﻿THE 
  MAIOTIC 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  521 
  

  

  countered. 
  These 
  become 
  much 
  more 
  frequent 
  at 
  later 
  stages, 
  

   and 
  they 
  clearly 
  owe 
  their 
  origin 
  to 
  the 
  fusion 
  of 
  ends 
  

   previously 
  free 
  from 
  each 
  other. 
  Again, 
  the 
  two 
  sides 
  may 
  

   be 
  twisted 
  over 
  each 
  other 
  whilst 
  both 
  ends 
  remain 
  discon- 
  

   nected. 
  

  

  Meanwhile 
  the 
  spore-mother-cells 
  have 
  become 
  completely 
  

   detached 
  from 
  each 
  other 
  by 
  the 
  solution 
  of 
  the 
  middle 
  

   lamella, 
  and 
  the 
  excentric 
  position 
  of 
  the 
  nucleus 
  is 
  strongly 
  

   marked. 
  A 
  curious 
  appearance 
  is 
  seen 
  in 
  each 
  cell, 
  at 
  this 
  

   and 
  earlier 
  stages, 
  in 
  the 
  vicinity 
  of 
  the 
  nucleus. 
  In 
  the 
  

   cytoplasm 
  at 
  the 
  narrower 
  end 
  of 
  the 
  spore-mother-cell 
  a 
  

   remarkable 
  vacuolar 
  arrangement 
  of 
  the 
  fibrous 
  cytoplasm 
  

   is 
  regularly 
  seen 
  as 
  a 
  highly 
  characteristic 
  feature 
  that 
  per- 
  

   sists 
  through 
  the 
  greater 
  part 
  of 
  the 
  whole 
  stage 
  of 
  prophase 
  

   (fig. 
  23). 
  It 
  seems 
  to 
  have 
  nothing 
  to 
  do 
  with 
  the 
  spindle 
  

   formation 
  that 
  occurs 
  later, 
  and 
  without 
  hazarding 
  any 
  theory 
  

   as 
  to 
  its 
  significance, 
  it 
  may 
  perhaps 
  be 
  suggested 
  that 
  it 
  

   possibly 
  indicates 
  a 
  withdrawal 
  into 
  the 
  nucleus 
  of 
  substances 
  

   previously 
  contained 
  in 
  the 
  extra-nuclear 
  cytoplasm. 
  As 
  

   the 
  formation 
  of 
  the 
  definitive 
  chromosomes 
  proceeds, 
  rapid 
  

   changes 
  begin 
  to 
  affect 
  the 
  tapetal 
  tissue. 
  The 
  cells 
  com- 
  

   posing 
  this 
  nutritive 
  layer 
  have 
  become 
  enlarged, 
  and 
  the 
  

   nuclei 
  have 
  multiplied, 
  first, 
  niitotically, 
  and 
  later 
  on 
  by 
  an 
  

   abbreviated 
  process 
  more 
  akin 
  to 
  amitosis. 
  The 
  cell 
  walls 
  

   ultimately 
  break 
  down, 
  and 
  the 
  cytoplasmic 
  contents, 
  together 
  

   with 
  the 
  nuclei, 
  escape 
  into 
  the 
  interspaces 
  between 
  the 
  spore- 
  

   mother-cells. 
  The 
  nuclei 
  long 
  retain 
  that 
  curious 
  condition 
  

   of 
  prophase 
  so 
  characteristic 
  of 
  the 
  nuclei 
  of 
  many 
  actively 
  

   secreting 
  gland-cells. 
  Gradually, 
  however, 
  they 
  undergo 
  dis- 
  

   integration 
  in 
  the 
  slimy 
  mass 
  that 
  now 
  fills 
  the 
  interstices 
  

   between 
  the 
  separated 
  spore-mother-cells. 
  

  

  Meanwhile 
  the 
  chromatic 
  thread 
  has 
  segmented 
  with 
  the 
  

   definitive 
  chromosomes, 
  or 
  if 
  previously 
  in 
  reality 
  discon- 
  

   tinuous, 
  it 
  at 
  least 
  now 
  can 
  be 
  certainly 
  so 
  recognised. 
  Many 
  

   of 
  these 
  young 
  chromosomes 
  consist 
  at 
  first 
  of 
  U-shaped 
  

   loops, 
  with 
  sinuously 
  curved 
  limbs. 
  Sometimes 
  the 
  limbs 
  are 
  

   twisted 
  round 
  each 
  other, 
  and 
  the 
  impression 
  is 
  conveyed 
  to 
  

  

  VOJ.. 
  48, 
  TART 
  4. 
  NEW 
  SERIES. 
  38 
  

  

  