﻿Occurrence 
  of 
  Multinucleate 
  Cells 
  in 
  Vegetative 
  Tissues. 
  11 
  

  

  the 
  most 
  characteristic 
  examples 
  of 
  phragmospheres 
  for 
  critical 
  examination 
  

   (see 
  Plate 
  1, 
  figs. 
  7-12). 
  In 
  many 
  cases 
  only 
  a 
  single 
  phragmosphere 
  occurs 
  in 
  

   a 
  cell 
  in 
  association 
  with 
  a 
  single 
  dividing 
  nucleus 
  ; 
  in 
  others 
  two 
  phragmo- 
  

   spheres 
  with 
  both 
  pairs 
  of 
  nuclei 
  at 
  the 
  same 
  stage 
  of 
  division 
  may 
  be 
  observed 
  

   in 
  a 
  single 
  cell, 
  or 
  one 
  phragmosphere 
  with 
  its 
  nuclei 
  in 
  telophase, 
  a 
  second 
  

   nucleus 
  in 
  the 
  anaphase 
  of 
  division, 
  and 
  a 
  third 
  nucleus 
  in 
  the 
  resting 
  

   condition 
  may 
  all 
  occur 
  together 
  in 
  one 
  ceil. 
  The 
  history 
  of 
  the 
  phragmo- 
  

   sphere 
  in 
  Anthriscus 
  is 
  precisely 
  as 
  outlined 
  in 
  the 
  preceding 
  paragraph. 
  By 
  

   the 
  disintegration 
  of 
  the 
  spindle 
  and 
  the 
  disappearance 
  of 
  the 
  cell 
  plate 
  before 
  

   it 
  has 
  split 
  into 
  two, 
  the 
  two 
  daughter 
  nuclei, 
  in 
  telophase, 
  are 
  left 
  surrounded 
  

   by 
  a 
  mass 
  of 
  cytoplasm 
  which 
  is 
  partly 
  kinoplasmic 
  in 
  origin. 
  After 
  a 
  time 
  this 
  

   cytoplasmic 
  aggregate 
  becomes 
  slightly 
  vacuolar 
  in 
  its 
  interior 
  ; 
  the 
  vacuole 
  

   gradually 
  enlarges, 
  pushing 
  a 
  hollow 
  shell 
  of 
  dense 
  cytoplasm 
  more 
  and 
  more 
  

   nearly 
  towards 
  the 
  outer 
  boundary 
  of 
  the 
  cell 
  until 
  it 
  merges 
  into 
  the 
  

   peripheral 
  protoplasm. 
  The 
  spindle 
  fibres 
  break 
  down 
  very 
  completely 
  in 
  

   Anthriscus 
  and 
  the 
  phragmospheres 
  show 
  very 
  little 
  of 
  that 
  appearance 
  of 
  

   being 
  composed 
  of 
  radiating 
  fibres 
  which 
  is 
  more 
  clearly 
  seen 
  in 
  some 
  of 
  

   the 
  other 
  plants 
  which 
  we 
  have 
  examined 
  (e.g., 
  Zea 
  Mays, 
  Plate 
  1, 
  figs. 
  1 
  

   and 
  2). 
  In 
  Anthriscus 
  the 
  phragmosphere 
  has 
  a 
  densely 
  granular 
  constitution. 
  

  

  No 
  previous 
  writer 
  appears 
  to 
  have 
  recognised 
  the 
  existence 
  of 
  phragmo- 
  

   spheres, 
  or 
  of 
  anything 
  like 
  them, 
  in 
  ordinary 
  vegetative 
  tissues, 
  but 
  more 
  

   than 
  one 
  observer 
  has 
  recorded 
  the 
  appearance, 
  within 
  the 
  endosperm, 
  of 
  

   structures 
  which 
  may 
  possibly 
  be 
  either 
  related 
  to 
  phragmospheres 
  or 
  

   identical 
  with 
  them. 
  Nemec,* 
  for 
  instance, 
  describes 
  in 
  the 
  endosperm 
  of 
  

   Secede 
  cereale, 
  certain 
  bodies, 
  which 
  he 
  calls 
  " 
  Kerntaschen," 
  which 
  bear 
  some 
  

   resemblance 
  to 
  phragmospheres, 
  but 
  he 
  did 
  not 
  follow 
  out 
  their 
  history 
  in 
  

   detail. 
  Again, 
  certain 
  figures 
  of 
  endosperm 
  cells, 
  taken 
  by 
  the 
  observers 
  to 
  

   suggest 
  end 
  views 
  of 
  nuclear 
  spindles, 
  may 
  possibly 
  indicate 
  phragmospheres 
  

   which 
  have 
  been 
  drawn 
  without 
  a 
  full 
  understanding 
  of 
  their 
  nature.f 
  Among 
  

   Gyrnnosperms, 
  Lawson's} 
  account 
  of 
  the 
  formation 
  of 
  binucleate 
  cells 
  in 
  the 
  

   endosperm 
  of 
  Gryptomcria 
  japonica 
  suggests 
  the 
  occurrence 
  of 
  structures 
  

   somewhat 
  resembling 
  phragmospheres. 
  Beyond 
  these 
  few 
  notes, 
  whose 
  

   relevance 
  is 
  doubtful, 
  we 
  have 
  found 
  nothing 
  in 
  the 
  literature 
  which 
  could 
  

   possibly 
  be 
  construed 
  as 
  a 
  reference 
  to 
  phragmospheres. 
  

  

  * 
  Nemec, 
  B., 
  1 
  Das 
  Problem 
  der 
  Befruchtungsvorgange,' 
  Berlin, 
  pp. 
  112, 
  113 
  (1910). 
  

   t 
  Nemec, 
  B., 
  ibid., 
  Plate 
  2, 
  fig. 
  50 
  ; 
  Buscalioni, 
  L., 
  ' 
  Annuario 
  del 
  R. 
  Istituto 
  Bot. 
  

   di 
  Boma,' 
  vol. 
  7 
  (1898), 
  PI. 
  17, 
  fig. 
  77b 
  and 
  PI. 
  20, 
  fig. 
  140. 
  

  

  % 
  Lawson, 
  A. 
  A., 
  ' 
  Ann. 
  'Bot.,' 
  vol. 
  18, 
  p. 
  427 
  (1904), 
  Plate 
  29, 
  figs. 
  28-32. 
  

  

  