﻿Studies 
  on 
  Synapsis. 
  

  

  281 
  

  

  pole 
  of 
  the 
  egg 
  in 
  the 
  blackberry 
  knot 
  gall-fly, 
  Diastrophus. 
  Since 
  the 
  fate 
  

   of 
  the 
  " 
  germ-cell 
  determinant 
  " 
  has 
  only 
  been 
  worked 
  out 
  in 
  a 
  few 
  cases, 
  it 
  

   would 
  appear 
  advisable 
  to 
  adopt 
  for 
  the 
  present 
  Silvestri's 
  newly 
  proposed 
  

   term 
  " 
  oosoma," 
  or 
  if 
  the 
  rule 
  as 
  to 
  precedence 
  is 
  rigidly 
  enforced, 
  alterna- 
  

   tively, 
  let 
  it 
  be 
  still 
  called 
  the 
  " 
  polar 
  disc." 
  This 
  would 
  obviate 
  the 
  

   drawback 
  of 
  being 
  committed 
  to 
  any 
  particular 
  theory 
  as 
  to 
  its 
  physiological 
  

   or 
  genetic 
  significance 
  in 
  the 
  developmental 
  process. 
  

  

  The 
  Secondary 
  Nuclei. 
  

  

  Gatenby 
  (1918) 
  has 
  noticed 
  in 
  the 
  egg 
  of 
  Trichogramma 
  the 
  presence 
  of 
  

   " 
  large 
  spherical 
  granules 
  " 
  staining 
  deeply 
  with 
  iron 
  hseniatoxylin. 
  They 
  

   were 
  also 
  found 
  in 
  Cynips 
  and 
  smaller 
  and 
  more 
  numerous 
  bodies 
  of 
  similar 
  

   origin 
  in 
  Rhodites, 
  where 
  they 
  have 
  been 
  shown 
  to 
  be 
  of 
  nuclear 
  origin, 
  their 
  

   appearance 
  being 
  correlated 
  with 
  the 
  diminution 
  of 
  staining 
  capacity 
  

   exhibited 
  by 
  the 
  nucleus 
  during 
  the 
  growth 
  period. 
  Such 
  granules 
  are 
  found 
  

   at 
  all 
  stages 
  after 
  synapsis 
  in 
  Synergus. 
  In 
  the 
  full 
  grown 
  egg 
  little 
  

   groups 
  of 
  granules 
  are 
  sometimes 
  recognised 
  in 
  the 
  peripheral 
  region 
  ; 
  these 
  

   appear 
  to 
  be 
  the 
  result 
  of 
  fragmentation 
  of 
  the 
  larger 
  nucleoli. 
  During 
  the 
  

   growth 
  period 
  the 
  nucleus 
  is 
  seen 
  to 
  contain 
  numerous 
  granules 
  of 
  various 
  

   sizes. 
  

  

  In 
  addition, 
  true 
  secondary 
  nuclei 
  make 
  their 
  appearance 
  in 
  the 
  peri- 
  

   pheral 
  cytoplasm 
  towards 
  the 
  end 
  of 
  the 
  growth 
  period. 
  Such 
  nuclei 
  are 
  

   found 
  in 
  the 
  eggs 
  of 
  aculeate 
  Hymenoptera, 
  but 
  do 
  not 
  occur 
  generally 
  in 
  

   other 
  groups 
  ; 
  the}' 
  have, 
  however, 
  been 
  described 
  by 
  Hegner 
  (1914) 
  in 
  the 
  

   oocytes 
  of 
  the 
  Braconid, 
  Apanteles. 
  Those 
  in 
  Synergus 
  agree 
  remarkably 
  

   closely 
  with 
  the 
  description 
  given 
  for 
  the 
  latter 
  genus. 
  Each 
  has 
  a 
  definite 
  

   membrane 
  and 
  contains 
  a 
  substance 
  staining 
  like 
  chromatin 
  in 
  the 
  form 
  of 
  

   several 
  small 
  masses 
  and 
  a 
  few 
  strands 
  of 
  granules. 
  That 
  they 
  arise 
  de 
  novo, 
  

   that 
  is 
  to 
  say, 
  they 
  do 
  not 
  originate 
  by 
  the 
  division 
  of 
  pre-existing 
  nuclei, 
  is 
  

   agreed 
  by 
  Hegner 
  as 
  regards 
  Apanteles 
  and 
  shown 
  in 
  Synergus 
  by: 
  (1) 
  the 
  

   absolutely 
  constant 
  form 
  of 
  the 
  germinal 
  vesicle 
  at 
  the 
  time 
  when 
  they 
  

   appear 
  precludes 
  any 
  possibility 
  that 
  they 
  arise 
  by 
  budding 
  from 
  it 
  ; 
  (2) 
  the 
  

   complete 
  isolation 
  of 
  the 
  oocyte 
  by 
  its 
  follicle 
  at 
  the 
  time 
  when 
  secondary 
  

   nuclei 
  are 
  first 
  seen 
  excludes 
  any 
  possibility 
  that 
  they 
  are 
  derived 
  from 
  

   nuclei 
  other 
  than 
  those 
  of 
  the 
  follicle 
  cells 
  ; 
  (3) 
  careful 
  examination 
  of 
  the 
  

   follicle 
  cells 
  and 
  their 
  nuclei 
  at 
  this 
  stage 
  makes 
  it 
  extremely 
  improbable 
  that 
  

   there 
  is 
  any 
  migration 
  of 
  nuclei 
  from 
  the 
  epithelium 
  into 
  the 
  peripheral 
  

   cytoplasm 
  of 
  the 
  egg. 
  Beyond 
  this, 
  Hegner 
  makes 
  no 
  suggestions 
  as 
  to 
  their 
  

   presence 
  ; 
  but 
  it 
  seems 
  to 
  me 
  clear 
  that 
  in 
  Synergus 
  they 
  arise 
  from 
  the 
  

   groups 
  of 
  granules 
  in 
  the 
  periphery 
  that 
  have 
  been 
  referred 
  to 
  above. 
  The 
  

  

  