﻿THE 
  MAIOTIO 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  533 
  

  

  ceutrosomes 
  can 
  be 
  first 
  discerned 
  in 
  the 
  cytoplasm 
  opposite 
  

   the 
  ends 
  of 
  the 
  emerging 
  chromatic 
  loops. 
  

  

  From 
  the 
  time 
  at 
  which 
  these 
  maiotic 
  cells 
  can 
  be 
  first 
  

   distinguished 
  they 
  present 
  — 
  unlike 
  the 
  pre-maiotic 
  elements 
  

   which 
  have 
  anteceded 
  them 
  — 
  a 
  single, 
  distinct, 
  and 
  relatively 
  

   large 
  nucleolus 
  ; 
  and 
  during 
  the 
  onset 
  of 
  the 
  synaptic 
  phase 
  

   this 
  body 
  becomes 
  stretched 
  out 
  and 
  lengthened 
  as 
  the 
  

   polarization 
  of 
  the 
  nucleus 
  increases, 
  so 
  that 
  eventually 
  it 
  

   pi'oduces 
  a 
  curious 
  and 
  characteristic 
  appearance 
  represented 
  

   in 
  figs. 
  53-56. 
  

  

  In 
  the 
  succeeding 
  phases 
  the 
  polarisation 
  of 
  the 
  chromatic 
  

   loops 
  becomes 
  at 
  first 
  more 
  complete. 
  Or, 
  in 
  other 
  words, 
  the 
  

   original 
  chromatic 
  meshwork 
  becomes 
  more 
  and 
  more 
  

   definitely 
  drawn 
  out 
  into 
  the 
  broad, 
  horseshoe-like 
  struc- 
  

   tures 
  which 
  are 
  represented 
  in 
  figs. 
  57—58. 
  At 
  the 
  same 
  time 
  

   the 
  whole 
  chromatic 
  substance 
  of 
  the 
  nucleus 
  tends 
  -to 
  con- 
  

   tract 
  away 
  from 
  the 
  nuclear 
  membrane 
  towards 
  the 
  sphere 
  

   (archoplasm). 
  It 
  is 
  this 
  first 
  contraction 
  figure 
  which 
  has 
  often 
  

   been 
  spoken 
  of 
  as 
  the 
  synaptic 
  contraction, 
  but 
  as 
  a 
  matter 
  

   of 
  fact 
  there 
  are 
  in 
  reality 
  two 
  contraction 
  stages, 
  of 
  which 
  the 
  

   figures 
  represented 
  in 
  figs. 
  53-67, 
  only 
  illustrate 
  the 
  first. 
  

  

  When 
  the 
  chromatic 
  loops 
  have 
  acquired 
  the 
  definite 
  

   characters 
  delineated 
  in 
  fig. 
  57, 
  they 
  begin 
  to 
  open 
  out 
  

   over 
  the 
  surface 
  of 
  the 
  nucleus, 
  and 
  often 
  become 
  actually 
  

   thinner, 
  until 
  figures 
  like 
  those 
  represented 
  in 
  figs. 
  63-66 
  

   are 
  frequently 
  obtained. 
  The 
  process 
  of 
  unravelling, 
  however, 
  

   continues 
  still 
  farther 
  than 
  this, 
  until 
  the 
  nucleus 
  presents 
  a 
  

   typical 
  co;irse 
  spireme 
  irregularly 
  distributed 
  over 
  its 
  surface 
  

   as 
  is 
  shown 
  in 
  fig. 
  QQ. 
  

  

  At 
  about 
  this 
  stage 
  in 
  the 
  cockroach 
  it 
  is 
  generally 
  possible 
  

   to 
  observe 
  that 
  the 
  nuclear 
  threadwork 
  is 
  becoming 
  longi- 
  

   tudinally 
  split, 
  and 
  the 
  appearance 
  which 
  the 
  cells 
  then 
  

   present 
  is 
  reproduced 
  in 
  fig. 
  67, 
  the 
  Avhole 
  of 
  this 
  phase 
  

   of 
  the 
  division 
  reaching 
  its 
  maximum 
  in 
  such 
  elements 
  as 
  

   have 
  been 
  represented 
  in 
  figs. 
  64-67. 
  In 
  all 
  these 
  later 
  

   figures 
  the 
  cells 
  present 
  the 
  coarse 
  spirem 
  appearance 
  which 
  

   is 
  so 
  well 
  known. 
  However, 
  it 
  is 
  not 
  in 
  this 
  stage 
  that 
  the 
  

  

  