﻿THE 
  MAIOTTC 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  497 
  

  

  within 
  a 
  limited 
  and 
  approximately 
  constant 
  mass 
  of 
  sub- 
  

   stance. 
  Hence 
  if 
  we 
  admit 
  that 
  the 
  chromosomes 
  divide 
  

   longitudinally 
  (anaschistically) 
  throughout 
  the 
  maiotic, 
  as 
  in 
  

   the 
  somatic, 
  cell 
  generations^ 
  we 
  are 
  confronted 
  with 
  the 
  

   following 
  difficulties 
  : 
  

  

  1. 
  The 
  reduced 
  chromosomes 
  cannot 
  continue 
  to 
  be 
  com- 
  

   pounded 
  of 
  the 
  antecedent 
  preraaiotic 
  chromosomes 
  and 
  at 
  

   the 
  same 
  time 
  preserve 
  their 
  organisation 
  unchanged. 
  They 
  

   must 
  each 
  represent 
  a 
  new 
  structure. 
  Why, 
  then, 
  under 
  these 
  

   circumstances 
  do 
  they 
  appear 
  strictly 
  as 
  half 
  the 
  number 
  

   characteristic 
  of 
  the 
  preceding 
  nuclei 
  ? 
  For 
  if 
  the 
  equal 
  

   division 
  of 
  the 
  mass 
  be 
  the 
  essential 
  feature, 
  there 
  would 
  

   seem 
  to 
  be 
  no 
  specific 
  reason 
  for 
  constancy 
  in 
  respect 
  of 
  

   number. 
  

  

  2. 
  If 
  chromosomes 
  arise 
  de 
  novo 
  from 
  the 
  substance 
  of 
  the 
  

   previous 
  ones 
  that 
  have 
  now 
  lost 
  their 
  identity, 
  the 
  only 
  

   result 
  must 
  be 
  a 
  mingling 
  of 
  substance, 
  but 
  no 
  retention 
  

   of 
  organisation. 
  But 
  such 
  a 
  mingling 
  cannot 
  be 
  simply 
  

   of 
  the 
  nature 
  of 
  a 
  mixture. 
  It 
  is 
  more 
  akin 
  to 
  the 
  produc- 
  

   tion 
  of 
  a 
  new 
  chemical 
  combination 
  at 
  each 
  reduction, 
  since 
  

   the 
  parental 
  masses 
  of 
  nuclear 
  substance 
  can 
  scarcely 
  be 
  

   supposed 
  to 
  be 
  absolutely 
  identical, 
  especially 
  in 
  the 
  case 
  of 
  

   hybrids. 
  But 
  it 
  is 
  just 
  in 
  hybrids 
  that 
  we 
  meet 
  perhaps 
  the 
  

   strongest 
  evidence 
  in 
  favour 
  of 
  the 
  continued 
  existence 
  of 
  

   the 
  primordia 
  as 
  attached 
  to 
  discrete 
  particles 
  retaining 
  their 
  

   individuality, 
  for 
  how 
  could 
  the 
  remarkable 
  numerical 
  re- 
  

   lationships 
  of 
  dominants 
  and 
  recessives 
  be 
  otherwise 
  main- 
  

   tained 
  ? 
  

  

  The 
  difficulties 
  briefly 
  sketched 
  above 
  seem 
  to 
  render 
  

   the 
  existence 
  of 
  a 
  double 
  longitudinal 
  fission 
  during 
  the 
  

   mitoses 
  in 
  question 
  not 
  only 
  inherently 
  improbable 
  but 
  im- 
  

   possible 
  to 
  reconcile 
  with 
  the 
  facts 
  so 
  strongly 
  pointing 
  to 
  

   the 
  important 
  influence 
  exerted 
  by 
  the 
  separate 
  chromosomes 
  

   in 
  controlling 
  and 
  determinating 
  the 
  organisation 
  of 
  an 
  indi- 
  

   vidual 
  plant 
  or 
  animal. 
  

  

  Moreover, 
  such 
  a 
  mode 
  of 
  fission, 
  with 
  the 
  consequences 
  

   that 
  accrue 
  from 
  it, 
  would 
  afford 
  no 
  satisfactory 
  explanation 
  

  

  