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  nut 
  has 
  in 
  some 
  instances 
  such 
  evident 
  protu- 
  

   berances 
  on 
  the 
  valves 
  of 
  its 
  fruits, 
  that 
  it 
  may 
  

   seem 
  doubtful 
  whether 
  it 
  is 
  a 
  pure 
  and 
  stable 
  

   variety. 
  

  

  Systematic 
  latency 
  may 
  betray 
  itself 
  in 
  dif- 
  

   ferent 
  ways, 
  either 
  by 
  normal 
  systematic 
  

   marks, 
  or 
  by 
  atavism. 
  With 
  the 
  latter 
  I 
  shall 
  

   deal 
  at 
  length 
  on 
  another 
  occasion, 
  and 
  there- 
  

   fore 
  I 
  will 
  give 
  here 
  only 
  one 
  very 
  clear 
  and 
  

   beautiful 
  example. 
  It 
  is 
  afforded 
  by 
  the 
  com- 
  

   mon 
  red 
  clover. 
  Obviously 
  the 
  clovers, 
  with 
  

   their 
  three 
  leaflets 
  in 
  each 
  leaf, 
  stand 
  in 
  the 
  

   midst 
  of 
  the 
  great 
  family 
  of 
  papilionaceous 
  

   plants,the 
  leaves 
  of 
  which 
  are 
  generally 
  pinnate. 
  

   Systematic 
  affinity 
  suggests 
  that 
  the 
  " 
  three- 
  

   leaved 
  " 
  forms 
  must 
  have 
  been 
  derived 
  from 
  

   pinnate 
  ancestors, 
  evidently 
  by 
  the 
  reduction 
  of 
  

   the 
  number 
  of 
  the 
  leaflets. 
  In 
  some 
  species 
  of 
  

   clover 
  the 
  middle 
  of 
  the 
  three 
  is 
  more 
  or 
  less 
  

   stalked, 
  as 
  is 
  ordinarily 
  the 
  case 
  in 
  pinnate 
  

   leaves; 
  in 
  others 
  it 
  is 
  as 
  sessile 
  as 
  are 
  its 
  neigh- 
  

   bors. 
  In 
  a 
  subsequent 
  chapter 
  I 
  will 
  describe 
  a 
  

   very 
  fine 
  variety, 
  which 
  sometimes 
  occurs 
  in 
  the 
  

   wild 
  state 
  and 
  may 
  easily 
  be 
  isolated 
  and 
  culti- 
  

   vated. 
  It 
  is 
  an 
  ordinary 
  red 
  clover 
  with 
  five 
  

   leaflets 
  instead 
  of 
  three, 
  and 
  with 
  this 
  number 
  

   varying 
  between 
  three 
  and 
  seven, 
  instead 
  of 
  be- 
  

   ing 
  nearly 
  wholly 
  stable 
  as 
  in 
  the 
  common 
  form. 
  

   It 
  produces 
  from 
  time 
  to 
  time 
  pinnate 
  leaves, 
  

  

  