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  Mr. 
  L. 
  T. 
  Hogben. 
  

  

  single 
  X-chromosome 
  and 
  femaleness 
  with 
  a 
  pair 
  ; 
  as, 
  however, 
  there 
  are 
  no 
  

   visible 
  cytological 
  peculiarities 
  in 
  these 
  hypothetical 
  X-chromosomes, 
  and 
  

   since 
  moreover 
  the 
  question 
  of 
  sex-limited 
  inheritance 
  in 
  the 
  Hymenoptera 
  is 
  

   a 
  subject 
  which 
  has 
  not 
  hitherto 
  been 
  investigated 
  to 
  my 
  knowledge, 
  it 
  is 
  only 
  

   possible 
  to 
  accept 
  JSTachtsheim's 
  suggestion 
  with 
  some 
  reservation. 
  

  

  3. 
  Synergus 
  Rheinhardii. 
  

   In 
  rearing 
  Cynips 
  a 
  large 
  number 
  of 
  individuals 
  of 
  Synergus 
  rheinhardii 
  

   and 
  the 
  smaller 
  allied 
  species 
  S. 
  melanopus 
  emerged 
  from 
  the 
  galls 
  in 
  which 
  

   they 
  pass 
  their 
  larval 
  and 
  pupal 
  phases 
  as 
  inquilines. 
  A 
  study 
  of 
  the 
  eggs 
  

   of 
  the 
  inquiline 
  Synergus 
  rheinhardii 
  revealed 
  certain 
  points 
  and 
  led 
  to 
  con- 
  

   clusions 
  which 
  seem 
  to 
  merit 
  record. 
  

  

  The 
  Oosoma. 
  

  

  In 
  several 
  respects 
  the 
  egg 
  of 
  Synergus 
  resembles 
  closely 
  that 
  of 
  Tricho- 
  

   gramma 
  and 
  Copidosoma. 
  Like 
  these 
  it 
  possesses 
  when 
  it 
  has 
  attained 
  its 
  

   full 
  size 
  a 
  well 
  defined 
  body 
  at 
  the 
  posterior 
  pole 
  staining 
  deeply 
  with 
  

   chromatin 
  dyes. 
  This 
  corresponds 
  to 
  what 
  Silvestri 
  originally 
  called 
  the 
  

   " 
  nucleolo," 
  and 
  Hegner 
  the 
  " 
  Keimbahn 
  " 
  or 
  " 
  germ-cell 
  determinants." 
  

   Both 
  of 
  these 
  authors 
  originally 
  believed 
  that 
  it 
  arose 
  from 
  nuclear 
  material. 
  

   In 
  view 
  of 
  its 
  subsequent 
  distribution 
  in 
  certain 
  forms 
  among 
  the 
  germ 
  cells 
  

   this 
  view 
  is 
  a 
  tempting 
  one 
  to 
  those 
  who 
  advocate 
  the 
  doctrines 
  of 
  Weismann 
  

   in 
  their 
  extreme 
  form 
  ; 
  but 
  it 
  has 
  been 
  shown 
  by 
  Gatenby 
  in 
  Trichogramma, 
  

   Martin 
  in 
  Ageniaspis, 
  and 
  since 
  reported 
  by 
  Hegner 
  and 
  Silvestri 
  in 
  Copido- 
  

   soma 
  that 
  it 
  is 
  derived 
  from 
  the 
  cytoplasm. 
  In 
  Synergus 
  as 
  in 
  Trichogramma, 
  

   the 
  " 
  germ-cell 
  determinant 
  " 
  arises 
  " 
  as 
  a 
  cloud 
  of 
  granules 
  which 
  make 
  

   their 
  appearance 
  spontaneously 
  in 
  the 
  cytoplasm 
  . 
  . 
  . 
  become 
  more 
  and 
  more 
  

   heavily 
  staining 
  and 
  denser 
  until 
  the 
  determinant 
  resembles 
  a 
  spherical 
  ball 
  

   at 
  the 
  end 
  of 
  the 
  egg 
  " 
  (figs. 
  39-41). 
  Further, 
  in 
  Synergus 
  as 
  in 
  Tricho- 
  

   gramma, 
  the 
  reaction 
  of 
  this 
  body 
  with 
  respect 
  to 
  G-ilson, 
  Petrunkevvitsch, 
  

   Hemming, 
  and 
  other 
  acetic 
  fixatives 
  employed 
  shows 
  that 
  it 
  is 
  neither 
  

   wholly 
  nor 
  partially 
  of 
  mitochondrial 
  matter 
  as 
  Martin 
  believed. 
  The 
  fact 
  that 
  

   the 
  " 
  germ-cell 
  determinant 
  " 
  is 
  a 
  cytoplasmic 
  inclusion 
  provides 
  confirma- 
  

   tion 
  of 
  the 
  view 
  of 
  organ-forming 
  areas 
  in 
  the 
  cytoplasm 
  of 
  the 
  egg. 
  

   Gatenby 
  has 
  suggested 
  that 
  the 
  function 
  of 
  the 
  determinant 
  is 
  nutritive, 
  

   preventing 
  the 
  germ-cell 
  nuclei 
  from 
  being 
  exposed 
  to 
  the 
  uncertain 
  con- 
  

   ditions 
  existing 
  elsewhere 
  in 
  the 
  segmenting 
  egg 
  and 
  embryo. 
  This 
  might 
  

   be 
  correlated 
  with 
  its 
  more 
  frequent 
  occurrence 
  in 
  parasitic 
  forms. 
  Such 
  

   bodies 
  do 
  not 
  occur 
  in 
  many 
  gallmaking 
  Cynipids, 
  egg 
  Neuroterus, 
  Cynips, 
  

   and 
  Andricus 
  : 
  there 
  is, 
  however, 
  a 
  well 
  defined 
  structure 
  at 
  the 
  posterior 
  

  

  