﻿THE 
  MAIOTIC 
  PHASE 
  TN 
  ANIMALS 
  AND 
  PLANTS. 
  543 
  

  

  our 
  results 
  in 
  the 
  case 
  of 
  the 
  human 
  species 
  are 
  identical 
  

   with 
  those 
  obtained 
  among 
  the 
  lower 
  members 
  of 
  the 
  verte- 
  

   brate 
  class. 
  

  

  Conclusions. 
  

  

  In 
  attempting 
  to 
  form 
  any 
  opinion 
  respecting 
  the 
  conclu- 
  

   sions 
  which 
  may 
  naturally 
  emerge 
  from 
  the 
  preceding 
  mass 
  of 
  

   details 
  respectingmaiosis, 
  or 
  the 
  reduction 
  of 
  the 
  chromosomes, 
  

   in 
  animals 
  and 
  plants, 
  it 
  will 
  have 
  become 
  evident, 
  as 
  was 
  

   pointed 
  out 
  in 
  the 
  introductory 
  portion 
  of 
  this 
  memoir, 
  

   that 
  whatever 
  particular 
  significance 
  we 
  may 
  be 
  inclined 
  to 
  

   attach 
  to 
  the 
  process 
  in 
  question, 
  the 
  essential 
  details 
  are 
  in 
  

   all 
  respects 
  similar 
  throughout 
  the 
  higher 
  numbers 
  of 
  both 
  

   the 
  animal 
  and 
  the 
  vegetable 
  kingdoms. 
  

  

  Or, 
  in 
  other 
  words, 
  it 
  follows 
  that 
  whatever 
  significance 
  may 
  

   ultimately 
  be 
  attached 
  to 
  maiosis 
  itself, 
  this 
  process 
  is 
  pro- 
  

   bably 
  one 
  of 
  the 
  most 
  fundamental 
  facts 
  with 
  which 
  biologists 
  

   will 
  have 
  to 
  reckon. 
  Such 
  being 
  the 
  case, 
  it 
  may 
  not 
  be 
  un- 
  

   desirable 
  briefly 
  to 
  review 
  the 
  essential 
  features 
  of 
  reduction 
  

   before 
  attempting 
  to 
  draw 
  whatever 
  conclusions 
  may 
  seem 
  

   legitimate 
  from 
  the 
  facts 
  that 
  have 
  now 
  been 
  ascertained. 
  

  

  In 
  all 
  multicellular 
  animals 
  and 
  plants, 
  the 
  elements 
  which 
  

   from 
  the 
  first 
  division 
  of 
  the 
  ovum 
  onwards 
  gradually 
  build 
  

   up 
  the 
  soma 
  or 
  body 
  of 
  such 
  an 
  organism 
  multiply 
  in 
  general 
  

   hj 
  the 
  process 
  of 
  karyokinesis, 
  and 
  in 
  all 
  cases 
  this 
  somatic 
  

   cell 
  division 
  is 
  carried 
  out 
  on 
  an 
  essentially 
  similar 
  plan. 
  In 
  

   the 
  better 
  known 
  examples 
  of 
  such 
  division, 
  like 
  the 
  types 
  

   described 
  by 
  Flemming, 
  Rabl, 
  Strasburgei*, 
  and 
  many 
  others, 
  

   the 
  obscure 
  chromatic 
  reticulum 
  of 
  the 
  resting 
  nucleus 
  is 
  

   transformed 
  into 
  an 
  increasingly 
  definite 
  spirem 
  thi-ead, 
  

   which, 
  when 
  fully 
  formed, 
  often 
  presents 
  the 
  appearance 
  of 
  a 
  

   single 
  and 
  endlessly 
  coiled 
  filament. 
  It 
  is 
  this 
  thread 
  which 
  

   ultimately 
  breaks 
  up 
  into 
  the 
  number 
  of 
  segments 
  that 
  ai-e 
  

   destined 
  to 
  constitute 
  the 
  future 
  definitive 
  chromosomes. 
  Yet 
  

   although 
  this 
  interpretation 
  could 
  be 
  put 
  upon 
  the 
  appear- 
  

   ances 
  observed 
  during 
  the 
  prophases 
  of 
  division 
  in 
  a 
  large 
  

   number 
  of 
  animal 
  and 
  vegetable 
  forms, 
  there 
  certainly 
  exist 
  

  

  