﻿564 
  J. 
  B. 
  FARMER 
  AND 
  D. 
  SHOVE. 
  

  

  If 
  tliey 
  are 
  really 
  present 
  they 
  must 
  increase 
  greatly 
  in 
  

   length, 
  or 
  else 
  the 
  coiling 
  of 
  the 
  filaments 
  now 
  proceeding 
  

   must 
  be 
  attended 
  by 
  end-to-end 
  fusion 
  (fig. 
  7). 
  

  

  During 
  the 
  prophase 
  of 
  this 
  mitosis 
  two 
  ''contraction" 
  

   figures 
  maybe 
  recognised; 
  the 
  first, 
  appearing 
  as 
  the 
  fibrillar 
  

   arrangement, 
  seems 
  to 
  give 
  way 
  to 
  a 
  more 
  filamentous 
  

   structure. 
  Possibly 
  the 
  two 
  circumstances 
  may 
  b'c 
  in 
  some 
  

   way 
  related, 
  but 
  at 
  any 
  rate 
  after 
  the 
  contraction 
  passes 
  

   away 
  the 
  chromatin 
  appears 
  as 
  a 
  much 
  coiled 
  filament, 
  while 
  

   there 
  is 
  a 
  clear 
  alternation 
  of 
  stainable 
  and 
  non-stainable 
  

   discs, 
  as 
  noted 
  long 
  ago 
  by 
  Strasburger 
  and 
  others. 
  The 
  

   stainable 
  (chromatic) 
  discs 
  divide 
  in 
  such 
  a 
  manner 
  as 
  to 
  

   bring 
  about 
  the 
  fission 
  of 
  the 
  thread, 
  though 
  the 
  two 
  halves 
  

   do 
  not, 
  during 
  prophase, 
  divaricate 
  much 
  from 
  each 
  other. 
  

  

  A 
  second, 
  poiut 
  is 
  easily 
  established 
  with 
  respect 
  to 
  the 
  

   filament 
  after 
  the 
  first 
  contraction 
  is 
  over; 
  the 
  coils, 
  into 
  

   which 
  it 
  is 
  thrown, 
  become 
  very 
  strongly 
  polarised. 
  Indeed, 
  

   the 
  effect 
  is 
  nearly 
  as 
  striking 
  as 
  in 
  the 
  case 
  of 
  animals 
  

   (figs. 
  30 
  — 
  34). 
  The 
  loops 
  thus 
  formed 
  and 
  spread 
  out 
  can 
  

   be 
  easily 
  examined, 
  and 
  they 
  are 
  clearly 
  seen 
  to 
  be 
  split 
  

   longitudinally. 
  This 
  early 
  longitudinal 
  fission 
  is 
  of 
  some 
  

   importance, 
  because 
  it 
  has 
  often 
  been 
  regarded, 
  as 
  diagnostic 
  

   of 
  the 
  heterotype 
  mitosis, 
  but, 
  as 
  we 
  have 
  already 
  seen 
  it 
  to 
  

   be 
  present 
  during 
  the 
  earlier 
  stages 
  of 
  the 
  somatic 
  division, 
  

   it 
  is 
  obvious 
  that 
  this 
  criterion, 
  as 
  a 
  means 
  of 
  diagnosis, 
  

   breaks 
  down. 
  

  

  The 
  polarisation 
  of 
  the 
  spireme 
  is 
  also 
  common 
  to 
  the 
  

   heterotype 
  and 
  the 
  somatic 
  mitoses, 
  but 
  it 
  does 
  not 
  seem 
  

   possible 
  to 
  correlate 
  the 
  number 
  of 
  loops 
  of 
  the 
  spireme 
  with 
  

   the 
  final 
  number 
  of 
  chromosomes 
  to 
  be 
  produced. 
  The 
  

   polarised 
  appearance, 
  during 
  which 
  the 
  spireme 
  folds 
  lie 
  so 
  

   regularly 
  arranged 
  within 
  the 
  nuclear 
  wall, 
  is, 
  however, 
  a 
  

   transient 
  phase. 
  A 
  second 
  contraction 
  of 
  the 
  thread 
  follows 
  

   it, 
  and 
  results 
  in 
  the 
  balling 
  together 
  of 
  the 
  filament 
  to 
  one 
  

   end 
  of 
  the 
  nucleus, 
  usually 
  around 
  the 
  nucleolus. 
  Whilst 
  in 
  

   this 
  state 
  (figs. 
  34 
  and 
  35) 
  the 
  longitudinal 
  fission 
  can 
  still 
  

   be 
  seen, 
  though 
  it 
  is 
  becoming 
  for 
  the 
  most 
  part 
  obliterated 
  

  

  