﻿MATURATrON, 
  ETC., 
  OF 
  THE 
  EGG 
  OK 
  THK 
  AXOLOTL. 
  413 
  

  

  immediately 
  below 
  the 
  surface, 
  there 
  are 
  a 
  few 
  fibres 
  radiat- 
  

   ing' 
  between 
  the 
  yoke-gi-anules. 
  These 
  " 
  mantle 
  " 
  fibres 
  are 
  

   the 
  only 
  representatives 
  of 
  an 
  aster. 
  

  

  At 
  the 
  outer 
  pole 
  the 
  fibi-es 
  appear 
  all 
  to 
  converge 
  in 
  a 
  

   single 
  dense 
  mass, 
  but 
  at 
  the 
  inner 
  end 
  their 
  behaviour 
  varies 
  

   in 
  different 
  preparations. 
  In 
  some 
  cases 
  this 
  end 
  of 
  the 
  

   spindle 
  is 
  also 
  unipolar, 
  but 
  in 
  other 
  cases, 
  as 
  in 
  that 
  figured, 
  

   the 
  fibres 
  undoubtedly 
  converge 
  to 
  two 
  separate 
  points. 
  

  

  There 
  is 
  no 
  trace 
  of 
  any 
  centrosome 
  at 
  either 
  spindle 
  pole 
  

   except 
  the 
  mass 
  formed 
  by 
  the 
  convergence 
  of 
  the 
  fibres. 
  

  

  The 
  chromosomes 
  at 
  this 
  stage 
  have 
  the 
  form 
  of 
  rings, 
  

   which 
  by 
  being 
  indented 
  at 
  four 
  places 
  assume 
  the 
  shape 
  of 
  

   a 
  cross. 
  The 
  cross 
  is 
  so 
  placed 
  on 
  the 
  spindle 
  that 
  two 
  arms 
  

   — 
  those 
  by 
  which 
  it 
  is 
  attached 
  to 
  the 
  fibres 
  — 
  are 
  parallel 
  to 
  

   the 
  spindle-axis, 
  while 
  the 
  remaining 
  two 
  are 
  either 
  in 
  or 
  

   parallel 
  to 
  the 
  equatorial 
  plane, 
  and 
  therefore 
  at 
  right 
  angles 
  

   to 
  the 
  first 
  two. 
  These 
  equatorial 
  arms, 
  however, 
  do 
  not 
  lie 
  

   in 
  the 
  same 
  plane 
  as 
  the 
  two 
  meridional 
  arms, 
  but 
  project 
  

   outwards, 
  making 
  an 
  angle 
  with 
  one 
  another. 
  Each 
  such 
  

   cruciform 
  ring 
  is 
  in 
  reality 
  composed 
  of 
  two 
  chromosomes, 
  

   the 
  extremities 
  of 
  which 
  can 
  be 
  distinctly 
  seen 
  at 
  the 
  ends 
  of 
  

   the 
  equatorial 
  arms 
  of 
  the 
  cross. 
  These 
  extremities 
  are 
  

   often 
  twisted 
  over 
  one 
  another, 
  as 
  indicated 
  in 
  the 
  figure. 
  

  

  Though 
  the 
  above 
  description 
  may 
  be 
  taken 
  as 
  appropriate 
  

   to 
  a 
  typical 
  chromosome 
  of 
  this 
  stage, 
  many 
  of 
  these 
  bodies 
  

   are 
  exceedingly 
  irregular 
  in 
  form, 
  twisted 
  and 
  contorted 
  into 
  

   many 
  curious 
  shapes. 
  Such 
  irregularities 
  in 
  the 
  shape 
  of 
  the 
  

   chromosomes 
  in 
  the 
  first 
  maturation 
  spindle 
  have 
  been 
  de- 
  

   scribed 
  by 
  many 
  authors, 
  notably 
  by 
  Griffin 
  for 
  Thalassema, 
  

   as 
  well 
  as 
  by 
  Carnoy 
  and 
  Le 
  Brun 
  for 
  the 
  Amphibia. 
  

  

  The 
  chromosomes 
  do 
  not 
  all 
  lie 
  in 
  the 
  equatorial 
  plane, 
  and 
  

   are 
  not 
  confined 
  to 
  the 
  outer 
  surface 
  of 
  the 
  spindle. 
  They 
  are 
  

   scattered 
  irregularly 
  through 
  it 
  and 
  at 
  different 
  levels. 
  In 
  

   the 
  spindle, 
  therefore, 
  the 
  fibres 
  — 
  or 
  rather 
  the 
  fibre-bundles 
  

   — 
  attached 
  to 
  the 
  chromosomes 
  are 
  mingled 
  with 
  those 
  which 
  

   pass 
  from 
  pole 
  to 
  pole, 
  and 
  the 
  spindle 
  is 
  " 
  mixed" 
  according 
  

   to 
  Meves' 
  (1896, 
  1898) 
  nomenclature. 
  

  

  