﻿SPERMATOGENISIS 
  OF 
  PERIPLANETA 
  AMERICANA. 
  575 
  

  

  meridional 
  bands 
  of 
  linin 
  which 
  are 
  densely 
  infiltrated 
  with 
  

   chromatin 
  granules 
  (fig. 
  9). 
  

  

  This 
  alteration 
  in 
  the 
  disposition 
  of 
  the 
  chromatin 
  also 
  

   affects 
  the 
  nucleolus. 
  This 
  body, 
  being 
  supported 
  in 
  the 
  

   linin 
  substance, 
  becomes 
  pulled 
  out, 
  at 
  the 
  time 
  of 
  the 
  

   polarisation 
  of 
  the 
  reticulum, 
  into 
  an 
  elongated 
  pear-shape 
  

   (fig. 
  9). 
  The 
  elongated 
  nucleolus 
  at 
  this 
  stage 
  often 
  comes 
  

   to 
  lie 
  in 
  contact 
  with 
  one 
  of 
  the 
  chromatic 
  bands, 
  and, 
  as 
  

   these 
  bands 
  shorten 
  and 
  thicken 
  in 
  the 
  contraction 
  of 
  the 
  

   nuclear 
  contents, 
  the 
  nucleolus 
  often 
  closely 
  simulates 
  the 
  latter 
  

   in 
  appearance 
  (fig. 
  10). 
  Shortly 
  after 
  the 
  appearance 
  of 
  

   polarity, 
  the 
  nuclear 
  contents 
  contract 
  away 
  from 
  the 
  nuclear 
  

   membrane, 
  which 
  becomes 
  ill-defined, 
  and 
  it 
  is 
  then 
  seen 
  

   that 
  the 
  chromatin 
  is 
  arranged 
  in 
  a 
  system 
  of 
  loops, 
  sixteen 
  

   in 
  number, 
  whose 
  tapering, 
  free 
  extremities 
  are 
  gathered 
  

   together 
  at 
  that 
  portion 
  of 
  the 
  periphery 
  of 
  the 
  nucleus 
  

   adjacent 
  to 
  the 
  archoplasm 
  (figs. 
  10, 
  11). 
  This 
  constitutes 
  

   the 
  first 
  synaptic 
  contraction 
  of 
  the 
  heterotype 
  prophase. 
  

  

  As 
  the 
  loops 
  of 
  chromatin 
  contract 
  the 
  nucleolus 
  also 
  

   becomes 
  shorter 
  and 
  thicker, 
  the 
  extremity 
  remote 
  from 
  the 
  

   archoplasm 
  assuming 
  the 
  appearance 
  of 
  a 
  dense 
  blot 
  on 
  the 
  

   surface 
  of 
  the 
  nucleus 
  (fig. 
  11). 
  The 
  loops 
  of 
  chromatin 
  now 
  

   begin 
  to 
  lengthen 
  out 
  so 
  as 
  to 
  extend 
  over 
  the 
  periphery 
  of 
  

   the 
  nuclear 
  space, 
  and 
  this 
  takes 
  place 
  to 
  such 
  an 
  extent 
  

   that 
  the 
  appearance 
  of 
  polarity 
  is 
  lost. 
  During 
  this 
  latter 
  

   phase 
  the 
  long 
  attenuated 
  " 
  tail 
  " 
  of 
  the 
  nucleolus 
  is 
  retracted, 
  

   and 
  the 
  nucleolus 
  assumes 
  a 
  spherical 
  form, 
  and 
  apparently 
  

   lies 
  freely 
  suspended 
  in 
  the 
  nuclear 
  sap 
  among 
  the 
  skein-like 
  

   mass 
  of 
  chromatin 
  bands 
  (fig. 
  12). 
  

  

  It 
  remains 
  quiescent 
  in 
  this 
  condition 
  throughout 
  the 
  

   following 
  heterotype 
  prophases, 
  until 
  the 
  chromatic 
  loops 
  

   again 
  contract 
  towards 
  the 
  nuclear 
  membrane 
  at 
  the 
  point 
  

   adjacent 
  to 
  the 
  archoplasm 
  (fig. 
  14). 
  The 
  nucleolus 
  then 
  

   undergoes 
  fragmentation, 
  giving 
  rise 
  to 
  a 
  number 
  of 
  small, 
  

   highly 
  -refractive, 
  chromatic 
  bodies, 
  lying 
  entangled 
  in 
  the 
  

   bunch 
  of 
  contracted 
  loops. 
  

  

  The 
  heterotype 
  spindle 
  appears 
  about 
  this 
  time 
  as 
  a 
  

  

  