﻿THE 
  AIAIOTIO 
  PHASE 
  IN 
  ANIAIALS 
  AND 
  PLANTS. 
  491 
  

  

  Pke-maiotic 
  Phase. 
  Maiotic 
  Phase. 
  Post-maiotic 
  Ph-^se. 
  

  

  Occurs 
  in 
  animals 
  and 
  Occurs 
  in 
  animals 
  and 
  Occurs 
  in 
  plants 
  (game- 
  

  

  plants, 
  and 
  begins 
  with 
  plants, 
  topliyte 
  of 
  the 
  higher 
  

  

  tlie 
  development 
  of 
  the 
  forms;. 
  Normally 
  ab- 
  

  

  fertilised 
  ovum. 
  sent 
  in 
  animals. 
  

  

  We 
  further 
  suggest 
  the 
  desirability 
  of 
  using 
  definite 
  terms 
  

   in 
  order 
  to 
  express 
  and 
  describe 
  the 
  diverse 
  aspects 
  pre- 
  

   sented 
  by 
  different 
  classes 
  of 
  mitoses 
  in 
  a 
  given 
  animal 
  or 
  

   plant 
  ; 
  and 
  since 
  in 
  any 
  cellular 
  life 
  cycle 
  all 
  the 
  pre-maiotic 
  

   and 
  post-maiotic, 
  as 
  well 
  as 
  one 
  of 
  the 
  two 
  maiotic, 
  divi- 
  

   sions 
  are 
  essentially 
  characterised 
  by 
  the 
  longitudinal 
  

   splitting 
  of 
  the 
  mature 
  chromosomes, 
  these 
  might, 
  for 
  

   descriptive 
  purposes, 
  be 
  termed 
  Anaschistic 
  mitoses. 
  

   Similarly, 
  inasmuch 
  as 
  the 
  characteristic 
  feature 
  of 
  the 
  other 
  

   of 
  the 
  two 
  maiotic 
  divisions 
  (usually, 
  if 
  not 
  always, 
  the 
  first) 
  

   is 
  transverse 
  as 
  regards 
  the 
  mature 
  bivalent 
  chromosomes 
  

   this 
  division 
  might 
  be 
  designated 
  as 
  Diaschistic. 
  

  

  As 
  regards 
  the 
  words 
  "heterotype 
  " 
  and 
  "homotype," 
  they 
  

   are 
  not 
  really 
  necessary 
  if 
  our 
  term 
  of 
  maiosis 
  be 
  accepted. 
  

   They 
  could 
  more 
  simply 
  be 
  designated 
  as 
  the 
  first 
  and 
  second 
  

   maiotic 
  divisions 
  respectively. 
  But 
  inasmuch 
  as 
  they 
  are 
  so 
  

   well 
  understood, 
  and 
  so 
  widely 
  adopted, 
  we 
  have 
  continued 
  

   to 
  use 
  them 
  in 
  the 
  sense 
  as 
  already 
  defined. 
  

  

  The 
  series 
  of 
  phenomena 
  that 
  for 
  convenience 
  may 
  be 
  in- 
  

   cluded 
  under 
  the 
  terms 
  of 
  '^ 
  regeneration," 
  'Variation," 
  and 
  

   "heredity" 
  have 
  gradually 
  come 
  to 
  be 
  more 
  clearly 
  apprehended 
  

   as 
  resolving 
  themselves 
  into 
  cell-problems. 
  And 
  in 
  reflecting 
  

   on 
  the 
  results 
  of 
  modern 
  cytological 
  investigations 
  in 
  this 
  

   connection, 
  it 
  is 
  impossible 
  to 
  escape 
  the 
  idea 
  that 
  in 
  some 
  

   way 
  or 
  other 
  the 
  nuclear 
  chromosomes 
  of 
  an 
  organism 
  must 
  

   be 
  intimately 
  related 
  with 
  the 
  structural 
  characters 
  by 
  which 
  

   it 
  is 
  distinguished. 
  The 
  intricate 
  sequence 
  of 
  changes 
  under- 
  

   gone 
  by 
  the 
  chromosomes 
  during 
  the 
  phases 
  of 
  a 
  nuclear 
  divi- 
  

   sion, 
  coupled 
  with 
  the 
  surprising 
  degree 
  of 
  similarity 
  betrayed 
  

   in 
  these 
  respects 
  between 
  the 
  cells 
  of 
  plants 
  on 
  the 
  one 
  hand 
  

   and 
  of 
  animals 
  on 
  the 
  other, 
  renders 
  it 
  impossible 
  to 
  avoid 
  the 
  

   conclusion 
  that 
  a 
  fundamental 
  significance 
  lies 
  behind 
  the 
  

  

  