﻿518 
  J. 
  BRETLAND 
  FARMER 
  AND 
  J. 
  E. 
  S. 
  MOORE. 
  

  

  in 
  support 
  of 
  his 
  views, 
  but 
  we 
  have 
  ah-eady 
  expressed 
  our 
  

   reasons 
  for 
  regarding 
  them 
  as 
  inadequate 
  to 
  afford 
  a 
  com- 
  

   plete 
  picture 
  of 
  the 
  whole 
  series 
  of 
  changes. 
  

  

  The 
  main 
  points 
  of 
  difference 
  between 
  us 
  are 
  these 
  : 
  

  

  1. 
  M. 
  Gregoire 
  considers 
  that 
  during 
  (?) 
  the 
  "synaptic" 
  

   (1st) 
  contraction 
  a 
  lateral 
  approximation 
  of 
  thin 
  spireme 
  

   thread 
  occurs, 
  and 
  that 
  this 
  then 
  fuses. 
  Our 
  view 
  is 
  the 
  

   reverse 
  of 
  this. 
  

  

  2. 
  The 
  closed, 
  jointed 
  threads 
  next 
  split 
  asunder, 
  and 
  the 
  

   doubled 
  segments 
  of 
  the 
  spireme 
  thus 
  formed 
  give 
  rise 
  to 
  

   the 
  definitive 
  chromosomes, 
  with 
  their 
  variously 
  twisted 
  

   limbs. 
  We 
  regard 
  the 
  original 
  longitudinal 
  fission 
  as 
  

   temporarily 
  closing 
  ; 
  this 
  is 
  followed 
  by 
  an 
  approximation 
  of 
  

   the 
  thread 
  into 
  parallel 
  lines, 
  whether 
  this 
  is 
  formed 
  by 
  loop- 
  

   ing 
  or 
  otherwise. 
  At 
  this 
  stage 
  the 
  second 
  contraction 
  figure 
  

   is 
  intercalated. 
  We 
  find 
  traces 
  of 
  the 
  longitudinal 
  fission 
  to 
  

   occur 
  in 
  the 
  collateral 
  threads 
  from 
  the 
  first, 
  whilst 
  Grregoire 
  

   does 
  not 
  admit 
  its 
  existence 
  till 
  after 
  the 
  chromosomes 
  are 
  

   arranged 
  in 
  the 
  spindle. 
  

  

  M. 
  Gregoire 
  is 
  in 
  agreement 
  with 
  us 
  in 
  regarding 
  each 
  

   chromosome 
  as 
  a 
  bivalent 
  structure, 
  and 
  as 
  equivalent 
  to 
  two 
  

   somatic 
  chromosomes 
  lying 
  in 
  close 
  juxtaposition 
  or 
  even 
  

   partially 
  united 
  ; 
  and 
  further, 
  that 
  during 
  the 
  heterotype 
  

   mitosis 
  a 
  distribution 
  of 
  entire 
  somatic 
  chromosomes 
  takes 
  

   place. 
  

  

  II. 
  Osmunda 
  regalis. 
  

  

  The 
  ai'chesporial 
  cells 
  in 
  the 
  sporangium 
  are 
  characteristic 
  

   in 
  their 
  appearance. 
  The 
  cells 
  are 
  large 
  and 
  somewhat 
  

   oblong, 
  and 
  the 
  very 
  prominent 
  nucleus 
  is 
  commonly 
  placed 
  

   excentrically, 
  being 
  nearer 
  one 
  end 
  of 
  the 
  cell 
  than 
  the 
  other. 
  

  

  The 
  nucleus 
  possesses 
  a 
  well-defined 
  wall, 
  and 
  contains 
  a 
  

   nucleolus. 
  The 
  chromatin 
  can 
  certainly, 
  at 
  least 
  in 
  the 
  early 
  

   stages, 
  be 
  said 
  to 
  exist 
  in 
  such 
  an 
  arrangement 
  as 
  to 
  suggest 
  

   a 
  spireme. 
  Sometimes 
  the 
  granules 
  of 
  chromatin 
  appear 
  to 
  

   be 
  scattered 
  irregularly, 
  so 
  as 
  to 
  give 
  the 
  impression 
  that 
  

   one 
  is 
  confronted 
  by 
  a 
  foam 
  structure, 
  the 
  granules 
  lying 
  

  

  