﻿578 
  J. 
  E. 
  S. 
  MOORE 
  AND 
  L. 
  E. 
  EOBINSON. 
  

  

  ia 
  contact 
  with 
  the 
  nuclear 
  membrane, 
  the 
  other 
  passes 
  

   inwards 
  to 
  the 
  middle 
  of 
  the 
  nucleus 
  (fig. 
  32) 
  . 
  

  

  The 
  cytoplasm, 
  at 
  this 
  stage, 
  contains 
  a 
  well-marked 
  

   nebenkern, 
  but 
  the 
  remnants 
  of 
  the 
  heterotype 
  nucleolus 
  are 
  

   by 
  this 
  time 
  so 
  altered 
  as 
  to 
  be 
  invisible. 
  

  

  The 
  portion 
  of 
  the 
  spermatid 
  nucleolus 
  which 
  is 
  still 
  in 
  

   contact 
  with 
  the 
  nuclear 
  membrane 
  now 
  passes 
  through, 
  and 
  

   is 
  extruded 
  into 
  the 
  cytoplasm, 
  where 
  it 
  appears 
  as 
  a 
  rounded, 
  

   highly 
  chromatic 
  mass 
  (fig. 
  33), 
  and 
  is 
  subsequently 
  lost 
  sight 
  

   of 
  in 
  the 
  liquor 
  seminis. 
  

  

  The 
  other 
  portion 
  of 
  the 
  nucleolus 
  remains 
  at 
  the 
  centre 
  of 
  

   the 
  nucleus, 
  and 
  undergoes 
  a 
  slow 
  process 
  of 
  degeneration, 
  

   staining 
  more 
  and 
  more 
  feebly 
  until 
  it 
  is 
  finally 
  lost 
  sight 
  of. 
  

   The 
  extra-nuclear 
  portion 
  of 
  the 
  nucleolus 
  sometimes 
  under- 
  

   goes 
  further 
  fragmentation 
  in 
  the 
  cytoplasm 
  (fig. 
  34), 
  but 
  

   such 
  fragments 
  can 
  be 
  readily 
  distinguished 
  from 
  the 
  pale, 
  

   degenerated 
  fragments 
  of 
  the 
  heterotype 
  nucleolus, 
  which 
  

   may 
  still 
  be 
  visible. 
  

  

  Before 
  this 
  stage 
  is 
  reached 
  the 
  centrosomes 
  have 
  not 
  been 
  

   recognised. 
  They 
  probably 
  lie 
  in 
  contact 
  with 
  the 
  nuclear 
  

   membrane 
  throughout 
  the 
  early 
  phases 
  of 
  the 
  metamorphosis 
  

   of 
  the 
  spermatozoon, 
  and, 
  owing 
  to 
  the 
  nature 
  of 
  the 
  nucleus, 
  

   this 
  would 
  explain 
  the 
  fact 
  of 
  their 
  invisibility. 
  

  

  The 
  formation 
  of 
  the 
  cephalic 
  vesicle, 
  the 
  axial 
  filament, 
  

   and 
  the 
  tail 
  of 
  the 
  spermatozoon, 
  and 
  the 
  behaviour 
  of 
  the 
  

   nebenkern 
  in 
  connection 
  with 
  these 
  processes 
  are 
  not 
  yet 
  

   sufficiently 
  elucidated, 
  and 
  will 
  possibly 
  form 
  the 
  subject 
  of 
  a 
  

   future 
  communication. 
  

  

  'ilie 
  cytoplasm 
  of 
  the 
  spermatid, 
  which 
  is 
  not 
  utilised 
  in 
  the 
  

   formation 
  of 
  the 
  spermatozoon, 
  does 
  not 
  collect 
  as 
  a 
  residual 
  

   corpuscle 
  in 
  this 
  insect, 
  but 
  undergoes 
  a 
  process 
  of 
  mucoid 
  

   degeneration 
  in 
  situ. 
  The 
  extra-nuclear 
  portion 
  of 
  the 
  

   nucleolus 
  is 
  not 
  affected 
  by 
  these 
  degenerative 
  changes 
  of 
  its 
  

   surroundings, 
  and 
  large 
  numbers 
  of 
  these 
  chromatic 
  bodies, 
  

   derived 
  from 
  the 
  different 
  spermatids, 
  may 
  be 
  seen 
  among 
  

   clusters 
  of 
  ripe 
  spermatozoa 
  in 
  a 
  ripe 
  tubule 
  of 
  the 
  testis 
  

   floating 
  in 
  the 
  liquor 
  seminis. 
  

  

  