  the 
  assumption 
  that 
  in 
  the 
  same 
  way 
  

   crosses 
  ordinarily 
  occur 
  also 
  between 
  varieties 
  

  

  