﻿THb] 
  MAIOTIC 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  495 
  

  

  of 
  their 
  own, 
  the 
  supposed 
  relation 
  can 
  at 
  best 
  be 
  dynamical, 
  

   depending 
  on 
  the 
  chromosome 
  substance 
  as 
  a 
  whole 
  

   rather 
  than 
  on 
  that 
  of 
  the 
  individual 
  units. 
  No 
  doubt 
  the 
  

   connection 
  of 
  the 
  nuclei 
  with 
  the 
  specific 
  organisation 
  of 
  the 
  

   cell 
  — 
  or 
  of 
  the 
  cell 
  aggregates 
  — 
  is, 
  in 
  the 
  last 
  resort, 
  almost 
  

   certainly 
  of 
  this 
  nature 
  ; 
  but 
  the 
  whole 
  problem 
  turns 
  on 
  the 
  

   question 
  as 
  to 
  whether 
  the 
  discrete 
  particles 
  (chromo- 
  

   somes) 
  are 
  endowed 
  with 
  different 
  activites, 
  or 
  whether 
  

   each 
  of 
  them 
  merely 
  acts 
  as 
  a 
  portion 
  of 
  a 
  homogeneous 
  

   whole. 
  

  

  Many 
  a 
  priori 
  considerations 
  appear 
  to 
  be 
  opposed 
  to 
  

   the 
  latter 
  view, 
  and 
  seem 
  strongly 
  to 
  point 
  to 
  a 
  difference 
  

   between 
  the 
  different 
  chromosomes, 
  each 
  of 
  which, 
  by 
  itself 
  

   or 
  in 
  combination 
  with 
  others, 
  can 
  produce 
  a 
  definite 
  effect 
  in 
  

   directing 
  or 
  influencing 
  the 
  latent 
  activities 
  present 
  in 
  the 
  

   nucleus 
  or 
  the 
  cell. 
  The 
  complex 
  series 
  of 
  events 
  during 
  a 
  

   normal 
  somatic 
  mitosis 
  whereby 
  an 
  exact 
  longitudinal 
  

   division 
  of 
  the 
  chromosome 
  material 
  is 
  effected 
  has 
  often 
  been 
  

   commented 
  on^ 
  and 
  it 
  is 
  diflScult 
  to 
  comprehend 
  why 
  longi- 
  

   tudinal 
  fission 
  should 
  be 
  so 
  invariable 
  a 
  rule 
  in 
  normal 
  differ- 
  

   entiating 
  body 
  cells, 
  unless 
  there 
  is 
  an 
  individuality 
  possessed 
  

   by 
  the 
  chromosomes 
  themselves 
  — 
  an 
  individuality 
  that 
  would 
  

   manifest 
  itself 
  in 
  retaining 
  or 
  modifying 
  the 
  specific 
  traits 
  

   distinctive 
  of 
  the 
  organism. 
  Again, 
  the 
  remarkable 
  constancy 
  

   of 
  numbers, 
  especially 
  in 
  the 
  reproductive 
  tissues, 
  fails 
  to 
  

   find 
  any 
  satisfactory 
  explanation. 
  

  

  It 
  is 
  true 
  that 
  some, 
  like 
  O. 
  Hertwig, 
  have 
  regarded 
  

   equality 
  of 
  mass 
  as 
  the 
  essential 
  advantage 
  secured 
  by 
  longi- 
  

   tudinal 
  fission, 
  but 
  this 
  standpoint, 
  from 
  the 
  point 
  of 
  view 
  of 
  

   the 
  facts 
  of 
  ontogeny, 
  seems 
  an 
  unsatisfactory 
  one. 
  The 
  

   celerity 
  with 
  which 
  two 
  cells 
  of 
  common 
  parentage 
  may 
  pro- 
  

   ceed 
  to 
  differ, 
  in 
  spite 
  of 
  the 
  equivalence 
  of 
  their 
  nuclear 
  

   mass 
  at 
  the 
  instant 
  of 
  their 
  genesis, 
  coupled 
  with 
  the 
  rapidity 
  

   with 
  which 
  nuclei 
  may 
  gi-ow 
  or 
  diminish 
  in 
  size, 
  are 
  difficult 
  

   facts 
  to 
  reckon 
  with 
  when 
  regarded 
  from 
  this, 
  comparatively 
  

   speaking, 
  simple 
  standpoint. 
  The 
  results 
  of 
  experiments 
  on 
  

   regeneration 
  of 
  embryos 
  and 
  missing 
  portions 
  of 
  older 
  

  

  