﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  361 
  

  

  of 
  the 
  duct. 
  Near 
  its 
  point 
  of 
  opening 
  into 
  the 
  cloaca 
  however 
  the 
  

   enlargement 
  is 
  very 
  marked, 
  the 
  duct 
  forming 
  a 
  small 
  vesicle 
  in 
  

   this 
  region. 
  The 
  enlargement 
  is 
  chiefly 
  the 
  result 
  of 
  separation 
  of 
  

   the 
  walls 
  of 
  the 
  duct, 
  but 
  is 
  due 
  partly 
  to 
  the 
  thinning 
  of 
  the 
  

   epithelium 
  of 
  the 
  latter. 
  That 
  the 
  lumen 
  arises 
  as 
  a 
  split 
  and 
  not 
  

   by 
  absorption 
  of 
  any 
  part 
  of 
  the 
  inner 
  layer 
  is 
  indicated 
  by 
  the 
  

   fact 
  that 
  the 
  thinning 
  of 
  the 
  latter 
  does 
  not 
  occur 
  until 
  'after 
  the 
  

   lumen 
  has 
  appeared. 
  This 
  thinning 
  is 
  caused 
  by 
  condensation 
  of 
  

   the 
  epithelium. 
  While 
  it 
  is 
  at 
  first 
  very 
  loose 
  and 
  vacuolated 
  it 
  

   soon 
  becomes 
  dense 
  and 
  homogeneous 
  except 
  for 
  a 
  thin 
  surface 
  layer 
  

   which 
  still 
  retains 
  its 
  original 
  character. 
  To 
  this 
  latter 
  layer 
  I 
  

   shall 
  refer 
  shortly. 
  The 
  epithelium 
  now 
  consists 
  of 
  two 
  parts, 
  a 
  

   narrow 
  dense 
  basal 
  layer 
  lacking 
  fibrillae 
  or 
  other 
  evident 
  structure 
  

   except 
  the 
  nuclei, 
  which 
  having 
  a 
  greater 
  diameter 
  than 
  the 
  layer 
  

   itself 
  cause 
  frequent 
  bulgings 
  of 
  the 
  latter 
  into 
  the 
  lumen 
  of 
  the 
  

   duct 
  (Fig. 
  14), 
  and 
  the 
  thin 
  loose 
  surface 
  layer 
  just 
  mentioned. 
  This 
  

   latter 
  layer 
  is 
  not 
  always 
  easy 
  to 
  demonstrate 
  and 
  may 
  occasionally 
  

   be 
  absent. 
  From 
  the 
  first 
  layer 
  is 
  derived, 
  by 
  a 
  further 
  process 
  of 
  

   condensation 
  and 
  by 
  absorption 
  of 
  its 
  contained 
  nuclei, 
  the 
  cuticula 
  

   of 
  the 
  vagina, 
  which 
  is 
  thus 
  a 
  modified 
  epithelium. 
  The 
  nuclei 
  

   retain 
  their 
  normal 
  structure 
  for 
  some 
  time 
  after 
  the 
  condensation 
  

   of 
  the 
  basal 
  layer 
  begins, 
  and 
  are 
  only 
  later 
  absorbed. 
  The 
  process 
  

   of 
  absorption 
  I 
  have 
  not 
  traced 
  in 
  detail, 
  but 
  that 
  they 
  are 
  absorbed 
  

   and 
  not 
  extruded 
  is 
  evidenced 
  by 
  the 
  presence 
  for 
  a 
  considerable 
  

   time 
  of 
  nuclear 
  remnants 
  in 
  the 
  cuticula. 
  In 
  the 
  thin 
  surface 
  layer 
  

   of 
  the 
  epithelium 
  delicate 
  striations 
  appear, 
  which 
  thicken 
  and 
  

   separate 
  from 
  one 
  another 
  to 
  form 
  the 
  cilia 
  ^) 
  lining 
  the 
  vagina. 
  

   The 
  development 
  of 
  the 
  cilia 
  is 
  not 
  easy 
  to 
  follow, 
  but 
  it 
  is 
  possible 
  

   in 
  some 
  cases 
  to 
  trace 
  this 
  surface 
  layer 
  into 
  the 
  layer 
  of 
  cilia 
  

   thus 
  rendering 
  highly 
  probable 
  the 
  account 
  just 
  given. 
  ^j 
  During 
  

   development 
  the 
  cuticula 
  thickens 
  to 
  some 
  extent 
  and 
  the 
  ciliary 
  

   layer 
  markedly 
  so, 
  together 
  attaining 
  a 
  thickness 
  at 
  some 
  points 
  

   of 
  8 
  as 
  compared 
  with 
  3 
  Vs 
  /* 
  before 
  the 
  appearance 
  of 
  the 
  lumen 
  

   in 
  the 
  vaginal 
  anläge.^) 
  

  

  1) 
  Whether 
  these 
  are 
  functionally 
  cilia 
  or 
  not 
  cannot 
  of 
  course 
  be 
  

   said. 
  See 
  Beaun 
  (1894—1900, 
  p. 
  1415). 
  

  

  2) 
  A 
  complete 
  account 
  of 
  the 
  development 
  of 
  the 
  cilia 
  in 
  the 
  repro- 
  

   ductive 
  ducts 
  of 
  cestodes 
  I 
  have 
  not 
  found 
  in 
  any 
  author, 
  

  

  3) 
  The 
  thickness 
  of 
  course 
  varies 
  from 
  point 
  to 
  point, 
  dependant 
  

   on 
  amount 
  of 
  distension 
  of 
  the 
  duct. 
  This 
  figure 
  is 
  a 
  maximum. 
  

  

  