﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  357 
  

  

  passing 
  from 
  its 
  point 
  of 
  union 
  with 
  the 
  terminal 
  enlargement 
  of 
  

   the 
  vagina 
  to 
  the 
  forward 
  end 
  of 
  the 
  proglottid 
  (Fig. 
  2). 
  

  

  The 
  ovary 
  arises 
  as 
  a 
  double 
  fan-shaped 
  structure 
  composed 
  of 
  

   branching 
  and 
  anastomosing 
  cell 
  cords 
  radiating 
  from 
  a 
  common 
  

   center, 
  which 
  unites 
  with 
  the 
  vagina 
  at 
  the 
  anterior 
  end 
  of 
  the 
  en- 
  

   largement 
  of 
  the 
  latter 
  (Figs. 
  2 
  and 
  3). 
  

  

  The 
  anläge 
  of 
  the 
  yolk 
  gland 
  has 
  a 
  similar 
  structure 
  to 
  that 
  

   of 
  the 
  ovary. 
  It 
  arises 
  posterior 
  to 
  the 
  enlargement 
  of 
  the 
  vagina 
  

   with 
  which 
  at 
  an 
  early 
  stage, 
  if 
  not 
  from 
  the 
  first, 
  its 
  central 
  part 
  

   is 
  united. 
  

  

  The 
  testes 
  arise 
  as 
  small 
  isolated 
  groups 
  of 
  cells 
  scattered 
  

   thru 
  the 
  parenchyma 
  peripheral 
  to 
  the 
  other 
  sex 
  organs 
  (Figs. 
  2, 
  3 
  

   and 
  4). 
  

  

  No 
  definite 
  order 
  of 
  development 
  can 
  be 
  assigned 
  to 
  the 
  various 
  

   parts 
  of 
  the 
  reproductive 
  system, 
  as 
  their 
  development 
  is 
  to 
  a 
  great 
  

   extent 
  simultaneous. 
  But 
  in 
  a 
  general 
  way 
  the 
  order 
  is 
  as 
  follows: 
  

   vas 
  deferens 
  and 
  vagina 
  first, 
  followed 
  by 
  testis, 
  ovary, 
  yolk 
  gland, 
  

   uterus 
  and 
  the 
  common 
  anläge 
  of 
  oviduct 
  and 
  shell 
  gland, 
  and 
  

   finally 
  the 
  differentiation 
  of 
  seminal 
  receptacle, 
  oviduct, 
  and 
  shell 
  

   gland. 
  The 
  various 
  genital 
  anlagen 
  arise 
  directly 
  in 
  the 
  parenchyma, 
  

   their 
  source 
  being 
  apparently 
  undifferentiated 
  cells 
  of 
  the 
  latter. 
  It 
  

   is 
  not 
  strange 
  therefore 
  that 
  one 
  finds 
  muscle 
  fibres 
  traversing 
  them 
  

   in 
  early 
  stages 
  (Figs. 
  6 
  and 
  7).^) 
  

  

  I 
  find 
  a 
  general 
  unanimity 
  in 
  the 
  literature 
  regarding 
  the 
  origin 
  

   of 
  the 
  genitalia 
  from 
  undifferentiated 
  parenchyma 
  cells, 
  but 
  as 
  to 
  

   the 
  extent 
  to 
  which 
  they 
  arise 
  independently 
  or 
  from 
  a 
  common 
  

   center 
  there 
  is 
  much 
  difference 
  of 
  opinion. 
  This 
  is 
  due 
  chiefly 
  to 
  

   the 
  delicacy 
  of 
  such 
  structures 
  as 
  the 
  vasa 
  efferentia 
  and 
  the 
  finer 
  

   branches 
  of 
  ovary 
  and 
  yolk 
  gland 
  in 
  early 
  stages, 
  and 
  their 
  lack 
  of 
  

   differentiation 
  from 
  the 
  surrounding 
  parenchyma. 
  It 
  is 
  also 
  due 
  in 
  

   part 
  to 
  the 
  rapid 
  differentiation 
  of 
  testes, 
  ovary 
  and 
  yolk 
  gland; 
  

   rendering 
  it 
  very 
  difficult 
  to 
  say 
  whether 
  they 
  are 
  differentiating 
  

   in 
  situ 
  or 
  growing 
  out 
  from 
  the 
  ends 
  of 
  their 
  respective 
  ducts. 
  My 
  

   observations 
  agree 
  with 
  those 
  of 
  Sommée 
  (1874), 
  and 
  Leuckaet 
  

   (1886) 
  on 
  Taenia 
  mediocanellata. 
  Leuckart 
  (1. 
  c.) 
  and 
  Schmidt 
  (1888) 
  

   on 
  Bothriocephalus 
  latus 
  and 
  Triaenophorus 
  nodulosiis, 
  Meyner 
  (1895) 
  

   on 
  Taenia 
  mucronata, 
  Jacobi 
  (1897) 
  on 
  Diploposthe 
  laevis, 
  etc., 
  and 
  

  

  1) 
  A 
  similar 
  observation 
  has 
  been 
  recorded 
  and 
  figured 
  by 
  Child 
  

   v(1907, 
  I) 
  in 
  the 
  ovary 
  of 
  Moniezia. 
  

  

  Zool. 
  Jahrb. 
  XXXV. 
  Abt. 
  f. 
  Anat. 
  24 
  

  

  