﻿Rickett: 
  Sphaerocarpos 
  Donnellii 
  

  

  355 
  

  

  body 
  

  

  gestive 
  of 
  the 
  germ-tube 
  formed 
  as 
  a 
  result 
  of 
  spore 
  germination. 
  

   As 
  In 
  the 
  latter 
  process, 
  the 
  thallus-plate 
  Is 
  at 
  first 
  usually 
  cup- 
  

   shaped 
  or 
  trough-shaped 
  (Fig. 
  15), 
  and 
  the 
  growing 
  point 
  may 
  

   lie 
  in 
  a 
  median 
  or 
  in 
  a 
  lateral 
  position. 
  The 
  tissues 
  formed 
  to 
  

   right 
  and 
  left 
  of 
  the 
  apical 
  point 
  grow 
  rapidly, 
  so 
  that 
  the 
  latter 
  

   lies 
  at 
  the 
  base 
  of 
  a 
  deep 
  apical 
  notch 
  (Figs. 
  20, 
  21, 
  22). 
  As 
  in 
  

   the 
  case 
  of 
  the 
  sporeling, 
  the 
  first 
  sex 
  organ 
  appears 
  very 
  early 
  

  

  ^ 
  Figs. 
  18-21. 
  Young 
  plants 
  produced 
  by 
  regeneration. 
  Pig. 
  i8. 
  Shoots 
  

   arising 
  from 
  a 
  number 
  of 
  adjoining 
  marginal 
  cells 
  of 
  the 
  ihvolucre. 
  The 
  cellular 
  

   structure 
  of 
  the 
  shoots 
  is 
  not 
  shown. 
  Fig. 
  ig. 
  Filamentous 
  shoot 
  produced 
  from 
  

   the 
  margin 
  of 
  a 
  lobe. 
  Fig. 
  20. 
  The 
  terminal 
  plate 
  of 
  a 
  young 
  plant, 
  showing 
  the 
  

   apical 
  notch: 
  a, 
  young 
  archegonium. 
  Fig. 
  21. 
  Young 
  shoot, 
  consisting 
  of 
  a 
  cylin- 
  

   drical 
  basal, 
  portion 
  and 
  a 
  terminal 
  flat 
  plate: 
  a, 
  archegonium 
  enclosed 
  in 
  young 
  

   involucre. 
  Figs. 
  19-21 
  drawn 
  from 
  living 
  material. 
  Figs. 
  18, 
  19. 
  X 
  35- 
  Figs 
  20 
  

   21. 
  X 
  75- 
  ' 
  ' 
  

  

  (Fig. 
  21), 
  being 
  formed 
  immediately 
  behind 
  the 
  growing 
  point. 
  

   Presumably 
  an 
  apical 
  cell, 
  or 
  group 
  of 
  Initials, 
  is 
  developed 
  In 
  the 
  

   growing 
  region 
  just 
  previous 
  to 
  the 
  formation 
  of 
  the 
  first 
  sex 
  

   organ, 
  since 
  from 
  this 
  point 
  the 
  history 
  of 
  the 
  adventitious 
  shoot 
  

   is 
  identical 
  with 
  that 
  of 
  a 
  typical 
  thallus 
  (5). 
  

  

  In 
  the 
  case 
  of 
  some 
  of 
  the 
  male 
  plants 
  studied, 
  the 
  young 
  

   plant 
  arising 
  by 
  regeneration 
  produced 
  only 
  a 
  few 
  antherldia, 
  

  

  