﻿THE 
  MAIOTIC 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  553 
  

  

  somes, 
  it 
  is 
  clear 
  that 
  on 
  the 
  basis 
  of 
  the 
  mode 
  of 
  reduction 
  

   maintained 
  in 
  this 
  paper 
  the 
  Mendelian 
  proportion 
  of 
  

   D 
  + 
  2DR 
  + 
  E, 
  ought 
  to 
  follow, 
  where 
  D 
  represents 
  a 
  

   character 
  (dominant) 
  and 
  R 
  the 
  correlative 
  character 
  (reces- 
  

   sive) 
  derived 
  from 
  each 
  parent 
  respectively. 
  It 
  is 
  further 
  

   obvious 
  that 
  such 
  a 
  result 
  can 
  only 
  follow 
  provided 
  the 
  

   chromosomes 
  of 
  the 
  one 
  parent 
  combine 
  with 
  those 
  of 
  

   the 
  other 
  in 
  such 
  a 
  way 
  that 
  each 
  bivalent 
  chromosome 
  

   of 
  the 
  heterotype 
  prophase 
  consists 
  of 
  somatic 
  chromo- 
  

   somes 
  derived 
  from 
  each 
  of 
  the 
  two 
  parents 
  respectively. 
  

   For 
  if 
  such 
  bivalent 
  chromosomes 
  are 
  formed 
  of 
  pairs 
  

   derived 
  from 
  the 
  same 
  parent, 
  then 
  a 
  simple 
  analysis 
  will 
  

   show 
  that 
  quite 
  different 
  relations 
  will 
  obtain, 
  and 
  that 
  in 
  

   the 
  case 
  of 
  the 
  further 
  hybrid 
  offspring 
  the 
  D 
  and 
  R 
  qualities 
  

   will 
  not 
  be 
  present 
  in 
  equivalent 
  proportions. 
  The 
  latter 
  

   case 
  would, 
  however, 
  not 
  affect 
  the 
  validity 
  of 
  the 
  views 
  here 
  

   advanced 
  of 
  the 
  nature 
  of 
  reduction, 
  but 
  only 
  the 
  parental 
  

   origin 
  of 
  the 
  constituents 
  of 
  each 
  bivalent 
  chromosome.^ 
  

  

  Of 
  course 
  the 
  simple 
  Mendelian 
  relation 
  will 
  only 
  occur 
  in 
  

   cases 
  in 
  which 
  the 
  chromosomes 
  are 
  distributed 
  in 
  the 
  

   average 
  manner. 
  If 
  some 
  combinations 
  are 
  more 
  favoured 
  

   than 
  others, 
  then 
  the 
  proportions 
  will 
  be 
  correspondingly 
  

   disturbed. 
  Similarly 
  with 
  the 
  mosaic 
  hybrids; 
  these 
  might 
  

   be 
  due, 
  as 
  has 
  "been 
  pointed 
  out 
  by 
  others, 
  to 
  a 
  preponderant 
  

   influence 
  of 
  certain 
  chromosomes, 
  or 
  of 
  combinations 
  of 
  each, 
  

   in 
  certain 
  parts 
  of 
  the 
  organism. 
  But 
  we 
  would 
  suggest 
  that 
  

   it 
  might 
  also 
  be 
  explained 
  in 
  another 
  way. 
  The 
  chromosomes, 
  

   as 
  we 
  have 
  been 
  careful 
  to 
  point 
  out, 
  cannot 
  be 
  regarded 
  as 
  

   the 
  primordia 
  of 
  characters, 
  but 
  only 
  as 
  the 
  agents 
  that 
  are 
  

   competent 
  to 
  produce 
  serial 
  changes 
  in 
  the 
  protoplasm 
  they 
  

   can 
  influence. 
  This 
  implies 
  that 
  the 
  substance 
  on 
  which 
  they 
  

   work, 
  or 
  which 
  tliey 
  can 
  " 
  activate,^' 
  must 
  also 
  be 
  reckoned 
  

   with. 
  The 
  recent 
  work 
  on 
  regeneration 
  clearly 
  emphasises 
  the 
  

   importance 
  of 
  the 
  cytoplasm, 
  which 
  in 
  this 
  connection 
  may 
  

   be 
  compared 
  with 
  raw 
  material, 
  and 
  it 
  is 
  certainly 
  a 
  factor 
  by 
  no 
  

   means 
  destitute 
  of 
  significance. 
  If 
  the 
  raw 
  material 
  differs, 
  

   * 
  See 
  footnote 
  on 
  p. 
  551. 
  

  

  VOL. 
  48, 
  PART 
  4. 
  NEW 
  SERIES. 
  40 
  

  

  