﻿354 
  

  

  Rickett: 
  Sphaerocarpos 
  Doxnellii 
  

  

  Very 
  often, 
  the 
  surrounding 
  cells 
  being 
  largely 
  dead 
  or 
  dying, 
  

   the 
  cells 
  which 
  form 
  the 
  new 
  plants 
  assume 
  a 
  globular 
  form 
  and 
  

   stand 
  out 
  from 
  the 
  surrounding 
  tissue. 
  This 
  is 
  especially 
  true 
  

   when 
  regeneration 
  occurs 
  from 
  the 
  midrib. 
  Such 
  a 
  case 
  is 
  shown 
  

   in 
  Fig. 
  17. 
  Here 
  also 
  there 
  is 
  a 
  strong 
  suggestion 
  that 
  a 
  group 
  of 
  

   cells 
  is 
  concerned 
  in 
  the 
  production 
  of 
  a 
  single 
  new 
  plant. 
  

  

  Figs. 
  13-17- 
  The 
  further 
  development 
  of 
  shoots 
  produced 
  by 
  regeneration 
  from 
  

   involucres 
  and 
  lobes. 
  The 
  shading 
  indicates 
  the 
  density 
  of 
  the 
  cell 
  contents 
  in 
  the 
  

   new 
  plants. 
  Fig. 
  13. 
  Regeneration 
  from 
  a 
  single 
  cell 
  of 
  a 
  lobe. 
  Fig. 
  14. 
  Cell 
  

   masses 
  produced 
  by 
  the 
  division 
  of 
  a 
  number 
  of 
  adjoining 
  mother 
  cells 
  of 
  ah 
  involucre. 
  

   The 
  cell 
  contents 
  were 
  so 
  dense 
  that 
  the 
  cell 
  walls 
  could 
  not 
  be 
  distinguished. 
  Figs. 
  

   15. 
  16. 
  Regeneration 
  from 
  the 
  marg'ins 
  of 
  lobes. 
  Fig. 
  17. 
  Regeneration 
  from 
  

   the 
  midrib: 
  y. 
  cut 
  surface; 
  r. 
  rhizoids. 
  All 
  drawn 
  from 
  living 
  material. 
  X 
  75- 
  

  

  In 
  the 
  course 
  of 
  the 
  usual 
  history, 
  after 
  the 
  young 
  plant 
  has 
  

   developed 
  into 
  a 
  small 
  globular 
  or 
  cylindrical 
  mass, 
  a 
  fiat 
  plate 
  is 
  

   formed 
  as 
  the 
  result 
  of 
  the 
  continued 
  division 
  of 
  a 
  group 
  of 
  cells 
  

   at 
  the 
  tip 
  of 
  the 
  structure. 
  Figs. 
  15 
  and 
  16 
  represent 
  cases 
  in 
  

   which 
  this 
  process 
  is 
  taking 
  place 
  at 
  an 
  early 
  stage; 
  in 
  Figs. 
  17, 
  

   21, 
  22, 
  and 
  23 
  the 
  original 
  cell 
  mass 
  has 
  developed 
  into 
  a 
  long 
  and 
  

  

  