﻿Farr: 
  Pollen-mother-cell 
  of 
  Cobaea 
  scandens 
  alba 
  335 
  

  

  in 
  the 
  study 
  of 
  spore 
  formation 
  In 
  PUoholus 
  and 
  Fuligo 
  that 
  a 
  dif- 
  

   ferentiation 
  of 
  the 
  cytoplasm 
  might 
  occur 
  during 
  the 
  process 
  of 
  

   cleavage. 
  He 
  found 
  "hyaline 
  areas" 
  occurring 
  midway 
  between 
  

   each 
  pair 
  of 
  nuclei. 
  According 
  to 
  his 
  account 
  the 
  cytoplasm 
  

   appears 
  as 
  if 
  the 
  protoplasmic 
  mass 
  had 
  contracted 
  about 
  each 
  

   nucleus 
  as 
  a 
  center, 
  thus 
  leaving 
  irregular, 
  furrow-shaped, 
  less 
  

   dense 
  spaces 
  in 
  the 
  middle 
  region 
  between 
  the 
  two 
  nuclei. 
  

  

  In 
  Cobaea 
  the 
  less 
  dense 
  areas 
  referred 
  to 
  above 
  are 
  practically 
  

   free 
  from 
  any 
  granular 
  masses, 
  and 
  appear 
  very 
  clear. 
  'The 
  

   term 
  "hyaline 
  areas" 
  has 
  not 
  been 
  used 
  because 
  the 
  discussion 
  

   and 
  figures 
  by 
  Harper 
  concerning 
  the 
  somewhat 
  similar 
  regions 
  in 
  

   the 
  dividing 
  cells 
  of 
  the 
  fungi 
  indicate 
  a 
  condition 
  of 
  greater 
  

   transparency 
  than 
  is 
  evident 
  in 
  Cobaea. 
  These 
  areas 
  also 
  do 
  not 
  

   appear 
  so 
  markedly 
  wedge-shaped 
  as 
  those 
  shown 
  by 
  Harper 
  in 
  

   Fiiligo 
  (J. 
  8). 
  They 
  are, 
  however, 
  in 
  general 
  form, 
  not 
  at 
  all 
  

   unlike 
  that 
  shown 
  by 
  the 
  same 
  author 
  in 
  his 
  /. 
  9. 
  Aside 
  from 
  these 
  

   differences, 
  the 
  description 
  of 
  the 
  "hyaline 
  areas" 
  in 
  Fuligo 
  and 
  

   Pilobolus 
  might 
  be 
  applied 
  directly 
  to 
  the 
  less 
  dense 
  areas 
  in 
  

  

  Cobaea 
  without 
  any 
  alteration. 
  

  

  The 
  appearance 
  of 
  such 
  cytoplasmic 
  differentiation 
  in 
  these 
  

   widely 
  separated 
  forms 
  would 
  seem 
  to 
  be 
  of 
  significance 
  in 
  estab- 
  

   lishing 
  the 
  similarity 
  of 
  the 
  processes 
  concerned 
  in 
  the 
  divisions 
  by 
  

   furrowing, 
  and 
  would 
  also 
  give 
  strength 
  to 
  the 
  idea 
  that 
  they 
  are 
  

   worthy 
  of 
  all 
  of 
  the 
  recognition 
  given 
  them 
  by 
  Harper 
  in 
  the 
  

   fungi. 
  Since 
  these 
  less 
  dense 
  areas 
  may 
  be 
  found 
  to 
  occur 
  in 
  

   both 
  dicotyledons 
  and 
  fungi, 
  it 
  must 
  be 
  remembered 
  that 
  the 
  con- 
  

   ditions 
  under 
  which 
  they 
  are 
  found 
  are 
  quite 
  similar. 
  In 
  all 
  cases 
  

   they 
  appear 
  in 
  connection 
  with 
  the 
  cytoplasmic 
  division 
  of 
  a 
  

   multinucleate 
  cell 
  In 
  which 
  cell-plates 
  are 
  not 
  formed. 
  In 
  all 
  

   instances 
  so 
  far 
  reported 
  they 
  bound 
  off 
  a 
  single 
  nucleus 
  and 
  

   never 
  a 
  group 
  of 
  nuclei. 
  They 
  are 
  also 
  the 
  early 
  Indicators 
  that 
  

   the 
  process 
  of 
  clea\'age 
  will 
  result 
  In 
  uninucleate 
  masses 
  with 
  

   approximately 
  equal 
  amounts 
  of 
  cytoplasm. 
  

  

  A 
  comparison 
  of 
  the 
  pollen-mother-cells 
  of 
  the 
  two 
  forms 
  with 
  

   reference 
  to 
  the 
  breadth 
  of 
  the 
  progressing 
  furrow 
  will 
  show 
  that 
  

   they 
  are 
  much 
  more 
  narrow 
  in 
  Cobaea 
  than 
  In 
  Nicotiana. 
  A 
  

   further 
  comparison 
  of 
  the 
  maximum 
  thickening 
  of 
  the 
  cell-walls 
  

   in 
  the 
  two 
  forms 
  shows 
  that 
  it 
  reaches 
  a 
  thickness 
  of 
  one-tenth 
  of 
  

  

  