﻿MATURATION, 
  ETC., 
  OF 
  THE 
  EGG 
  OF 
  THE 
  AXOLOTL. 
  433 
  

  

  With 
  the 
  formation 
  and 
  elongation 
  of 
  the 
  spindle-fibres 
  the 
  

   centrosomes 
  move 
  further 
  apart 
  ; 
  at 
  the 
  same 
  time 
  they 
  begin 
  

   to 
  enlarge, 
  and 
  continue 
  to 
  do 
  so 
  until 
  they 
  have 
  attained 
  a 
  

   very 
  considerable 
  size 
  (fig. 
  33) 
  . 
  P 
  a 
  r 
  i 
  p 
  a 
  s 
  s 
  u 
  with 
  this 
  enlarge- 
  

   ment 
  the 
  vacuoles 
  — 
  the 
  vacuoles 
  of 
  the 
  original 
  sperm-sphere 
  

   — 
  gradually 
  disappear. 
  I 
  believe 
  that 
  the 
  two 
  processes 
  are 
  

   intimately 
  related, 
  that, 
  in 
  fact, 
  the 
  centrosomes 
  enlarge 
  at 
  

   the 
  expense 
  of 
  these 
  vacuoles, 
  and 
  that 
  their 
  growth 
  consists 
  

   essentially 
  in 
  an 
  imbibition 
  by 
  them 
  of 
  the 
  watery 
  substance 
  

   concentrated 
  at 
  an 
  earlier 
  period 
  in 
  the 
  centre 
  of 
  the 
  sperm- 
  

   sphere. 
  

  

  This 
  growth 
  of 
  the 
  centrosomes 
  is 
  accompanied 
  by 
  the 
  

   formation 
  not 
  only 
  of 
  the 
  spindle 
  fibres, 
  but 
  also 
  of 
  the 
  polar 
  

   asters. 
  Under 
  this 
  heading 
  are 
  comprised 
  all 
  those 
  radia- 
  

   tions 
  which 
  pass 
  outwards 
  from 
  the 
  centrosomes, 
  with 
  the 
  

   exception 
  of 
  those 
  — 
  the 
  spindle 
  fibres 
  proper 
  — 
  which 
  pass 
  

   to 
  the 
  two 
  pronuclei. 
  

  

  The 
  outer 
  ends 
  of 
  these 
  astral 
  radiations 
  are 
  distinguishable 
  

   from 
  the 
  first 
  from 
  the 
  spindle-fibres 
  by 
  their 
  coarser 
  struc- 
  

   ture; 
  the 
  fibres 
  — 
  or 
  lamellas 
  — 
  are 
  stouter, 
  the 
  inter-fibrillar 
  

   spaces 
  — 
  or 
  alveoli 
  — 
  much 
  wider, 
  and 
  seem 
  to 
  be 
  identical 
  

   with 
  the 
  earlier 
  radiations 
  of 
  the 
  sperm-sphere, 
  separated, 
  as 
  

   we 
  have 
  seen, 
  by 
  the 
  elongation 
  of 
  the 
  latter 
  into 
  two 
  distinct 
  

   halves, 
  centring 
  each 
  in 
  a 
  centrosome. 
  The 
  pigment 
  which 
  

   surrounded 
  the 
  sperm 
  sphere 
  is 
  found 
  thickly 
  scattered 
  about 
  

   these 
  outer 
  rays 
  (figs. 
  31 
  — 
  34). 
  

  

  The 
  inner 
  ends 
  of 
  the 
  astral 
  rays 
  on 
  the 
  other 
  hand, 
  though 
  

   perfectly 
  continuous 
  with 
  the 
  outer, 
  diifer 
  greatly 
  from 
  them 
  

   in 
  their 
  appearance 
  and 
  in 
  the 
  mode 
  of 
  their 
  formation. 
  In 
  

   the 
  fineness 
  of 
  their 
  structure 
  they 
  resemble 
  the 
  spindle- 
  

   fibres, 
  and 
  they 
  occupy 
  the 
  space 
  previously 
  taken 
  up 
  by 
  the 
  

   large 
  terminal 
  vacuoles 
  (figs. 
  33, 
  34). 
  They 
  may, 
  and 
  indeed 
  

   must, 
  I 
  believe, 
  be 
  regarded 
  as 
  outgrowths 
  of 
  the 
  centrosomes, 
  

   developed 
  at 
  the 
  expense 
  of 
  the 
  contents 
  of 
  the 
  vacuoles 
  which 
  

   they 
  replace. 
  The 
  exact 
  nature 
  of 
  such 
  an 
  outgrowth 
  I 
  shall 
  

   have 
  occasion 
  to 
  discuss 
  later 
  on; 
  but 
  I 
  may 
  say 
  here 
  that 
  in 
  

   describing 
  the 
  process 
  by 
  this 
  term 
  1 
  do 
  not 
  mean 
  to 
  imply 
  

  

  