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  Mr. 
  L. 
  T. 
  Hogben. 
  

  

  full 
  story 
  of 
  their 
  genesis 
  would 
  then 
  be 
  as 
  follows 
  : 
  as 
  the 
  oocyte 
  nucleus 
  

   enters 
  upon 
  the 
  diffuse 
  stage 
  its 
  diminution 
  of 
  staining 
  capacity 
  is 
  seen 
  

   to 
  synchronise 
  with 
  the 
  ejection 
  of 
  chromatin-staining 
  particles 
  in 
  the 
  

   surrounding 
  cytoplasm 
  ; 
  these 
  particles 
  increase 
  in 
  volume 
  and 
  subsequently 
  

   undergo 
  fragmentation, 
  becoming 
  limited 
  by 
  an 
  enclosing 
  membrane, 
  and 
  so 
  

   simulating 
  the 
  appearance 
  of 
  true 
  nuclei. 
  Heguer 
  states 
  that 
  secondary 
  

   nuclei 
  in 
  Apanteles 
  are 
  only 
  found 
  for 
  a 
  brief 
  period 
  in 
  the 
  egg 
  : 
  this 
  is 
  

   probably 
  the 
  case 
  in 
  Synergus 
  also. 
  

  

  4. 
  Orthopelma 
  Luteolator. 
  

  

  The 
  later 
  maturation 
  prophases, 
  as 
  stated 
  in 
  the 
  introduction 
  to 
  the 
  

   present 
  communication, 
  have 
  been 
  described 
  briefly 
  by 
  Hegner, 
  Silvestri, 
  

   Martin, 
  and 
  Gatenby 
  in 
  certain 
  Chalcididae 
  and 
  in 
  the 
  Braconid, 
  Apanteles, 
  

   I 
  have 
  examined 
  various 
  species 
  of 
  both 
  families, 
  including 
  Torymus, 
  

   Microgaster 
  and 
  Hecabolus 
  ; 
  but 
  while 
  confirming 
  in 
  general 
  their 
  con- 
  

   clusions, 
  have 
  insufficient 
  new 
  matter 
  to 
  merit 
  record. 
  To 
  emphasise, 
  

   however, 
  the 
  general 
  occurrence 
  of 
  the 
  phenomena 
  that 
  have 
  been 
  described 
  

   in 
  Cynips 
  and 
  Rhodites 
  among 
  the 
  parasitic 
  Hymenoptera, 
  it 
  will 
  suffice 
  

   to 
  give 
  a 
  brief 
  survey 
  of 
  the 
  history 
  of 
  the 
  oocyte 
  in 
  a 
  representative 
  of 
  a 
  

   family 
  upon 
  which 
  no 
  cytological 
  work 
  has 
  been 
  performed 
  up 
  to 
  date. 
  

   Orthopelma 
  luteolator 
  is 
  one 
  of 
  the 
  Cryptine 
  Ichneumonidae, 
  which 
  parasitises 
  

   the 
  galls 
  of 
  -Rhodites 
  probably 
  as 
  a 
  parasite 
  on 
  the 
  gallmaker 
  itself. 
  A 
  very 
  

   large 
  quantity 
  of 
  this 
  species 
  was 
  bred 
  in 
  the 
  course 
  of 
  my 
  experiments 
  

   with 
  Rhodites 
  itself 
  ; 
  and 
  I 
  am 
  indebted 
  to 
  Mr. 
  Turner, 
  of 
  the 
  British 
  

   Museum, 
  for 
  assistance 
  in 
  the 
  identification 
  of 
  this 
  species. 
  

  

  In 
  the 
  larva, 
  just 
  before 
  pupation 
  begins, 
  the 
  ovaries 
  consist 
  of 
  rosettes, 
  

   the 
  cells 
  of 
  which 
  are 
  undergoing 
  segmentation 
  by 
  synchronous 
  divisions. 
  

   This 
  is 
  shown 
  by 
  the 
  fact 
  that 
  mitoses 
  are 
  rare 
  ; 
  but 
  where 
  they 
  occur 
  they 
  

   are 
  always 
  seen 
  in 
  the 
  same 
  group 
  of 
  cells 
  altogether 
  (fig. 
  42). 
  The 
  number 
  

   of 
  chromosomes 
  in 
  dividing 
  oogonia 
  appears 
  to 
  be 
  about 
  22. 
  The 
  eggs 
  do 
  

   not 
  all 
  develop 
  at 
  the 
  same 
  time, 
  as 
  in 
  the 
  Cynipidse, 
  this 
  insect 
  having 
  a 
  

   longer 
  life 
  in 
  the 
  adult 
  condition. 
  In 
  imagines 
  that 
  have 
  just 
  emerged, 
  

   synapsis 
  can 
  still 
  be 
  studied 
  in 
  the 
  terminal 
  portion 
  of 
  the 
  egg-tubes, 
  which 
  

   are 
  of 
  the 
  usual 
  monothalamous 
  type. 
  Unfortunately, 
  however, 
  the 
  nuclei 
  

   are 
  minute, 
  the 
  whole 
  egg 
  in 
  Orthopelma 
  being 
  in 
  size 
  about 
  a 
  fifth 
  that 
  of 
  

   Rhodites. 
  No 
  differential 
  divisions 
  either 
  of 
  the 
  nucleus 
  or 
  cytoplasm 
  occur 
  

   in 
  the 
  rosettes, 
  the 
  cells 
  of 
  which 
  are 
  equipotential. 
  There 
  is 
  no 
  visible 
  

   distinction 
  between 
  nurse 
  cells 
  and 
  oocyte 
  until 
  after 
  synizesis 
  (figs. 
  43, 
  44). 
  

   The 
  ovaries 
  of 
  the 
  adult 
  contain 
  oocytes 
  in 
  all 
  stages 
  of 
  growth 
  situated 
  at 
  

   the 
  posterior 
  end. 
  Nuclei 
  in 
  synizesis 
  may 
  be 
  found 
  in 
  the 
  ovaries 
  of 
  the 
  

  

  