﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  369 
  

  

  metamorphosed 
  into 
  a 
  cuticula 
  in 
  vas 
  deferens 
  and 
  vagina 
  as 
  de- 
  

   scribed 
  above. 
  

  

  The 
  shell 
  gland 
  also 
  arises 
  in 
  the 
  common 
  anläge 
  at 
  the 
  

   posterior 
  end 
  of 
  the 
  vagina 
  described 
  above. 
  At 
  the 
  center 
  of 
  this 
  

   anläge 
  a 
  mass 
  of 
  nuclei 
  from 
  three 
  to 
  four 
  rows 
  deep 
  arranges 
  

   itself 
  radially 
  about 
  the 
  oviduct 
  (Fig. 
  23). 
  The 
  radial 
  arrangement 
  

   of 
  these 
  nuclei 
  is 
  not 
  pronounced 
  at 
  first, 
  but 
  becomes 
  more 
  so 
  as 
  

   development 
  proceeds. 
  They 
  differ 
  in 
  no 
  way 
  save 
  position 
  and 
  

   arrangement 
  from 
  the 
  other 
  nuclei 
  in 
  the 
  mass. 
  They 
  are 
  imbedded 
  

   in 
  a 
  loose 
  network 
  of 
  cytoplasmic 
  strands, 
  whose 
  direction 
  is 
  in 
  

   general 
  radial 
  to 
  the 
  duct. 
  In 
  the 
  meshes 
  of 
  this 
  network 
  the 
  

   secretory 
  granules 
  of 
  the 
  gland 
  are 
  first 
  laid 
  down 
  indiscriminately, 
  

   later 
  becoming 
  grouped 
  into 
  more 
  definite 
  masses, 
  which 
  however 
  

   anastomose 
  with 
  one 
  another 
  and 
  do 
  not 
  form 
  dislinct 
  cells. 
  Scattered 
  

   thru 
  this 
  syncytium 
  of 
  glandular 
  masses 
  are 
  the 
  nuclei 
  of 
  the 
  gland. 
  

   Glandular 
  processes 
  pass 
  directly 
  into 
  the 
  wall 
  of 
  the 
  duct, 
  there 
  

   to 
  pour 
  their 
  secretion 
  into 
  its 
  lumen, 
  no 
  specialized 
  ducts 
  being 
  

   developed 
  (Fig. 
  18). 
  

  

  The 
  usual 
  account 
  of 
  the 
  shell 
  gland 
  describes 
  it 
  as 
  composed 
  

   of 
  distinct 
  cells, 
  while 
  Bkaun 
  (1894—1900, 
  p. 
  1437) 
  ascribes 
  to 
  it 
  

   a 
  "meist 
  grade 
  verlaufenden 
  Ausführungsgang", 
  in 
  both 
  of 
  which 
  

   respects 
  my 
  observations 
  differ. 
  

  

  The 
  existence 
  of 
  a 
  shell 
  in 
  cestode 
  ova 
  is 
  maintained 
  by 
  most 
  

   authors 
  — 
  vanBeneden 
  (1881) 
  in 
  Taenia 
  serrata, 
  Schauinsland 
  (1885) 
  in 
  

   the 
  Bothriocephalidae, 
  St. 
  Remy 
  (1900) 
  in 
  Anopïocephaïa 
  etc. 
  — 
  but 
  denied 
  

   by 
  St. 
  Remy 
  (1901) 
  in 
  the 
  earliest 
  stages 
  of 
  the 
  segmenting 
  egg 
  of 
  

   Taenia 
  serrata, 
  Child 
  (1907, 
  III) 
  in 
  Moniezia 
  and 
  Gough 
  (1911) 
  in 
  

   Avitellina 
  centripundata. 
  I 
  can 
  make 
  no 
  definite 
  statement 
  regarding 
  

   the 
  presence 
  of 
  a 
  shell 
  or 
  egg 
  membrane. 
  In 
  some 
  cases 
  such 
  a 
  

   structure 
  is 
  apparently 
  present 
  (Fig. 
  30), 
  in 
  others 
  absent. 
  The 
  fre- 
  

   quent 
  presence 
  of 
  sperms 
  in 
  the 
  uterus 
  wound 
  closely 
  about 
  the 
  

   ova 
  and 
  closely 
  simulating 
  a 
  definite 
  membrane 
  (compare 
  Fig. 
  30 
  

   with 
  31) 
  renders 
  a 
  positive 
  answer 
  to 
  this 
  question 
  very 
  difficult. 
  

  

  But 
  if 
  a 
  shell 
  is 
  lacking, 
  what 
  function 
  may 
  the 
  shell 
  gland 
  

   perform? 
  It 
  is 
  quite 
  possible 
  that 
  it 
  is 
  not 
  a 
  shell 
  gland 
  at 
  all, 
  but 
  

   rather 
  of 
  the 
  nature 
  of 
  a 
  prostate 
  gland 
  stimulating 
  the 
  spermatozoa 
  

   and 
  facilitating 
  fertilisation. 
  It 
  is 
  possible, 
  on 
  the 
  other 
  hand, 
  that 
  

   it 
  is 
  a 
  functionless 
  rudiment 
  of 
  the 
  functional 
  shell 
  gland 
  possessed 
  

   by 
  other 
  forms, 
  and 
  in 
  this 
  connection 
  it 
  is 
  of 
  interest 
  to 
  note 
  that 
  

  

  