﻿278 
  Retrograde 
  Varieties 
  

  

  built 
  up 
  of 
  one 
  active 
  and 
  one 
  dormant 
  unit. 
  

  

  Thirdly 
  this 
  deviating 
  pair 
  will 
  exhibit 
  the 
  

   active 
  unit 
  which 
  it 
  contains, 
  and 
  the 
  hybrid 
  

   will 
  show 
  the 
  aspect 
  of 
  the 
  parent 
  in 
  which 
  

   the 
  character 
  was 
  active 
  and 
  not 
  that 
  of 
  the 
  

   parent 
  in 
  which 
  it 
  was 
  dormant. 
  Now 
  the 
  ac- 
  

   tive 
  quality 
  was 
  that 
  of 
  the 
  species, 
  and 
  its 
  

   latent 
  state 
  was 
  found 
  in 
  the 
  variety. 
  Hence 
  

   the 
  inference 
  that 
  hybrids 
  between 
  a 
  species 
  

   and 
  its 
  retrograde 
  variety 
  will 
  bear 
  the 
  aspect 
  

   of 
  the 
  species. 
  This 
  attribute 
  may 
  be 
  fully 
  

   developed, 
  and 
  then 
  the 
  hybrid 
  will 
  not 
  be 
  dis- 
  

   tinguishable 
  from 
  the 
  pure 
  species 
  in 
  its 
  outer 
  

   appearance. 
  Or 
  the 
  character 
  may 
  be 
  incom- 
  

   pletely 
  evolved, 
  owing 
  to 
  the 
  failure 
  of 
  coopera- 
  

   tion 
  of 
  the 
  dormant 
  unit. 
  In 
  this 
  case 
  the 
  hy- 
  

   brid 
  will 
  be 
  in 
  some 
  sense 
  intermediate 
  between 
  

   its 
  parents, 
  but 
  these 
  instances 
  are 
  more 
  rare 
  

   than 
  the 
  alternate 
  ones, 
  though 
  presumably 
  

   they 
  may 
  play 
  an 
  important 
  part 
  in 
  the 
  varia- 
  

   bility 
  of 
  many 
  hybrid 
  garden-flowers. 
  

  

  All 
  of 
  these 
  three 
  rules 
  are 
  supported 
  by 
  a 
  

   large 
  amount 
  of 
  evidence. 
  The 
  complete 
  fertil- 
  

   ity 
  of 
  varietal 
  hybrids 
  is 
  so 
  universally 
  acknowl- 
  

   edged 
  that 
  it 
  is 
  not 
  worth 
  while 
  to 
  give 
  special 
  

   instances. 
  With 
  many 
  prominent 
  systematists 
  

   it 
  has 
  become 
  a 
  test 
  between 
  species 
  and 
  vari- 
  

   eties, 
  and 
  from 
  our 
  present 
  point 
  of 
  view 
  this 
  as- 
  

   sumption 
  is 
  correct. 
  Only 
  the 
  test 
  is 
  of 
  little 
  

   use 
  in 
  practice, 
  as 
  fertility 
  may 
  be 
  diminished 
  

  

  