﻿538 
  J. 
  BRETLAND 
  PARMKR 
  AND 
  J. 
  E. 
  S. 
  MOORE. 
  

  

  tioa 
  has 
  made 
  it 
  obvious 
  that 
  although 
  the 
  main 
  features 
  of 
  

   the 
  spermatogeuesis 
  of 
  these 
  fishes 
  were 
  correctly 
  ascertained, 
  

   certain 
  aspects 
  of 
  the 
  maiotic 
  phase 
  were 
  not 
  fully 
  appreciated 
  

   at 
  the 
  time. 
  

  

  In 
  many 
  ways 
  the 
  functional 
  male 
  gland 
  of 
  an 
  elasmo- 
  

   branch 
  is 
  an 
  admirable 
  object 
  for 
  the 
  study 
  of 
  all 
  the 
  stages 
  

   of 
  development 
  in 
  the 
  sexual 
  cells; 
  but 
  it 
  is 
  also 
  true 
  that 
  

   as 
  far 
  as 
  the 
  heterotype 
  prophases 
  are 
  concerned, 
  the 
  pheno- 
  

   mena 
  in 
  these 
  fishes 
  are 
  somewhat 
  confusing, 
  and 
  are 
  far 
  

   more 
  readily 
  interpreted 
  correctly, 
  after 
  a 
  knowledge 
  of 
  what 
  

   actually 
  takes 
  place 
  has 
  been 
  obtained 
  in 
  some 
  form 
  like 
  that 
  

   of 
  the 
  cockroach. 
  

  

  In 
  the 
  various 
  forms 
  of 
  elasmobranch 
  testis 
  the 
  young 
  

   tubules 
  are 
  found 
  crowded 
  with 
  cells 
  which 
  are 
  just 
  rapidly 
  

   multiplying 
  through 
  successive 
  pre-maiotic 
  mitoses 
  as 
  they 
  

   do 
  in 
  the 
  testis 
  of 
  the 
  cockroach, 
  the 
  chief 
  distinction 
  

   between 
  the 
  fish 
  and 
  the 
  insect 
  being 
  that 
  in 
  the 
  former 
  there 
  

   is 
  present 
  a 
  much 
  more 
  complete 
  spirem 
  thread 
  than 
  in 
  the 
  

   latter; 
  in 
  fact, 
  we 
  have 
  here 
  pre-maiotic 
  prophases 
  which 
  are 
  

   directly 
  comparable 
  with 
  those 
  already 
  fully 
  described 
  by 
  

   Flemming 
  and 
  others 
  in 
  several 
  amphibian 
  types. 
  

  

  A 
  long 
  coiled 
  threadwork 
  is 
  ultimately 
  formed 
  which 
  splits 
  

   longitudinally 
  and 
  then 
  breaks 
  up 
  into 
  lengths, 
  the 
  resulting 
  

   split 
  segments 
  representing 
  the 
  twenty-four 
  somatic 
  chromo- 
  

   somes. 
  As 
  the 
  mode 
  of 
  division 
  of 
  these 
  cells 
  has 
  been 
  

   fully 
  figured 
  and 
  described 
  by 
  us, 
  it 
  will 
  be 
  unnecessary 
  to 
  

   recapitulate 
  the 
  entire 
  sequence 
  here, 
  and 
  we 
  may 
  pass 
  on 
  to 
  

   a 
  consideration 
  of 
  the 
  first 
  maiotic 
  prophase 
  itself. 
  

  

  (b) 
  The 
  Maiotic 
  Phase. 
  

  

  As 
  in 
  the 
  cockroach, 
  cells 
  which 
  are 
  about 
  to 
  pass 
  out 
  

   of 
  the 
  pre-maiotic 
  cycle 
  and 
  enter 
  upon 
  the 
  synaptic 
  meta- 
  

   morphosis 
  present 
  an 
  increase 
  in 
  their 
  chromatin, 
  and 
  a 
  

   gradual 
  enlargement, 
  which 
  for 
  a 
  time 
  seems 
  to 
  keep 
  pace 
  

   with 
  the 
  nuclear 
  metamorphosis. 
  In 
  torpedo 
  and 
  other 
  ex- 
  

   amples 
  of 
  elasmobrauch 
  fishes 
  we 
  find 
  that 
  the 
  very 
  fine 
  spirem 
  

  

  