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  Mr. 
  L. 
  T. 
  Hogben. 
  

  

  Marshall 
  (1907), 
  that 
  all 
  three 
  cell 
  elements 
  in 
  the 
  ovarioles 
  of 
  this 
  group 
  — 
  

   nurse 
  cells, 
  oocytes, 
  and 
  epithelia 
  — 
  arise 
  equally 
  from 
  the 
  differentiation 
  of 
  

   germ 
  cells. 
  For 
  two 
  reasons, 
  then, 
  the 
  nitotic 
  figures 
  in 
  the 
  follicular 
  cells 
  of 
  

   Bhodites 
  demand 
  special 
  consideration, 
  as 
  indicating 
  the 
  true 
  diploid 
  number 
  

   of 
  chromosomes 
  : 
  (i) 
  in 
  the 
  allied 
  Cynipid 
  genus 
  Neuroterus, 
  according 
  to 
  

   Doncaster, 
  dividing 
  follicle 
  cells 
  give 
  the 
  same 
  count 
  as 
  dividing 
  oogonia, 
  and 
  1 
  , 
  

   the 
  same 
  is 
  seen 
  in 
  my 
  own 
  preparations 
  of 
  Cynips, 
  set 
  forth 
  above 
  ; 
  (ii) 
  in 
  

   origin 
  they 
  are 
  germinal. 
  I 
  have 
  figured 
  a 
  particularly 
  clear 
  anaphase 
  of 
  a-, 
  

   dividing 
  follicle 
  cell 
  showing 
  18 
  chromosomes 
  at 
  one 
  pole, 
  and 
  this 
  avoids; 
  

   any 
  suspicion 
  that 
  both 
  sets 
  of 
  chromosomes 
  have 
  been 
  counted 
  in 
  an 
  

   equatorial 
  plate 
  ; 
  some 
  stress 
  is 
  laid 
  upon 
  this, 
  since 
  Henking's 
  count 
  of 
  the: 
  

   segmentation 
  mitoses 
  is 
  almost 
  twice 
  that 
  of 
  Schleip 
  (Plate 
  5, 
  fig. 
  18). 
  

  

  The 
  Synaptic 
  Phase. 
  

  

  In 
  the 
  full-grown 
  larvae 
  at 
  the 
  end 
  of 
  the 
  first 
  season 
  the 
  ovaries 
  are- 
  

   inconspicuous 
  ovoid 
  masses 
  of 
  cells 
  with 
  granular 
  nuclei. 
  The 
  ovary 
  is- 
  

   surrounded 
  by 
  a 
  capsule 
  of 
  connective 
  tissue, 
  and 
  its 
  component 
  cells 
  are 
  

   undifferentiated. 
  As 
  in 
  the 
  case 
  of 
  Cynips, 
  the 
  fact 
  that 
  mitoses 
  do 
  not 
  

   normally 
  occur 
  at 
  this 
  stage 
  suggests 
  that 
  the 
  ovaries 
  are 
  formed 
  early 
  and 
  

   pass 
  temporarily 
  through 
  a 
  period 
  of 
  rest, 
  during 
  which 
  there 
  is 
  no 
  cell 
  

   division. 
  In 
  the 
  following 
  spring 
  (and 
  sometimes 
  in 
  the 
  autumn 
  of 
  the 
  first 
  

   season) 
  changes 
  begin 
  to 
  occur. 
  Oogonia 
  begin 
  to 
  divide 
  into 
  rosettes 
  

   (fig. 
  20). 
  The 
  cells 
  of 
  a 
  rosette 
  divide 
  synchronously, 
  as 
  in 
  Apis. 
  

  

  Some 
  25 
  clear 
  anaphase 
  plates 
  at 
  this 
  stage 
  were 
  observed, 
  in 
  which 
  

   it 
  was 
  possible 
  to 
  count 
  the 
  chromosomes 
  without 
  difficulty, 
  the 
  number 
  being- 
  

   the 
  same 
  — 
  18 
  — 
  as 
  that 
  in 
  the 
  dividing 
  follicle 
  cells 
  (fig. 
  19). 
  This 
  conclu- 
  

   sively 
  vindicates 
  Henking's 
  assertion 
  regarding 
  the 
  somatic 
  number 
  in 
  

   Bhodites* 
  In 
  early 
  stages 
  of 
  ovaries 
  at 
  the 
  inception 
  of 
  differentiation 
  it 
  is- 
  

   possible 
  to 
  distinguish 
  three 
  regions 
  : 
  (a) 
  zone 
  of 
  rosettes 
  ; 
  (5) 
  zone 
  of 
  

   undifferentiated 
  oogonia; 
  (c) 
  zone 
  of 
  flattened 
  apparently 
  vacuolated 
  cells,, 
  

   which 
  correspond 
  to 
  those 
  which 
  are 
  found 
  in 
  the 
  terminal 
  filaments 
  of 
  the 
  

   ovarioles 
  of 
  young 
  pupae. 
  With 
  the 
  exception 
  of 
  the 
  last, 
  all 
  cells 
  rapidly 
  

  

  * 
  I 
  find 
  that 
  several 
  writers 
  who 
  have 
  accepted 
  Schleip's 
  observations, 
  including 
  

   Miss 
  Harvey 
  and 
  Cutler, 
  states 
  that 
  he 
  gives 
  10-12 
  as 
  the 
  number 
  of 
  chromosomes 
  

   in 
  the 
  dividing 
  oogonia. 
  It 
  is 
  true 
  that 
  he 
  says, 
  in 
  describing 
  the 
  segmentation 
  

   divisions, 
  " 
  der 
  normale 
  Chromosomenzahl 
  bei 
  Rkodites 
  rosce 
  ist 
  also 
  etwas 
  12 
  ; 
  die 
  

   gleiche 
  Zahl 
  miissen 
  wir 
  auch 
  in 
  den 
  Oogonien 
  annehmen 
  " 
  ; 
  but 
  nowhere 
  does 
  he 
  

   refer 
  to 
  preparations 
  or 
  give 
  illustrations 
  of 
  oogonial 
  mitoses 
  — 
  on 
  the 
  contrary 
  he 
  

   expressly 
  asserts 
  (erroneously), 
  "die 
  Zahl 
  der 
  Chromosomen 
  in 
  den 
  Ureizellen 
  ist 
  nicht. 
  

   zu 
  bestimmen." 
  

  

  