﻿434 
  J. 
  W. 
  JENKINSON. 
  

  

  that 
  tliey 
  consist 
  entirely 
  of 
  centrosomal 
  substance. 
  On 
  the 
  

   contrary, 
  I 
  suspect 
  that 
  we 
  have 
  here 
  to 
  do 
  with 
  the 
  precipi- 
  

   tation 
  of 
  the 
  proteids 
  of 
  the 
  cytoplasm 
  by 
  the 
  dissolved 
  

   substance 
  of 
  the 
  centrosome, 
  in 
  which 
  case 
  these 
  outgrowths 
  

   owe 
  their 
  origin 
  as 
  much 
  to 
  the 
  former 
  as 
  to 
  the 
  latter. 
  

  

  The 
  further 
  metamorphosis 
  of 
  the 
  centrosomes 
  and 
  asters 
  is 
  

   as 
  follows 
  : 
  — 
  

  

  As 
  stated 
  above, 
  the 
  inner 
  portion 
  of 
  the 
  aster 
  consists 
  of 
  

   thin, 
  closely 
  set 
  rays 
  in 
  immediate 
  contact 
  with 
  the 
  centro- 
  

   some. 
  This 
  radiate 
  structure 
  persists 
  for 
  some 
  time, 
  the 
  con- 
  

   stituent 
  rays 
  becoming 
  even 
  finer 
  and 
  more 
  closely 
  set 
  (fig. 
  

   34) 
  . 
  Later, 
  however, 
  in 
  the 
  fully 
  formed 
  spindle 
  (figs. 
  38 
  — 
  41) 
  

   the 
  radiate 
  arrangement 
  is 
  lost, 
  and 
  the 
  inner 
  portion 
  of 
  the 
  

   aster 
  becomes 
  a 
  sphere 
  with 
  an 
  exceedingly 
  fine 
  reticular 
  or 
  

   alveolar 
  structure. 
  From 
  the 
  surface 
  of 
  this 
  centrosphere 
  

   start 
  the 
  outer 
  astral 
  rays; 
  in 
  its 
  centre 
  is 
  placed 
  the 
  

   centrosome. 
  

  

  This 
  body 
  has 
  also 
  undergone 
  important 
  modifications. 
  In 
  

   the 
  earliest 
  stage 
  of 
  the 
  fertilisation 
  spindle 
  the 
  centrosomes 
  

   are 
  small, 
  round, 
  sometimes 
  axially 
  compressed 
  bodies 
  (figs. 
  

   31, 
  32) 
  ; 
  they 
  are 
  not 
  coloured 
  deeply 
  with 
  iron-hsematoxylin, 
  

   but 
  may 
  contain 
  a 
  larger 
  or 
  smaller 
  number 
  of 
  granules 
  which 
  

   do 
  stain 
  intensely 
  with 
  that 
  dye. 
  They 
  then, 
  as 
  we 
  have 
  seen, 
  

   enlarge 
  very 
  considerably 
  (fig. 
  33), 
  while 
  the 
  fibres 
  of 
  the 
  

   spindle 
  on 
  the 
  one 
  hand, 
  the 
  inner 
  astral 
  rays 
  on 
  the 
  other 
  

   grow 
  out 
  from 
  them 
  (fig. 
  34). 
  When 
  the 
  metamorphosis 
  of 
  

   the 
  inner 
  portion 
  of 
  the 
  aster 
  so 
  formed 
  is 
  completed 
  the 
  

   centrosome 
  is 
  once 
  more 
  small 
  (figs. 
  38 
  — 
  41). 
  It 
  is 
  not 
  easy 
  

   to 
  see 
  in 
  material 
  preserved 
  with 
  corrosive 
  and 
  acetic 
  (figs. 
  

   38, 
  39), 
  having 
  a 
  reticular 
  structure 
  distinguishable 
  only 
  with 
  

   difficulty 
  from 
  the 
  fine 
  reticulum 
  of 
  the 
  centrosphere 
  itself. 
  

   With 
  chromic 
  and 
  acetic 
  (figs. 
  40, 
  41), 
  however, 
  the 
  centro- 
  

   some 
  stands 
  out 
  from 
  the 
  substance 
  of 
  the 
  centrosphere 
  as 
  a 
  

   small, 
  compact, 
  homogeneous 
  body, 
  slightly 
  lobed, 
  and 
  con- 
  

   taining 
  a 
  deeply 
  staining 
  particle, 
  the 
  centriole 
  ; 
  occasionally 
  

   the 
  centriole 
  (fig. 
  40), 
  and 
  sometimes 
  the 
  Avhole 
  centrosome 
  

   (fig. 
  35, 
  a.) 
  is 
  seen 
  to 
  have 
  divided. 
  In 
  this 
  case 
  the 
  daughter 
  

  

  