﻿240 
  Retrograde 
  Varieties 
  

  

  age 
  of 
  many 
  other 
  plants 
  behaves 
  likewise, 
  as 
  

   also 
  do 
  apples 
  and 
  peaches 
  on 
  the 
  insolated 
  

   sides 
  of 
  the 
  fruits. 
  It 
  is 
  quite 
  impossible 
  to 
  

   state 
  these 
  groups 
  of 
  facts 
  in 
  a 
  more 
  simple 
  way 
  

   than 
  by 
  the 
  statement 
  that 
  the 
  tendency 
  to 
  be- 
  

   come 
  red 
  is 
  almost 
  generally 
  present, 
  though 
  

   latent 
  in 
  leaves 
  and 
  stems 
  ? 
  and 
  that 
  it 
  comes 
  

   into 
  activity 
  whenever 
  a 
  stimulus 
  provokes 
  it. 
  

  

  Now 
  it 
  must 
  be 
  granted 
  that 
  the 
  energizing 
  

   of 
  such 
  a 
  propensity 
  under 
  ordinary 
  circum- 
  

   stances 
  is 
  quite 
  another 
  thing 
  from 
  the 
  orig- 
  

   ination 
  of 
  a 
  positive 
  variety 
  by 
  the 
  evolution 
  

   of 
  the 
  same 
  character. 
  In 
  the 
  variety 
  the 
  ac- 
  

   tivity 
  has 
  become 
  independent 
  of 
  outer 
  in- 
  

   fluences 
  or 
  dependent 
  upon 
  them 
  in 
  a 
  far 
  lesser 
  

   degree. 
  The 
  power 
  of 
  producing 
  the 
  red 
  pig- 
  

   ments 
  is 
  shown 
  to 
  be 
  latent 
  by 
  the 
  facts 
  given 
  

   above, 
  and 
  we 
  see 
  that 
  in 
  the 
  variety 
  it 
  is 
  no 
  

   longer 
  latent 
  but 
  is 
  in 
  perfect 
  and 
  lasting 
  ac- 
  

   tivity 
  throughout 
  the 
  whole 
  life 
  of 
  the 
  plant. 
  

  

  Red 
  varieties 
  of 
  white 
  flowers 
  are 
  much 
  more 
  

   rare. 
  Here 
  the 
  latency 
  of 
  the 
  red 
  pigment 
  may 
  

   be 
  deduced 
  partly 
  from 
  general 
  arguments 
  like 
  

   those 
  just 
  given, 
  partly 
  from 
  the 
  special 
  syste- 
  

   matic 
  relations 
  in 
  the 
  given 
  cases. 
  Hildebrand 
  

   has 
  clearly 
  worked 
  out 
  this 
  mode 
  of 
  proof. 
  He 
  

   showed 
  by 
  the 
  critical 
  examination 
  of 
  a 
  large 
  

   number 
  of 
  instances 
  that 
  the 
  occurrence 
  of 
  the 
  

   red-flowered 
  varieties 
  is 
  contingent 
  upon 
  the 
  

  

  