﻿444 
  J. 
  W. 
  JENKINSON. 
  

  

  troclia, 
  Rhynclielniis, 
  and 
  Toxopneustes 
  ; 
  and 
  in 
  Ascaris^ 
  

   according 
  to 
  von 
  Erlanger, 
  but 
  not 
  Boveri 
  (1888). 
  

  

  The 
  slight 
  temporary 
  depression 
  at 
  the 
  surface 
  of 
  the 
  egg 
  

   over 
  the 
  polar 
  spindle 
  which 
  I 
  have 
  noticed 
  in 
  the 
  Axolotl 
  has 
  

   been 
  seen 
  by 
  others 
  also 
  (Francotte, 
  Griffin, 
  von 
  Kostanecki 
  

   [1896], 
  Linville). 
  

  

  2. 
  Reduction 
  of 
  the 
  chromosomes. 
  

  

  It 
  is 
  no 
  part 
  of 
  my 
  programme 
  to 
  enter 
  at 
  any 
  length 
  into 
  

   this 
  vexing 
  and 
  perhaps 
  fruitless 
  controversy. 
  

  

  As 
  far 
  as 
  the 
  Amphibian 
  ovum 
  is 
  concerned, 
  however, 
  it 
  is 
  

   clear 
  from 
  the 
  careful 
  work 
  of 
  Carnoy 
  that 
  in 
  the 
  second 
  

   maturation 
  division 
  the 
  chromosomes 
  are 
  split 
  longitudinally. 
  

   What 
  happens 
  to 
  them 
  in 
  the 
  first 
  polar 
  spindle 
  is 
  more 
  

   difficult 
  to 
  determine, 
  as 
  this 
  depends, 
  as 
  I 
  have 
  pointed 
  out 
  

   above, 
  very 
  largely 
  on 
  the 
  view 
  we 
  take 
  of 
  the 
  manner 
  of 
  their 
  

   formation 
  in 
  the 
  first 
  instance. 
  

  

  On 
  this 
  matter 
  there 
  are 
  two 
  conflicting 
  opinions. 
  Accord- 
  

   ing 
  to 
  the 
  observations 
  of 
  Born 
  on 
  Triton 
  — 
  and 
  Riickert 
  

   (1892) 
  has 
  made 
  similar 
  statements 
  for 
  the 
  Elasmobranchs 
  — 
  

   the 
  chromosomes 
  persist 
  in 
  the 
  nucleus 
  throughout 
  the 
  whole 
  

   period 
  of 
  growth 
  of 
  the 
  oocyte, 
  although 
  they 
  cease 
  to 
  be 
  

   chromatic 
  ; 
  at 
  the 
  time 
  of 
  maturation 
  the 
  chromosomes 
  of 
  the 
  

   first 
  polar 
  spindle 
  are 
  formed 
  from 
  them, 
  quite 
  independently 
  

   of 
  the 
  numerous 
  chromatic 
  nucleoli 
  which 
  are 
  present 
  in 
  the 
  

   germinal 
  vesicle 
  and 
  cast 
  out 
  into 
  the 
  cytoplasm 
  when 
  the 
  

   nuclear 
  membrane 
  disappears. 
  This 
  view 
  has 
  been 
  adopted 
  by 
  

   Miss 
  King 
  in 
  her 
  researches 
  on 
  the 
  maturation 
  of 
  the 
  toad's 
  

  

  egg- 
  

  

  The 
  other 
  view 
  is 
  that 
  advocated 
  originally 
  by 
  Schulze 
  and 
  

   later 
  by 
  Carnoy 
  and 
  Fick 
  (1899). 
  According 
  to 
  Carnoy 
  the 
  

   chromosomes 
  of 
  the 
  young 
  oocyte 
  are 
  disintegrated. 
  The 
  

   chromatin 
  passes 
  into 
  a 
  state 
  of 
  solution 
  and 
  is 
  continually 
  

   being 
  reprecipitated 
  — 
  as 
  nucleoli 
  — 
  and 
  redisintegrated 
  and 
  

   dissolved 
  during 
  the 
  long 
  period 
  of 
  growth 
  of 
  the 
  oocyte. 
  

   During 
  this 
  period 
  the 
  yolk-granules 
  are 
  deposited 
  in 
  the 
  

  

  