﻿MATURATION, 
  EIC, 
  OF 
  THE 
  EGG 
  OF 
  THE 
  AXOLOTL. 
  479 
  

  

  Fig. 
  8. 
  — 
  Tlie 
  second 
  polar 
  body 
  completely 
  formed, 
  but 
  not 
  yet 
  quite 
  

   constricted 
  off. 
  Note 
  the 
  protrusion 
  of 
  tlie 
  vitelline 
  membrane. 
  The 
  cliromo- 
  

   somes 
  in 
  both 
  polar 
  body 
  and 
  egg 
  converge 
  by 
  their 
  apices; 
  in 
  the 
  latter 
  

   they 
  lie 
  in 
  a 
  clear 
  area. 
  

  

  EiG. 
  9. 
  — 
  First 
  polar 
  body, 
  cut 
  equatorially. 
  Notice 
  vacuolated 
  cyto- 
  

   plasm, 
  agglomerated 
  yolk-granuleS; 
  pigment 
  and 
  cruciform 
  jagged 
  chromo- 
  

   somes. 
  

  

  Fig. 
  10. 
  — 
  First 
  polar 
  body 
  with 
  nucleus 
  partially 
  reconstituted. 
  The 
  

   chromosomes, 
  though 
  still 
  distinct, 
  lie 
  in 
  an 
  oval 
  area. 
  This, 
  however, 
  may 
  

   possibly 
  be 
  one 
  of 
  the 
  products 
  of 
  division 
  of 
  the 
  first 
  polar 
  body 
  (see 
  text). 
  

  

  Figs. 
  11 
  — 
  14. 
  — 
  Second 
  polar 
  body 
  showing 
  the 
  reconstruction 
  of 
  the 
  

   nucleus. 
  Figs. 
  11, 
  12 
  and 
  14 
  are 
  cut 
  equatorially. 
  Notice 
  vacuolated 
  cyto- 
  

   plasm, 
  pigment 
  and 
  clumps 
  of 
  yolk-granules. 
  In 
  Fig. 
  11 
  there 
  are 
  vacuoles 
  

   round 
  the 
  chromosomes. 
  In 
  Fig. 
  12 
  these 
  vacuoles 
  have 
  united 
  into 
  one 
  

   oval 
  nuclear 
  vacuole, 
  the 
  wall 
  of 
  which 
  forms 
  the 
  nuclear 
  membrane 
  ; 
  the 
  

   chromosomes 
  are 
  still 
  distinct. 
  In 
  Fig. 
  13 
  the 
  chromosomes 
  are 
  still 
  dist.ir.ct, 
  

   but 
  are 
  sending 
  out 
  processes 
  to 
  one 
  another 
  and 
  to 
  the 
  wall, 
  while 
  in 
  Fig. 
  

   14 
  they 
  have 
  given 
  rise 
  to 
  a 
  very 
  coarse 
  reticulum. 
  

  

  Figs. 
  15—41. 
  Fertilisation. 
  

  

  Fig. 
  15. 
  — 
  The 
  spermatozoon 
  with 
  head, 
  middle-piece 
  and 
  tail 
  lying 
  in 
  a 
  

   clear 
  area, 
  slightly 
  pigmented, 
  but 
  devoid 
  of 
  yolk-granules, 
  the 
  sperm-sphere. 
  

   The 
  tail 
  (on 
  the 
  left) 
  is 
  pointing 
  towards 
  the 
  sperm-path. 
  

  

  Fig. 
  16. 
  — 
  A 
  little 
  later. 
  The 
  sperm-head 
  has 
  shortened 
  and 
  thickened; 
  

   the 
  tail 
  is 
  seen 
  to 
  the 
  right. 
  The 
  middle-piece 
  has 
  vanished. 
  Instead, 
  the 
  

   centre 
  of 
  the 
  clear 
  area 
  is 
  now 
  occupied 
  by 
  a 
  vacuolated 
  pigment 
  -free 
  mass. 
  

   From 
  this 
  start 
  the 
  radiations 
  of 
  the 
  sperm-aster 
  which 
  have 
  meanwhile 
  

   been 
  developed. 
  

  

  Fig. 
  17. 
  — 
  A 
  little 
  earlier 
  than 
  the 
  last. 
  The 
  central 
  mass 
  is 
  finely 
  radiate, 
  

   and 
  in 
  it 
  is 
  a 
  small 
  irregular 
  vacuolated 
  body 
  which 
  may 
  be 
  middle-piece 
  or 
  

   perhaps 
  tail. 
  The 
  rest 
  of 
  the 
  sperm-head 
  is 
  in 
  the 
  next 
  section. 
  

  

  Fig. 
  18. 
  — 
  A 
  little 
  later 
  than 
  Fig. 
  16. 
  The 
  sperm-head 
  has 
  become 
  shorter 
  

   and 
  thicker 
  still 
  ; 
  it 
  is 
  obtusely 
  conical. 
  Its 
  vacuolatiou 
  has 
  increased. 
  

  

  Fig. 
  19. 
  — 
  An 
  accessory 
  sperm-nucleus 
  with 
  centrosome. 
  Tiie 
  nucleus 
  

   contains 
  large 
  plasmosomes 
  staining 
  black 
  with 
  iron-haematoxylin, 
  and 
  

   minutely 
  divided 
  granules 
  of 
  chromatin 
  ; 
  these 
  stain 
  faintly. 
  There 
  is 
  an 
  

   achromatic 
  reticulum. 
  The 
  centrosome 
  lies 
  in 
  front 
  of 
  (right-hand 
  side 
  in 
  

   the 
  figure) 
  the 
  nucleus; 
  between 
  it 
  and 
  the 
  nucleus 
  are 
  fine 
  parallel 
  "spindle" 
  

   fibres. 
  It 
  is 
  granular. 
  Large 
  vacuoles 
  are 
  developing 
  in 
  the 
  centre 
  of 
  the 
  

   sperm-aster. 
  

  

  Fig. 
  20.— 
  Sperm-nucleus 
  in 
  an 
  earlier 
  stage, 
  coarsely 
  reticular 
  (the 
  section 
  

   does 
  not 
  pass 
  through 
  the 
  middle 
  of 
  the 
  nucleus, 
  the 
  full 
  length 
  of 
  which 
  has 
  

  

  