﻿510 
  J. 
  BRETLAND 
  PARMER 
  AND 
  J. 
  E. 
  S. 
  MOORE. 
  

  

  then 
  they 
  are 
  seen 
  to 
  be 
  furrowed 
  and 
  to 
  assume 
  a 
  dumb-bell- 
  

   shaped 
  appearance. 
  Finally 
  the 
  halves 
  of 
  each 
  bead 
  separate 
  

   from 
  one 
  another 
  and 
  come 
  to 
  lie 
  in 
  two 
  parallel 
  rows 
  at 
  the 
  

   edges 
  of 
  the 
  flattened 
  spireme 
  ribbon. 
  

  

  The 
  ribbon 
  itself 
  next 
  splits 
  longitudinally. 
  The 
  fission 
  is 
  

   irregular, 
  especially 
  at 
  first, 
  and 
  it 
  merely 
  forms 
  open 
  loops, 
  

   closed 
  at 
  either 
  end 
  where 
  the 
  ribbon 
  has 
  not 
  yet 
  split. 
  But 
  

   later 
  on 
  it 
  becomes 
  much 
  more 
  complete 
  and 
  the 
  halves 
  

   proceed 
  to 
  divaricate 
  (Fig. 
  5) 
  more 
  or 
  less 
  considerably 
  from 
  

   each 
  other. 
  This 
  fission 
  has 
  been 
  more 
  or 
  less 
  clearly 
  recog- 
  

   nised 
  as 
  such 
  by 
  most 
  writers 
  who 
  have 
  investigated 
  lilies, 
  with 
  

   the 
  exception 
  of 
  Dixon, 
  who 
  i-egarded 
  the 
  appearance 
  as 
  due 
  

   to 
  an 
  approximation 
  of 
  originally 
  separate 
  filaments. 
  In 
  the 
  

   lilies 
  the 
  result 
  of 
  fission 
  is 
  much 
  more 
  marked 
  than 
  in 
  tlie 
  

   majority 
  of 
  other 
  plants 
  studied 
  by 
  us. 
  It 
  is 
  doubtless 
  to 
  

   this 
  circumstance 
  that 
  the 
  prevalent 
  misconception 
  as 
  to 
  the 
  

   true 
  nature 
  of 
  the 
  succeeding 
  changes 
  is 
  due, 
  and 
  it 
  serves 
  to 
  

   emphasise 
  the 
  necessity 
  of 
  comparative 
  study 
  as 
  opposed 
  to 
  

   an 
  undue 
  reliance 
  on 
  the 
  results 
  of 
  investigations 
  made 
  on 
  

   single 
  types, 
  however 
  promising 
  these 
  may 
  individually 
  seem 
  

   to 
  be. 
  Thus 
  a 
  comparison 
  of 
  the 
  processess 
  as 
  they 
  are 
  

   manifested 
  in 
  the 
  lily 
  with 
  those 
  corresponding 
  to 
  them 
  in 
  

   the 
  Osmunda, 
  Tradescantia, 
  or 
  Aneura, 
  at 
  once 
  throws 
  

   light 
  on 
  the 
  actual 
  sequence 
  of 
  events, 
  though 
  the 
  investi- 
  

   gation 
  in 
  no 
  case 
  is 
  an 
  easy 
  one. 
  But 
  the 
  evidence 
  is 
  quite 
  

   decisive, 
  and 
  indicates 
  re-approximation 
  of 
  the 
  separated 
  

   halves 
  of 
  the 
  ribbon. 
  Thus 
  the 
  split 
  gradually 
  closes 
  up 
  

   again 
  (Figs. 
  7-11) 
  and 
  may 
  be 
  so 
  nearly 
  obliterated 
  as 
  to 
  

   become 
  very 
  difficult 
  to 
  recognise. 
  At 
  the 
  same 
  time 
  the 
  

   thread 
  is 
  shortening 
  and 
  thickening, 
  whilst 
  the 
  polarisation 
  

   already 
  alluded 
  to 
  may 
  be 
  more 
  easily 
  seen. 
  The 
  thread, 
  in 
  

   many 
  of 
  its 
  convolutions, 
  is 
  attached 
  rather 
  securely 
  to 
  the 
  

   nuclear 
  wall, 
  whilst 
  the 
  rest 
  becomes 
  aggregated 
  into 
  a 
  some- 
  

   what 
  dense 
  tangle 
  towards 
  the 
  centre, 
  where 
  the 
  nucleolus 
  is 
  

   now 
  commonly 
  situated. 
  The 
  latter 
  body 
  (there 
  may 
  be 
  one 
  

   or 
  more 
  of 
  them 
  present 
  in 
  each 
  nucleus) 
  is 
  vacuolated 
  and 
  

   has 
  clearly 
  lost 
  much 
  of 
  its 
  substance. 
  This 
  has 
  been 
  utilised 
  

  

  