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  INTRODUCTION 
  TO 
  BOTANY 
  

  

  capsule 
  in 
  which 
  the 
  asexual 
  spores 
  are 
  formed 
  is 
  a 
  complex 
  

   structure. 
  The 
  stalk 
  upon 
  which 
  it 
  is 
  borne 
  is 
  known 
  as 
  the 
  

   seta, 
  which 
  means 
  " 
  bristle" 
  or 
  " 
  hair." 
  In 
  the 
  capsule 
  itself 
  the 
  

   cap 
  which 
  covers 
  the 
  tip 
  is 
  known 
  as 
  the 
  w///////v, 
  which 
  means 
  

  

  '1 
  il." 
  The 
  calyptra 
  is 
  the 
  old 
  archegonium 
  wall 
  that 
  was 
  

  

  carried 
  upward 
  by 
  the 
  developing 
  stalk. 
  Beneath 
  the 
  calvp- 
  

   tra 
  is 
  the 
  mouth, 
  or 
  perixtome, 
  of 
  the 
  capsule, 
  and 
  over 
  the 
  

   mouth 
  is 
  an 
  easily 
  removed 
  lid, 
  the 
  opercuhan. 
  Beneath 
  this 
  

   lid 
  peculiar 
  teeth 
  (fig. 
  203, 
  D 
  and 
  #) 
  surround 
  the 
  mouth, 
  and 
  

   through 
  these 
  teeth 
  the 
  spores 
  are 
  dropped 
  or 
  thrown 
  as 
  

   changes 
  in 
  moisture 
  cause 
  the 
  teeth 
  to 
  move 
  in 
  and 
  out. 
  

   This 
  elaborate 
  arrangement 
  is 
  thought 
  to 
  secure 
  thorough 
  

   distribution 
  of 
  the 
  asexual 
  spores 
  of 
  the 
  mosses. 
  

  

  251. 
  Alternate 
  stages 
  in 
  the 
  life 
  of 
  the 
  mosses. 
  It 
  is 
  evident 
  

   that 
  in 
  the 
  mosses 
  sexual 
  and 
  asexual 
  reproduction 
  are 
  limited 
  

   to 
  distinct 
  parts 
  of 
  the 
  plant. 
  A 
  moss 
  spore, 
  when 
  it 
  ger- 
  

   minates, 
  produces 
  not 
  the 
  part 
  of 
  the 
  plant 
  from 
  which 
  the 
  

   spore 
  grew, 
  but 
  the 
  other 
  part. 
  Asexual 
  spores 
  germinate 
  

   and 
  produce 
  protonema, 
  from 
  which 
  the 
  leafy 
  shoot 
  grows 
  

   by 
  means 
  of 
  buds; 
  the 
  sex 
  spore, 
  or 
  ob'spore, 
  germinates 
  and 
  

   produces 
  the 
  leafless 
  stalk, 
  upon 
  which 
  grows 
  the 
  capsule 
  in 
  

   which 
  asexual 
  spores 
  are 
  formed. 
  It 
  is 
  customary 
  to 
  speak 
  

   of 
  that 
  part 
  of 
  a 
  plant 
  which 
  produces 
  the 
  asexual 
  spores 
  as 
  

   the 
  sporophyte 
  (spore 
  plant), 
  and 
  of 
  the 
  part 
  that 
  produces 
  

   the 
  sex 
  spore 
  as 
  the 
  gametopTiyte 
  (gamete 
  plant), 
  or 
  the 
  part 
  

   of 
  the 
  plant 
  which 
  produces 
  the 
  sex 
  cells. 
  The 
  sporophyte 
  is 
  

   therefore 
  the 
  asexual 
  generation 
  of 
  the 
  moss, 
  and 
  the 
  gameto- 
  

   phyte 
  the 
  sexual 
  generation, 
  and 
  they 
  alternate 
  in 
  completing 
  

   the 
  life 
  round 
  of 
  the 
  whole 
  plant. 
  This 
  relation 
  of 
  the 
  two 
  

   phases 
  is 
  spoken 
  of 
  as 
  the 
  alternation 
  of 
  generations. 
  The 
  fact 
  

   that 
  the 
  protonema 
  and 
  the 
  leafy 
  shoot 
  are 
  distinct 
  structures 
  

   does 
  not 
  make 
  a 
  third 
  phase 
  in 
  the 
  alternation, 
  for 
  the 
  reason 
  

   that 
  there 
  is 
  no 
  spore 
  intervening 
  between 
  them. 
  Also, 
  the 
  

   term 
  alternation, 
  as 
  used, 
  refeES 
  only 
  to 
  sexual 
  and 
  asexual 
  

   generations, 
  and 
  not 
  to 
  cases 
  such 
  as 
  that 
  of 
  the 
  wheat 
  rust, 
  

   where 
  the 
  asexual 
  phase 
  appears 
  in 
  several 
  different 
  forms. 
  

  

  