﻿Studies 
  on 
  Synapsis. 
  

  

  275 
  

  

  "become 
  divided 
  to 
  form 
  rosettes, 
  and 
  it 
  is 
  in 
  the 
  fully 
  formed 
  rosettes 
  of 
  the 
  

   larva 
  just 
  before 
  pupation 
  that 
  the 
  synaptic 
  stages 
  are 
  to 
  be 
  traced. 
  

  

  The 
  stages 
  of 
  synapsis 
  in 
  Rhodites 
  are 
  here 
  described 
  for 
  the 
  first 
  time, 
  and 
  

   I 
  am 
  able 
  to 
  supply 
  fuller 
  details 
  than 
  in 
  the 
  case 
  of 
  Cynips. 
  As 
  in 
  the 
  

   latter, 
  the 
  preleptotene 
  nuclei 
  display 
  irregular 
  masses 
  of 
  chromatin. 
  Nurse 
  

   cells 
  cannot 
  be 
  distinguished 
  from 
  functional 
  oocytes 
  until 
  after 
  synizesis, 
  

   and 
  the 
  nuclear 
  history 
  of 
  the 
  former 
  may 
  be 
  dealt 
  with 
  first 
  : 
  — 
  

  

  1. 
  Leptonema. 
  — 
  The 
  chromatin 
  of 
  the 
  nucleus 
  forms 
  a 
  tangle 
  of 
  pale 
  

   convoluted 
  threads, 
  which 
  are 
  too 
  intricately 
  crossed 
  to 
  permit 
  the 
  possibility 
  

   of 
  counting 
  them 
  (figs. 
  21, 
  22). 
  

  

  2. 
  Synizesis. 
  — 
  The 
  leptotene 
  threads 
  increase 
  in 
  staining 
  capacity 
  and 
  

   contract 
  away 
  from 
  the 
  nuclear 
  membrane 
  in 
  a 
  compact 
  knot 
  (figs. 
  23-25). 
  

  

  3. 
  Post 
  Synaptic 
  spireme. 
  — 
  As 
  synizesis 
  dissolves, 
  a 
  spireme 
  emerges, 
  which 
  

   breaks 
  up 
  into 
  pachytene 
  filaments 
  (figs. 
  26, 
  27), 
  of 
  which 
  in 
  over 
  20 
  counter 
  

   about 
  9 
  are 
  clearly 
  present. 
  

  

  4. 
  Diplotene. 
  — 
  Immediately 
  after 
  the 
  foregoing, 
  the 
  pachytene 
  threads 
  are 
  

   seen 
  to 
  be 
  split 
  lengthwise; 
  these 
  double 
  threads 
  shorten 
  up 
  into 
  rectangular 
  

   masses 
  of 
  ragged 
  outline, 
  which 
  are 
  still 
  evidently 
  double. 
  These 
  masses 
  

   break 
  up 
  into 
  minute 
  granules 
  which 
  are 
  dispersed 
  throughout 
  the 
  nucleo- 
  

   plasm 
  of 
  the 
  fully-formed 
  nucleus 
  of 
  the 
  nurse 
  cell 
  (figs. 
  28-30). 
  

  

  The 
  foregoing 
  account 
  shows 
  striking 
  similarity 
  to 
  Dederer's 
  recent 
  work 
  

   on 
  the 
  moth 
  Philosamia, 
  in 
  which 
  the 
  history 
  of 
  the 
  nurse 
  cells 
  is 
  almost 
  

   identical. 
  

  

  The 
  young 
  oocyte 
  nucleus, 
  after 
  passing 
  through 
  the 
  stages 
  of 
  leptonema, 
  

   synizesis, 
  and 
  pachynema, 
  begins 
  to 
  show 
  a 
  greatly 
  diminished 
  staining 
  

   capacity 
  ; 
  it 
  becomes 
  difficult 
  to 
  trace 
  separate 
  threads, 
  though 
  it 
  seems 
  likely 
  

   from 
  some 
  preparations 
  that 
  the 
  diploid 
  number 
  is 
  present. 
  A 
  striking 
  fact 
  

   is 
  that 
  the 
  diminution 
  of 
  the 
  staining 
  capacity 
  of 
  the 
  nucleus 
  coincides 
  with 
  

   the 
  appearance 
  of 
  nuclear 
  granules 
  on 
  the 
  nuclear 
  membrane 
  within 
  the 
  

   nucleus 
  and 
  in 
  the 
  surrounding 
  cytoplasm, 
  thus 
  confirming 
  the 
  opinion 
  

   previously 
  expressed 
  that 
  the 
  chromatin-staining 
  granules 
  in 
  the 
  young 
  egg 
  

   of 
  Cynips 
  are 
  of 
  nuclear 
  origin 
  (fig. 
  30). 
  During 
  the 
  greater 
  part 
  of 
  the 
  

   growth 
  period 
  the 
  nucleus 
  remains 
  in 
  the 
  "diffuse" 
  stage, 
  i.e., 
  the 
  visible 
  

   identity 
  of 
  the 
  chromatin 
  elements 
  can 
  no 
  longer 
  be 
  traced 
  with 
  certainty 
  ; 
  

   but 
  in 
  the 
  very 
  late 
  pupal 
  ovary 
  nuclei 
  can 
  be 
  found 
  in 
  which 
  long 
  thin 
  

   filamentous 
  chromosomes 
  are 
  present, 
  staining 
  deeply 
  ; 
  their 
  number 
  is 
  

   about 
  18. 
  

  

  The 
  oocyte 
  is 
  oval 
  during 
  the 
  growth 
  period. 
  The 
  cytoplasm 
  at 
  first 
  

   projects 
  into 
  the 
  adjacent 
  nurse 
  chamber 
  ; 
  but 
  by 
  the 
  time 
  the 
  imagines 
  

   emerge 
  the 
  egg 
  has 
  reached 
  the 
  full 
  size, 
  the 
  follicle 
  is 
  complete 
  and 
  reduced 
  

  

  