﻿284 
  Retrograde 
  Varieties 
  

  

  brid 
  with 
  the 
  purple 
  veins 
  and 
  center 
  in 
  the 
  

   corolla 
  of 
  the 
  former, 
  the 
  white 
  and 
  blue 
  thorn- 
  

   apple 
  produce 
  a 
  blue 
  hybrid, 
  and 
  so 
  on. 
  In- 
  

   stances 
  of 
  this 
  sort 
  are 
  common 
  in 
  cultivated 
  

   plants. 
  

  

  Having 
  given 
  this 
  long 
  list 
  of 
  examples 
  of 
  the 
  

   rule 
  of 
  the 
  dominancy 
  of 
  the 
  active 
  character 
  

   over 
  the 
  opposite 
  dormant 
  unit, 
  the 
  question 
  

   naturally 
  arises 
  as 
  to 
  how 
  the 
  antagonistic 
  

   units 
  are 
  combined 
  in 
  the 
  hybrid. 
  This 
  ques- 
  

   tion 
  is 
  of 
  paramount 
  importance 
  in 
  the 
  consid- 
  

   eration 
  of 
  the 
  offspring 
  of 
  the 
  hybrids. 
  But 
  

   before 
  taking 
  it 
  up 
  it 
  is 
  as 
  well 
  to 
  learn 
  the 
  real 
  

   signification 
  of 
  recessiveness 
  in 
  the 
  hybrids 
  

   themselves. 
  

  

  Recessive 
  characters 
  are 
  shown 
  by 
  those 
  rare 
  

   cases, 
  in 
  which 
  hybrids 
  revert 
  to 
  the 
  varietal 
  

   parent 
  in 
  the 
  vegetative 
  way. 
  In 
  other 
  words 
  

   by 
  bud-variations 
  or 
  sports, 
  analogous 
  to 
  the 
  

   splitting 
  of 
  Adam's 
  laburnum 
  into 
  its 
  parents, 
  

   by 
  means 
  of 
  bud-variation 
  already 
  described. 
  

   But 
  here 
  the 
  wide 
  range 
  of 
  differentiating 
  char- 
  

   acters 
  of 
  the 
  parents 
  of 
  this 
  most 
  curious 
  hybrid 
  

   fail. 
  The 
  illustrative 
  examples 
  are 
  extremely 
  

   simple, 
  and 
  are 
  limited 
  to 
  the 
  active 
  and 
  inactive 
  

   condition 
  of 
  only 
  one 
  quality. 
  

  

  An 
  instance 
  is 
  given 
  by 
  the 
  long-leaved 
  vero- 
  

   nica 
  (Veronica 
  longifolia), 
  which 
  has 
  bluish 
  

   flowers 
  in 
  long 
  spikes. 
  The 
  hybrid 
  between 
  

  

  