﻿THE 
  MATOTIO 
  PHASE 
  TN 
  ANIMALS 
  AND 
  PLANTS. 
  505 
  

  

  that 
  characterise 
  the 
  reduction 
  divisions 
  in 
  the 
  representatives 
  

   of 
  both 
  kingdoms 
  alike. 
  We 
  are 
  convinced 
  that 
  it 
  is 
  highly 
  

   improbable 
  that 
  these 
  obvious 
  similarities 
  mask 
  a,ny 
  funda- 
  

   mentally 
  important 
  differences. 
  

  

  The 
  extreme 
  ordei'liness 
  to 
  be 
  observed 
  in 
  the 
  whole 
  pro- 
  

   cess 
  strongly 
  suggests 
  that 
  in 
  both 
  kingdoms 
  the 
  true 
  

   sequence 
  and 
  the 
  actual 
  natui'e 
  of 
  the 
  processes 
  involved 
  

   will 
  turn 
  out 
  to 
  be 
  identical. 
  Otherwise 
  the 
  vei'y 
  orderliness 
  

   of 
  the 
  process 
  finds 
  no 
  meaning. 
  And 
  if 
  it 
  be 
  true^ 
  as 
  we 
  

   believe 
  it 
  to 
  be, 
  that 
  we 
  can 
  gauge 
  the 
  importance 
  of 
  phe- 
  

   nomena 
  in 
  the 
  organic 
  world 
  by 
  the 
  regularity 
  of 
  their 
  

   appearance 
  and 
  procedure, 
  then 
  it 
  would 
  be 
  difficult 
  to 
  dis- 
  

   cover 
  any 
  instance 
  that 
  more 
  amply 
  fulfils 
  the 
  required 
  con- 
  

   dition 
  than 
  do 
  these 
  complex 
  series 
  of 
  changes 
  involved 
  in 
  an 
  

   ordinary 
  nuclear 
  division, 
  as 
  well 
  as 
  the 
  no 
  less 
  remarkable 
  

   and 
  constant 
  deviations 
  from 
  it 
  that 
  characterise 
  the 
  hetero- 
  

   type 
  mitosis. 
  

  

  The 
  results 
  of 
  our 
  investigations, 
  set 
  forth 
  in 
  the 
  following 
  

   pages, 
  have 
  been 
  such 
  as 
  to 
  convince 
  us 
  that 
  so 
  far 
  as 
  

   metazoa 
  and 
  metaphyte 
  are 
  concerned, 
  a 
  real 
  similarity 
  

   between 
  the 
  process 
  of 
  reduction, 
  as 
  it 
  occurs 
  in 
  animals 
  and 
  

   plants, 
  does 
  obtain. 
  

  

  The 
  reduction 
  is 
  achieved 
  by 
  the 
  association 
  or 
  by 
  the 
  

   non-separation 
  of 
  somatic 
  pairs 
  of 
  chromosomes 
  during 
  the 
  

   heterotype 
  prophase. 
  

  

  The 
  heterotype 
  mitosis 
  essentially 
  consists 
  in 
  the 
  separa- 
  

   tion 
  and 
  distribution 
  between 
  the 
  daughter 
  nuclei 
  of 
  entire 
  

   somatic 
  chromosomes, 
  the 
  separate 
  identity 
  of 
  which 
  is 
  

   masked 
  by 
  their 
  temporary 
  union 
  previously 
  to 
  the 
  onset 
  

   of 
  the 
  diaster, 
  and 
  thus 
  the 
  exact 
  numerical 
  reduction 
  is 
  

   accounted 
  for. 
  

  

  The 
  homotype 
  mitosis 
  is 
  associated 
  with 
  the 
  completion 
  of 
  

   the 
  longitudinal 
  division 
  of 
  the 
  chromosomes 
  already 
  incepted 
  

   during 
  the 
  prophase 
  of 
  the 
  heterotype 
  division. 
  

  

  If 
  (as 
  in 
  many 
  plants) 
  there 
  be 
  post-heterotype 
  cell 
  genera- 
  

   tions, 
  the 
  reduced 
  number 
  of 
  chromosomes 
  is 
  retained 
  until 
  

   the 
  occurrence 
  of 
  nuclear 
  union 
  at 
  fertilisation. 
  

  

  VOL. 
  48, 
  PART 
  4. 
  NEW 
  SERIES. 
  37 
  

  

  