﻿Studies 
  on 
  Synapsis. 
  

  

  285 
  

  

  seriation 
  of 
  stages 
  permitted 
  a 
  better 
  perspective 
  with 
  respect 
  to 
  those 
  

   changes 
  which 
  occur 
  immediately 
  before 
  the 
  formation 
  of 
  the 
  synaptic 
  knot 
  

   than 
  forms 
  previously 
  discussed. 
  

  

  The 
  preleptotene 
  nuclei 
  of 
  Zasius 
  exhibit 
  a 
  large 
  plasmosome 
  and 
  the 
  

   characteristic 
  clumps 
  of 
  chromatin 
  present 
  in 
  insect 
  gametocytes 
  at 
  this 
  

   stage, 
  and 
  it 
  is 
  possible 
  to 
  trace 
  their 
  transition 
  into 
  the 
  paler 
  and 
  convoluted 
  

   tangle 
  of 
  leptotene 
  filaments 
  in 
  the 
  following 
  stage 
  (fig. 
  53). 
  In 
  Lasius 
  the 
  

   leptotene 
  threads 
  definitely 
  arrange 
  themselves 
  in 
  such 
  a 
  manner 
  as 
  to 
  

   converge 
  towards 
  one 
  pole 
  of 
  the 
  nucleus 
  before 
  passing 
  into 
  synizesis 
  

   (fig. 
  53) 
  ; 
  further, 
  it 
  can 
  be 
  definitely 
  stated 
  that 
  in 
  some 
  " 
  bouquet 
  " 
  nuclei 
  

   there 
  are 
  a 
  large 
  number 
  of 
  pale 
  threads, 
  and 
  in 
  others 
  a 
  much 
  smaller 
  

   number 
  of 
  thicker 
  and 
  more 
  deeply 
  staining 
  filaments 
  (fig. 
  53), 
  indicating 
  a 
  

   possible 
  condition 
  of 
  pachynema. 
  

  

  Synizesis 
  is 
  illustrated 
  in 
  fig. 
  54. 
  Till 
  this 
  stage 
  no 
  distinction 
  can 
  be 
  

   recognised 
  in 
  the 
  cells 
  of 
  the 
  terminal 
  chamber. 
  The 
  haploid 
  number 
  of 
  

   filaments 
  appear 
  after 
  the 
  break 
  up 
  of 
  synizesis. 
  Differentiation 
  follows 
  with 
  

   remarkable 
  alacrity. 
  Already 
  among 
  the 
  cells 
  showing 
  nuclei 
  with 
  separate 
  

   pachytene 
  filaments 
  (after 
  synizesis) 
  two 
  types 
  can 
  be 
  distinguished. 
  In 
  the 
  

   future 
  oocytes 
  the 
  surrounding 
  cytoplasm 
  is 
  already 
  more 
  bulky 
  and 
  granular. 
  

   In 
  the 
  case 
  of 
  oocytes 
  a 
  diplotene 
  stage 
  is 
  intercalated 
  (fig. 
  56). 
  What 
  

   follows 
  in 
  each 
  case 
  is 
  in 
  the 
  main 
  similar 
  to 
  the 
  course 
  of 
  events 
  in 
  the 
  

   forms 
  treated 
  earlier 
  in 
  this 
  paper. 
  The 
  chromatin 
  of 
  the 
  nurse 
  cell 
  nuclei 
  

   undergoes 
  fragmentation 
  into 
  minute 
  granules 
  : 
  at 
  a 
  very 
  early 
  stage 
  the 
  large 
  

   and 
  characteristic 
  nucleolus 
  can 
  be 
  seen. 
  The 
  oocyte 
  nucleus 
  shows 
  no 
  

   plasmosome 
  ; 
  the 
  filaments 
  suffer 
  a 
  great 
  diminution 
  of 
  staining 
  capacity 
  and 
  

   lose 
  their 
  visible 
  identity. 
  There 
  is 
  contemporaneously 
  a 
  reduction 
  of 
  the 
  

   chromatin-content 
  of 
  the 
  nucleus. 
  In 
  the 
  early 
  stages 
  of 
  growth 
  the 
  

   nucleoli 
  of 
  the 
  nurse 
  cells 
  constantly 
  undergo 
  fragmentation 
  and 
  eject 
  

   particles, 
  which 
  can 
  be 
  seen 
  to 
  pass 
  into 
  the 
  protoplasmic 
  strand 
  connecting 
  

   the 
  young 
  oocyte 
  with 
  the 
  nurse 
  chamber. 
  

  

  The 
  Late 
  Ovarian 
  Oocyte. 
  

  

  The 
  nucleus 
  remains 
  in 
  this 
  condition 
  until 
  about 
  the 
  time 
  the 
  egg 
  is 
  laid, 
  

   when 
  various 
  authors 
  have 
  described 
  a 
  typical 
  spindle. 
  None 
  of 
  the 
  peculiar 
  

   phases 
  that 
  are 
  intercalated 
  in 
  the 
  late 
  ovarian 
  oocyte 
  of 
  parasitic 
  species 
  like 
  

   Cynips 
  or 
  Copidosoma 
  occur. 
  Since 
  in 
  both 
  the 
  ant 
  and 
  the 
  bee 
  the 
  first 
  

   polar 
  spindle 
  is 
  already 
  formed 
  when 
  the 
  egg 
  is 
  laid 
  the 
  late 
  maturation 
  

   prophases 
  must 
  be 
  studied 
  immediately 
  before 
  the 
  laying 
  of 
  the 
  egg. 
  With 
  

   this 
  end 
  in 
  view 
  I 
  have 
  examined 
  the 
  oldest 
  eggs 
  in 
  young 
  queens 
  of 
  Lasius 
  

   without 
  success 
  and 
  preparations 
  from 
  Formica 
  rufa 
  of 
  the 
  ovarioles 
  of 
  queens 
  

  

  