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  INTRODUCTION 
  TO 
  BOTANY 
  

  

  ovary 
  wall 
  ripens 
  as 
  a 
  close-fitting, 
  thin 
  coat 
  about 
  the 
  seed, 
  

   and 
  the 
  kind 
  of 
  fruit 
  thus 
  formed 
  is 
  called 
  the 
  akfin: 
  In 
  the 
  

   stony 
  fruits, 
  as 
  in 
  the 
  peach 
  and 
  apricot, 
  the 
  ovary 
  wall 
  divides; 
  

   the 
  inner 
  part 
  produces 
  the 
  hard 
  covering 
  about 
  the 
  seed, 
  and 
  

   the 
  outer 
  part 
  produces 
  the 
  pulpy 
  flesh. 
  In 
  the 
  apple 
  the 
  calyx 
  

   is 
  joined 
  to 
  the 
  wall 
  of 
  the 
  ovary, 
  the 
  seeds 
  are 
  inclosed 
  in 
  the 
  

   ovary 
  cavities, 
  the 
  ovary 
  wall 
  ripens, 
  thus 
  becoming 
  the 
  core 
  

   of 
  the 
  apple, 
  and 
  the 
  calyx 
  ripens 
  into 
  the 
  greater 
  part 
  of 
  the 
  

   fruit. 
  A 
  transverse 
  or 
  a 
  longitudinal 
  section 
  of 
  an 
  apple 
  or 
  pear 
  

   will 
  usually 
  enable 
  one 
  to 
  determine 
  what 
  part 
  of 
  the 
  fruit 
  is 
  

   the 
  ripened 
  calyx 
  and 
  what 
  part 
  is 
  the 
  ovary 
  wall. 
  

  

  In 
  some 
  cases 
  whole 
  clusters 
  of 
  flowers 
  and 
  the 
  modified 
  

   portions 
  of 
  the 
  stem 
  upon 
  which 
  they 
  grew 
  may 
  ripen 
  into 
  a 
  

   single 
  fruit 
  ; 
  or 
  the 
  pistil 
  may 
  grow 
  while 
  the 
  seeds 
  are 
  de- 
  

   veloping, 
  as 
  in 
  the 
  beans 
  and 
  peas, 
  so 
  that 
  the 
  ripened 
  pod 
  is 
  

   hundreds 
  of 
  times 
  as 
  large 
  as 
  the 
  pistil 
  was 
  when 
  fertilization 
  

   took 
  place. 
  

  

  The 
  distribution 
  and 
  germination 
  of 
  seeds 
  was 
  fully 
  dis- 
  

   cussed 
  in 
  previous 
  chapters, 
  and 
  if 
  those 
  chapters 
  are 
  briefly 
  

   reviewed 
  at 
  this 
  time, 
  it 
  will 
  be 
  found 
  helpful. 
  

  

  289. 
  Evolution 
  of 
  plants. 
  The 
  four 
  great 
  divisions 
  of 
  the 
  

   plant 
  kingdom, 
  and 
  the 
  most 
  important 
  classes 
  of 
  these 
  divi- 
  

   sions, 
  have 
  been 
  discussed. 
  It 
  must 
  have 
  been 
  apparent 
  to 
  

   most 
  students 
  that 
  constant 
  increase 
  in 
  the 
  complexity 
  of 
  

   plants 
  was 
  encountered 
  as 
  we 
  passed 
  from 
  lower 
  to 
  higher 
  

   groups. 
  This 
  increase 
  in 
  complexity 
  appears 
  in 
  the 
  nutritive 
  

   parts 
  of 
  plants 
  and 
  in 
  the 
  parts 
  that 
  have 
  to 
  do 
  with 
  repro- 
  

   duction. 
  The 
  process 
  of 
  gradual 
  development 
  from 
  simple 
  to 
  

   complex 
  is 
  the 
  process 
  of 
  evolution. 
  Indeed, 
  there 
  may 
  also 
  

   be 
  evolution 
  in 
  the 
  opposite 
  direction, 
  as 
  occurs 
  when, 
  through 
  

   long 
  and 
  constant 
  changes, 
  simple 
  forms 
  are 
  derived 
  from 
  

   complex 
  ones. 
  Usually 
  evolution 
  is 
  thought 
  of 
  as 
  having 
  

   to 
  do 
  with 
  increase 
  in 
  complexity 
  rather 
  than 
  with 
  decrease. 
  

   The 
  oldest 
  plants 
  of 
  the 
  earth 
  were 
  very 
  simple, 
  and 
  from 
  

   them, 
  in 
  one 
  way 
  or 
  another, 
  more 
  complex 
  ones 
  have 
  devel- 
  

   oped. 
  The 
  simplest 
  plants 
  that 
  are 
  now 
  living 
  have 
  doubtless 
  

  

  