﻿Studies 
  on 
  Synapsis. 
  

  

  283 
  

  

  pupa, 
  or 
  of 
  the 
  early 
  adults 
  just 
  after 
  they 
  make 
  their 
  way 
  out 
  of 
  the 
  gall_ 
  

   After 
  the 
  dissolution 
  of 
  the 
  synaptic 
  knot 
  the 
  differentiation 
  of 
  nurse 
  cells 
  

   and 
  oocytes 
  ensues 
  immediately. 
  The 
  nurse 
  cells 
  in 
  the 
  region 
  of 
  differentia- 
  

   tion 
  possess 
  nuclei 
  with 
  large 
  plasmosomes 
  and 
  innumerable 
  chromatic 
  

   granules 
  ; 
  but 
  fragmentation 
  is 
  preceded 
  by 
  a 
  stage 
  in 
  which 
  the 
  chromatin 
  

   of 
  the 
  nuclei 
  is 
  distributed 
  in 
  the 
  form 
  of 
  lumps 
  of 
  somewhat 
  ragged 
  

   outline 
  (fig. 
  45). 
  A 
  large 
  number 
  of 
  such 
  nuclei 
  were 
  studied, 
  and 
  it 
  seems 
  

   that 
  the 
  number 
  is 
  constant 
  and 
  equal 
  to 
  half 
  the 
  number 
  of 
  chromosomes 
  

   in 
  the 
  oogonia 
  (10-12). 
  I 
  have 
  been 
  unable 
  to 
  satisfy 
  myself 
  that 
  these 
  

   chromatin 
  masses 
  show 
  a 
  division 
  into 
  two 
  parts 
  ; 
  but 
  some 
  sections 
  suggest 
  

   that 
  this 
  is 
  the 
  case, 
  as 
  in 
  the 
  young 
  nurse 
  cells 
  of 
  Philosamia. 
  

  

  The 
  nucleus 
  of 
  the 
  very 
  young 
  oocyte 
  at 
  the 
  same 
  stage 
  shows 
  what 
  

   appears 
  to 
  be 
  the 
  haploid 
  number 
  of 
  somewhat 
  convoluted 
  threads. 
  At 
  

   first 
  I 
  was 
  of 
  the 
  opinion 
  that 
  there 
  is 
  no 
  " 
  diffuse 
  " 
  stage 
  in 
  the 
  oocyte 
  

   nucleus 
  of 
  Orthopelma 
  ; 
  and 
  Hegner 
  omits 
  any 
  mention 
  of 
  one 
  in 
  the 
  case 
  

   of 
  the 
  Chalcid 
  Copidosoma, 
  or 
  the 
  more 
  closely 
  allied 
  form 
  Apanteles. 
  This 
  

   is 
  comprehensible 
  on 
  account 
  of 
  the 
  fact 
  that 
  owing 
  to 
  the 
  rapid 
  develop- 
  

   ment 
  of 
  the 
  oocyte, 
  it 
  is 
  impossible 
  to 
  obtain 
  a 
  complete 
  sequence 
  of 
  stages 
  

   without 
  the 
  examination 
  of 
  a 
  large 
  number 
  of 
  preparations 
  ; 
  and 
  it 
  is 
  easy 
  

   to 
  attribute 
  the 
  disappearance 
  of 
  individually 
  recognisable 
  chromosomes 
  to 
  

   defective 
  preservation. 
  After 
  comparing 
  preparations 
  of 
  the 
  ovaries 
  from 
  

   some 
  fifty 
  females, 
  I 
  am 
  convinced 
  that 
  such 
  a 
  stage 
  does 
  occur, 
  and 
  that 
  it 
  

   is 
  followed 
  by 
  the 
  reappearance 
  of 
  the 
  diploid 
  number 
  as 
  in 
  Copidosoma 
  

   followed 
  by 
  an 
  end-to-end 
  pairing 
  of 
  univalent 
  elements 
  (figs. 
  47 
  and 
  48). 
  I 
  

   am 
  convinced 
  equally 
  that 
  if 
  the 
  case 
  of 
  Copidosoma 
  or 
  Apanteles 
  were 
  

   reinvestigated 
  from 
  this 
  point 
  of 
  view 
  a 
  " 
  diffuse 
  " 
  stage 
  would 
  be 
  found 
  to 
  

   follow 
  synapsis 
  in 
  these 
  genera 
  likewise. 
  An 
  abortive 
  maturation 
  spindle 
  

   is 
  formed 
  by 
  the 
  arrangement 
  of 
  these 
  pairs 
  (eleven 
  in 
  number) 
  on 
  an 
  

   asterless 
  spindle 
  (fig. 
  49). 
  The 
  bivalent 
  chromosomes 
  of 
  the 
  spindle 
  are 
  

   short 
  stout 
  rods 
  as 
  in 
  Rhodites 
  ; 
  in 
  none 
  of 
  the 
  forms 
  examined 
  either 
  by 
  

   Gatenby, 
  Martin, 
  or 
  myself 
  have 
  the 
  chromosomes 
  been 
  found 
  to 
  exhibit 
  

   the 
  filamentous 
  form 
  figured 
  by 
  Hegner, 
  whose 
  illustrations 
  are 
  evidently 
  

   somewhat 
  diagrammatic. 
  As 
  in 
  all 
  these 
  cases 
  the 
  chromosomes 
  condense, 
  

   and 
  the 
  spindle 
  fibres 
  eventually 
  disappear 
  as 
  the 
  nucleoplasmic 
  zone 
  sur- 
  

   rounding 
  the 
  chromatin 
  complex 
  is 
  invaded 
  by 
  the 
  yolk. 
  In 
  other 
  forms 
  

   I 
  have 
  examined 
  the 
  condensation 
  figure 
  is 
  of 
  homogeneous 
  consistency 
  ;■■ 
  

   but 
  in 
  Orthopelma 
  as 
  in 
  Andricus 
  (Hegner) 
  it 
  exhibited 
  a 
  vacuolated 
  

   structure 
  (fig. 
  51). 
  

  

  Chromatin-staining 
  granules 
  occur 
  in 
  the 
  young 
  oocyte, 
  but 
  no 
  secondary 
  

   nuclei. 
  In 
  the 
  full-grown 
  egg 
  there 
  is 
  a 
  triangular 
  area 
  of 
  minute 
  granules 
  

  

  