﻿506 
  J. 
  BRETLAND 
  FARMER 
  AND 
  J. 
  E. 
  S. 
  MOORE. 
  

  

  Detailed 
  Description 
  of 
  Typical 
  Examples 
  op 
  Animals 
  and 
  

   Plants 
  Investigated. 
  

  

  I. 
  Lilium 
  Candidum. 
  

  

  The 
  development 
  of 
  the 
  spores 
  in 
  different 
  species 
  of 
  lilies 
  

   has 
  so 
  often 
  served 
  as 
  the 
  subject 
  of 
  investigation 
  that 
  it 
  

   might 
  seem 
  bnt 
  slightly 
  probable 
  that 
  any 
  fact 
  of 
  material 
  

   importance 
  still 
  remained 
  generally 
  unknown. 
  It 
  has 
  already, 
  

   however, 
  been 
  remarked 
  that 
  divergent 
  views 
  as 
  to 
  the 
  course 
  

   of 
  events 
  during 
  the 
  heterotype 
  and 
  homotype 
  mitoses 
  in 
  

   these 
  plants 
  have 
  been 
  advanced, 
  and 
  the 
  matter 
  cannot, 
  there- 
  

   fore, 
  be 
  regarded 
  as 
  yet 
  to 
  be 
  conclusively 
  settled. 
  Whilst 
  

   the 
  majority 
  of 
  observers 
  hold 
  that 
  a 
  longitudinal 
  division 
  of 
  

   the 
  chromosomes 
  obtains 
  in 
  both 
  the 
  homotype 
  and 
  the 
  hetero- 
  

   type 
  mitoses, 
  Schaffner 
  ^ 
  has 
  adduced 
  evidence 
  in 
  support 
  of 
  

   a 
  "reducing" 
  {i.e. 
  transverse) 
  division 
  occurring 
  in 
  the 
  

   heterotype, 
  whilst 
  Dixon 
  ^ 
  has 
  considered 
  that 
  this 
  was 
  

   achieved 
  during 
  the 
  homotype 
  division. 
  

  

  The 
  principal 
  evidence 
  relied 
  on 
  by 
  those 
  who 
  advocated 
  

   the 
  existence 
  of 
  a 
  longitudinal 
  fission 
  in 
  each 
  mitosis 
  has 
  been 
  

   the 
  supposed 
  proof 
  of 
  the 
  existence 
  of 
  a 
  double 
  fission 
  during 
  

   the 
  late 
  prophase 
  stages 
  in 
  the 
  heterotype. 
  The 
  more 
  recent 
  

   work 
  of 
  Gregoire 
  and 
  others 
  appear 
  to 
  show 
  conclusively 
  that 
  

   at 
  any 
  rate 
  the 
  homotype 
  mitosis 
  does 
  not, 
  in 
  lilies, 
  effect 
  a 
  

   transverse 
  separation 
  of 
  chromosomes, 
  but 
  merely 
  consummates 
  

   a 
  longitudinal 
  fission 
  already 
  incepted 
  during 
  the 
  early 
  stages 
  

   of 
  the 
  preceding 
  mitosis. 
  

  

  We 
  have 
  also 
  studied 
  the 
  homotype 
  division 
  in 
  lilies 
  

   afresh 
  ; 
  and 
  whilst 
  in 
  certain 
  points 
  our 
  views 
  diverge 
  from 
  

   those 
  held 
  by 
  most 
  other 
  investigators, 
  we 
  still 
  consider 
  that 
  

   the 
  most 
  important 
  features 
  of 
  this 
  mitosis 
  consist 
  essentially 
  

   in 
  the 
  separation 
  and 
  subsequent 
  distribution 
  to 
  opposite 
  

   poles 
  of 
  equivalent 
  halves 
  of 
  the 
  chromosomes, 
  and 
  that 
  these 
  

   equivalent 
  halves 
  had 
  already 
  been 
  marked 
  out 
  and 
  defined 
  

  

  ' 
  ' 
  Bot. 
  Gazette,' 
  /oc. 
  cit. 
  

   ^ 
  'Proc. 
  Rov. 
  Ir. 
  Acad..' 
  iii. 
  

  

  