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  The 
  histogenesis 
  of 
  the 
  reproductive 
  organs 
  of 
  

  

  Taenia 
  pisiformis. 
  

  

  By 
  

   R. 
  T. 
  Young, 
  University 
  of 
  North 
  Dakota, 
  U.S.A. 
  

  

  With 
  Plates 
  18-21. 
  

  

  This 
  work 
  is 
  a 
  continuation 
  of 
  that 
  undertaken 
  by 
  me 
  several 
  

   years 
  ago 
  on 
  the 
  histogenesis 
  of 
  Cysticercus 
  pisiformis 
  (Young, 
  1908), 
  

   and 
  on 
  which 
  a 
  preliminary 
  report 
  was 
  made 
  before 
  the 
  Eighth 
  

   International 
  Zoological 
  Congress 
  (Young, 
  1912a). 
  The 
  development 
  

   of 
  the 
  reproductive 
  organs 
  and 
  sex 
  cells 
  of 
  cestodes 
  has 
  been 
  dis- 
  

   cussed 
  hitherto 
  by 
  several 
  authors, 
  without 
  however 
  leading 
  to 
  any 
  

   definite 
  conclusions 
  regarding 
  the 
  details 
  of 
  their 
  development 
  or 
  

   the 
  existence 
  of 
  an 
  epithelium 
  in 
  their 
  ducts. 
  

  

  The 
  following 
  questions 
  are 
  still 
  unsettled: 
  

  

  Do 
  the 
  reproductive 
  anlagen 
  diiferentiate 
  from 
  one 
  or 
  several 
  

   centers 
  ? 
  

  

  What 
  is 
  the 
  homology 
  of 
  the 
  cuticle 
  present 
  in 
  part 
  of 
  the 
  duct 
  

   system 
  ? 
  

  

  Is 
  an 
  epithelium 
  present 
  thruout 
  the 
  reproductive 
  system 
  or 
  not? 
  

  

  What 
  methods 
  of 
  cell 
  ^) 
  division 
  occur 
  in 
  the 
  development 
  of 
  

   these 
  organs? 
  

  

  1) 
  For 
  my 
  conception 
  of 
  "cell" 
  (excepting 
  the 
  sex 
  and 
  yolk 
  cells) 
  as 
  

   used 
  in 
  this 
  paper 
  see 
  YoUNG, 
  1908, 
  p. 
  188. 
  

  

  