﻿408 
  J. 
  W. 
  JBNKINSON. 
  

  

  I. 
  Introductory. 
  

  

  Eleven 
  years 
  have 
  elapsed 
  since 
  the 
  appearance 
  of 
  Rudolf 
  

   Fick's 
  memoir 
  on 
  the 
  fertilization 
  of 
  the 
  axolotl 
  ; 
  yet, 
  in 
  

   spite 
  of 
  the 
  host 
  of 
  authors 
  who 
  have 
  since 
  dealt 
  witli 
  this, 
  

   the 
  earliest 
  moment 
  of 
  development, 
  his 
  paper 
  still 
  stands 
  

   out 
  as 
  one 
  of 
  the 
  coinpletest 
  studies 
  of 
  the 
  behaviour 
  of 
  the 
  

   spermatozoon 
  in 
  the 
  egg. 
  

  

  My 
  own 
  investigations 
  were 
  begun 
  with 
  no 
  intention 
  of 
  

   controverting 
  Pick's 
  conclusions, 
  but 
  originated 
  merely 
  in 
  

   the 
  wish 
  to 
  demonstrate 
  the 
  process 
  of 
  fertilization 
  to 
  a 
  class 
  

   of 
  students. 
  In 
  the 
  result, 
  however, 
  I 
  have 
  found 
  myself 
  

   obliged 
  to 
  differ 
  from 
  my 
  predecessor 
  in 
  one 
  important 
  par- 
  

   ticular, 
  the 
  origin 
  of 
  the 
  cleavage 
  centrosomes 
  ; 
  and 
  if 
  in 
  

   other 
  respects 
  I 
  have 
  succeeded 
  in 
  giving 
  a 
  more 
  detailed 
  

   description 
  of 
  the 
  facts 
  it 
  must 
  be 
  set 
  down 
  simply 
  to 
  the 
  

   modern 
  improvements 
  in 
  our 
  methods 
  of 
  research. 
  

  

  I 
  have 
  also 
  included 
  the 
  phenomena 
  of 
  maturation 
  in 
  the 
  

   field 
  of 
  my 
  observations 
  ; 
  but 
  here 
  I 
  have 
  been 
  able 
  to 
  add 
  

   but 
  little 
  to 
  what 
  the 
  really 
  admirable 
  work 
  of 
  Carnoy 
  and 
  

   Le 
  Brun 
  has 
  taught 
  us 
  of 
  the 
  polar 
  divisions 
  in 
  many 
  other 
  

   Amphibia. 
  I 
  have 
  indeed 
  laboured 
  under 
  some 
  difficulty 
  here 
  

   for 
  want 
  of 
  sufficient 
  material. 
  Of 
  all 
  the 
  females 
  which 
  I 
  

   killed 
  only 
  one 
  was 
  found 
  to 
  have 
  eggs 
  in 
  her 
  oviducts. 
  

   Of 
  these 
  only 
  six, 
  in 
  the 
  upper 
  portion 
  of 
  the 
  oviduct, 
  ex- 
  

   hibited 
  stages 
  of 
  the 
  first 
  polar 
  spindle; 
  the 
  remainder, 
  a 
  

   few 
  in 
  the 
  middle 
  region 
  of 
  the 
  oviduct 
  and 
  a 
  very 
  large 
  

   number 
  in 
  the 
  uterus, 
  were 
  about 
  to 
  undergo 
  the 
  second 
  

   maturation 
  division. 
  The 
  rest 
  of 
  my 
  material, 
  which 
  is 
  

   fairly 
  abundant, 
  comprises 
  eggs 
  killed 
  at 
  various 
  intervals 
  

   after 
  laying. 
  

  

  It 
  is 
  only 
  quite 
  recently, 
  however, 
  that 
  I 
  have 
  been 
  able 
  

   to 
  secure 
  the 
  most 
  critical 
  stages; 
  I 
  owe 
  this 
  to 
  Professor 
  

   Weldon's 
  kindness 
  in 
  purchasing 
  some 
  fresh 
  axolotls 
  for 
  my 
  

   use. 
  This 
  will 
  perhaps 
  explain 
  why 
  my 
  work, 
  begun 
  as 
  long 
  

   as 
  three 
  years 
  ago, 
  is 
  only 
  published 
  now. 
  

  

  