﻿THE 
  MAIOTIO 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  551 
  

  

  the 
  chromosomes 
  are 
  variable 
  or 
  constant 
  in 
  something 
  the 
  

   same 
  way 
  as 
  are 
  the 
  specific 
  characters 
  themselves. 
  

  

  Perhaps 
  we 
  may 
  be 
  permitted 
  to 
  push 
  the 
  matter 
  further. 
  

   There 
  is 
  a 
  belief 
  shared 
  by 
  some 
  investigators 
  that 
  a 
  very 
  

   close 
  relation, 
  of 
  a 
  casual 
  nature, 
  exists 
  between 
  the 
  

   chromosomes, 
  or 
  combinations 
  ot; 
  chromosomes, 
  and 
  the 
  

   specific 
  characters 
  manifested 
  by 
  an 
  organism. 
  At 
  any 
  rate, 
  

   such 
  a 
  connection 
  is 
  demonstrably 
  existent 
  between 
  the 
  

   nuclei 
  and 
  such 
  characters 
  as 
  is 
  shown, 
  for 
  example, 
  by 
  the 
  

   character 
  of 
  the 
  larvae 
  resulting 
  from 
  the 
  fertilisation 
  of 
  

   enucleated 
  fragments 
  of 
  eggs, 
  by 
  sperms 
  of 
  other 
  species, 
  or 
  

   even 
  genera, 
  of 
  Echinoderms.^ 
  

  

  And 
  the 
  remarkable 
  monstrosities, 
  and, 
  still 
  more, 
  the 
  

   occasional 
  normal 
  larv», 
  produced 
  after 
  polyspermy 
  find 
  

   their 
  most 
  natural 
  explanation 
  in 
  the 
  view 
  that 
  the 
  main 
  

   direction 
  of 
  the 
  course 
  of 
  ontogeny 
  is 
  to 
  be 
  attributed 
  to 
  the 
  

   chromosomes. 
  The 
  analysis 
  made 
  by 
  Boveri 
  ^ 
  of 
  the 
  chromo- 
  

   some 
  distribution 
  to 
  the 
  blastomeres 
  of 
  eggs 
  which 
  had 
  been 
  

   fertilised 
  by 
  two 
  sperms 
  showed 
  strong 
  reasons 
  for 
  concluding 
  

   that 
  the 
  peculiarities 
  in 
  the 
  resulting 
  offspring 
  are 
  due 
  to 
  

   disturbances 
  in 
  the 
  normal 
  relations 
  of 
  chromosomes 
  in 
  the 
  

   cells 
  to 
  which 
  they 
  are 
  distributed. 
  For 
  polyspermy 
  is 
  

   usually 
  followed 
  by 
  pluripolar 
  mitoses; 
  and 
  by 
  observing 
  

   these 
  and 
  then 
  separating 
  the 
  first-formed 
  blastomeres 
  it 
  

   was 
  possible 
  to 
  make 
  a 
  comparative 
  study 
  of 
  the 
  deviations 
  

   from 
  the 
  normal 
  form 
  under 
  different 
  conditions 
  of 
  chromo- 
  

   some 
  distribution. 
  Thus 
  it 
  is 
  clear 
  that 
  in 
  a 
  tripolar 
  mitosis 
  

   there 
  is 
  some 
  chance 
  that 
  two, 
  or 
  at 
  least 
  one^ 
  of 
  the 
  three 
  

  

  * 
  The 
  partlienogenetically 
  produced 
  echinoderm 
  larvae 
  are 
  specially 
  inter- 
  

   esting 
  iu 
  this 
  connectiou 
  since 
  they 
  only 
  contain 
  half 
  the 
  somatic 
  number 
  of 
  

   chromosomes, 
  since 
  they 
  result 
  from 
  the 
  asexual 
  development 
  of 
  a 
  post 
  maiotic 
  

   cell 
  (ovum 
  or 
  sperm). 
  This 
  fact 
  proves 
  that 
  the 
  group 
  of 
  chromosomes 
  

   present 
  in 
  such 
  a 
  post 
  maiotic 
  cell 
  are 
  sufficient 
  to 
  ensure 
  correct 
  develop- 
  

   ment, 
  and, 
  taken 
  with 
  the 
  circumstances 
  detailed 
  in 
  the 
  following 
  paragraph, 
  

   lend 
  support 
  to 
  the 
  view 
  that 
  maiosis 
  leads 
  to 
  the 
  separation 
  of 
  the 
  male 
  and 
  

   female 
  halves 
  that 
  are 
  temporarily 
  united 
  in 
  the 
  heterotype 
  prophase. 
  

  

  " 
  Boveri, 
  ' 
  Ergebnisse 
  ii. 
  d. 
  Constitution 
  d. 
  Chromatischen 
  Substanz 
  des 
  

   Zellkerns,' 
  Jena, 
  1904. 
  

  

  