﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  359 
  

  

  veloping- 
  at 
  several 
  points 
  simultaneously 
  (Fig*. 
  6). 
  The 
  developini^ 
  

   uterus 
  of 
  another 
  worm 
  shows 
  variations 
  in 
  diameter 
  at 
  different 
  

   points 
  as 
  tho 
  it 
  too 
  were 
  arising 
  from 
  different 
  centers 
  {Fig. 
  8). 
  In 
  

   one 
  instance 
  I 
  find 
  a 
  vas 
  efferens 
  attached 
  to 
  two 
  testes 
  but 
  trace- 
  

   able 
  for 
  only 
  a 
  short 
  distance 
  from 
  them, 
  having 
  no 
  connection 
  

   with 
  any 
  other 
  duct. 
  Further 
  evidence 
  of 
  an 
  independent 
  origin 
  

   of 
  parts 
  is 
  found 
  in 
  the 
  fact 
  that 
  the 
  uterus 
  arises, 
  not 
  as 
  a 
  short 
  

   tongue 
  of 
  cells 
  growing 
  out 
  from 
  the 
  enlarged 
  posterior 
  end 
  of 
  the 
  

   vagina, 
  but 
  as 
  a 
  cord 
  of 
  cells 
  extending 
  from 
  the 
  first 
  thru 
  much 
  

   of 
  the 
  proglottid; 
  and 
  which 
  moreover 
  presents 
  approximately 
  the 
  

   same 
  stage 
  of 
  development 
  in 
  its 
  distal 
  as 
  in 
  its 
  proximal 
  part 
  (Fig. 
  2). 
  

   The 
  branches 
  of 
  ovary 
  and 
  yolk 
  gland 
  also, 
  from 
  their 
  first 
  appear- 
  

   ance, 
  are 
  approximately 
  uniform 
  in 
  their 
  development 
  thruout, 
  as 
  

   one 
  would 
  expect 
  if 
  they 
  arose 
  simultaneously 
  at 
  all 
  points, 
  but 
  not 
  

   if 
  they 
  originated 
  as 
  outgrowths 
  from 
  an 
  earlier 
  anläge 
  (Fig. 
  9). 
  This 
  

   method 
  moreover 
  is 
  analogous 
  to 
  that 
  described 
  by 
  me 
  (Young, 
  

   1908) 
  in 
  Cysticercus 
  pisiformis, 
  where 
  I 
  found 
  the 
  various 
  organs 
  

   developing 
  in 
  situ 
  thruout, 
  rather 
  than 
  growing 
  out 
  from 
  a 
  common 
  

   center.^) 
  

  

  The 
  development 
  of 
  the 
  wall 
  of 
  all 
  the 
  larger 
  reproductive 
  

   ducts 
  is 
  similar, 
  consisting 
  in 
  the 
  hollowing 
  out 
  of 
  a 
  solid 
  cord 
  of 
  

   cells 
  and 
  its 
  diiferentiation 
  into 
  two 
  layers, 
  between 
  which 
  a 
  basement 
  

   membrane 
  is 
  formed 
  by 
  a 
  condensation 
  of 
  fibrillae. 
  Surrounding 
  this 
  

   membrane 
  a 
  layer 
  of 
  delicate, 
  scattered 
  muscle 
  fibres, 
  the 
  extent 
  of 
  

   development 
  of 
  which 
  varies 
  in 
  different 
  parts 
  of 
  the 
  duct 
  system, 
  

   is 
  formed 
  directly 
  from 
  the 
  fibrillae 
  of 
  the 
  anläge. 
  The 
  inner, 
  

   epithelial 
  layer 
  consists 
  of 
  a 
  row 
  of 
  cells, 
  varying 
  in 
  height 
  in 
  

   different 
  ducts, 
  their 
  fate 
  also 
  depending 
  on 
  the 
  place 
  where 
  they 
  

   occur. 
  The 
  outer 
  layer 
  likewise 
  varies 
  in 
  different 
  regions 
  both 
  as 
  

   to 
  number 
  and 
  form 
  of 
  cells 
  composing 
  it. 
  

  

  Cytological 
  conditions 
  in 
  the 
  developing 
  ducts 
  are 
  similar 
  to 
  

   those 
  described 
  by 
  me 
  in 
  this 
  and 
  other 
  cestodes 
  (Young, 
  1910), 
  the 
  

   anläge 
  of 
  the 
  ducts 
  consisting 
  of 
  a 
  dense 
  fibrillar 
  mass 
  in 
  which 
  are 
  

   imbedded 
  the 
  granular 
  masses 
  representing 
  the 
  nuclei 
  (Figs. 
  6 
  and 
  7). 
  

   These 
  vary 
  in 
  size, 
  shape, 
  and 
  definiteness. 
  In 
  some 
  cases 
  the 
  chro- 
  

   matin 
  is 
  distributed 
  thruout 
  the 
  nucleus 
  and 
  in 
  others 
  limited 
  to 
  

   one 
  or 
  more 
  definite 
  masses. 
  Some 
  nuclei 
  consist 
  of 
  membranes 
  only, 
  

  

  1) 
  Concerning 
  the 
  nerves 
  I 
  could 
  not 
  be 
  entirely 
  positive, 
  altho 
  this 
  

   mode 
  of 
  development 
  seemed 
  most 
  probable 
  for 
  them 
  also. 
  

  

  24* 
  

  

  