﻿Rickett: 
  Sphaerocarpos 
  Donnellii 
  357 
  

  

  » 
  

  

  whole 
  is 
  partly 
  dead, 
  or 
  when 
  portions 
  of 
  it 
  are 
  separated 
  or 
  partly 
  

   separated 
  from 
  the 
  rest 
  under 
  conditions 
  favorable 
  for 
  growth. 
  

  

  2. 
  Plants 
  produced 
  by 
  regeneration 
  originate 
  for 
  the 
  most 
  part 
  

   in 
  a 
  single 
  cell, 
  which 
  divides 
  irregularly 
  to 
  form 
  a 
  cell 
  mass 
  whose 
  

   shape 
  is 
  dependent 
  on 
  environmental 
  conditions. 
  It 
  is 
  possible 
  

   that 
  in 
  some 
  cases 
  this 
  cell 
  mass 
  may 
  originate 
  from 
  several 
  ad- 
  

   joining 
  cells 
  of 
  the 
  parent 
  plant 
  instead 
  of 
  from 
  one 
  cell 
  only, 
  

  

  3. 
  There 
  is 
  a 
  tendency 
  towards 
  the 
  formation 
  of 
  a 
  two-sided 
  

  

  ■ 
  

  

  apical 
  cell 
  in 
  the 
  early 
  stages, 
  this 
  being 
  most 
  marked 
  when 
  con- 
  

   ditions 
  are 
  comparatively 
  unfavorable. 
  This 
  tendency 
  may 
  

   lead 
  to 
  the 
  formation 
  under 
  unfavorable 
  conditions 
  of 
  a 
  long, 
  

   narrow, 
  ribbon-shaped 
  plant. 
  

  

  4. 
  The 
  development 
  of 
  the 
  first 
  cell 
  mass, 
  globular, 
  cylindrical, 
  

   or 
  ribbon-like, 
  into 
  a 
  typical 
  thallus 
  takes 
  place 
  in 
  a 
  manner 
  

   entirely 
  analogous 
  to 
  the 
  development 
  of 
  a 
  mature 
  thallus 
  from 
  

   the 
  germ-tube 
  produced 
  by 
  a 
  spore 
  on 
  germination. 
  

  

  Department 
  of 
  Botany, 
  

  

  University 
  of 
  Wisconsin 
  

  

  Literature 
  cited 
  

  

  1. 
  Douin, 
  C. 
  Le 
  Sphaerocarpus 
  terrestris 
  Sm. 
  Rev. 
  Bryol. 
  30: 
  44-57. 
  

  

  /- 
  1-2 
  1, 
  1903. 
  

  

  2. 
  Douin, 
  C, 
  & 
  Douin, 
  R, 
  Note 
  sur 
  les 
  Sphaerocarpus. 
  Rev. 
  Gen. 
  

  

  Bot. 
  29: 
  129-136, 
  1917. 
  

  

  3. 
  Goebel, 
  K. 
  Archegoniatenstudien. 
  XL 
  Weitere 
  Untersuchungen 
  

  

  uber 
  Keimung 
  und 
  Regeneration 
  bei 
  Riella 
  und 
  Sphaerocarpus. 
  

   Flora 
  97: 
  192-215. 
  /. 
  I-2J. 
  1907. 
  

  

  4. 
  Leitgeb, 
  H. 
  Sphaerocarpus. 
  Untersuchungen 
  iiber 
  die 
  Lebermoose 
  

  

  4: 
  63-74. 
  pl' 
  S(J. 
  9-18), 
  9, 
  1879. 
  

  

  5. 
  Rickett, 
  H. 
  W. 
  The 
  development 
  of 
  the 
  thallus 
  of 
  Sphaerocarpos 
  

  

  Donnellii 
  Aust. 
  Amer. 
  Jour. 
  Bot. 
  7: 
  182-194. 
  pL 
  g-12 
  +/. 
  i. 
  

   1920. 
  

  

  t 
  

  

  