﻿358 
  ^- 
  T. 
  Young, 
  

  

  differ 
  from 
  those 
  of 
  Balss 
  (1908) 
  on 
  Anoplocephaïa 
  magna, 
  in 
  respect 
  

   to 
  the 
  origin 
  of 
  vagina 
  and 
  vas 
  deferens 
  from 
  a 
  common 
  anläge 
  

   rather 
  than 
  from 
  two 
  separate 
  ones. 
  The 
  last 
  author 
  has 
  suggested 
  

   that 
  a 
  difference 
  in 
  this 
  respect 
  exists 
  between 
  different 
  species. 
  I 
  

   w^ould 
  further 
  suggest 
  that 
  such 
  a 
  difference 
  may 
  exist 
  in 
  the 
  same 
  

   species, 
  and 
  even 
  in 
  different 
  proglottids 
  of 
  the 
  same 
  worm; 
  for 
  

   in 
  some 
  of 
  my 
  sections 
  I 
  find 
  variations 
  in 
  the 
  development 
  of 
  

   these 
  ducts 
  in 
  the 
  same 
  worm, 
  which 
  are 
  independent 
  of 
  the 
  age 
  of 
  

   the 
  proglottids. 
  In 
  some 
  younger 
  proglottids 
  I 
  find 
  the 
  ducts 
  

   separate, 
  while 
  in 
  other 
  older 
  ones 
  they 
  are 
  still 
  united. 
  Furthermore 
  

   the 
  length 
  of 
  the 
  anläge 
  varies 
  in 
  different 
  proglottids 
  independently 
  

   of 
  their 
  age. 
  

  

  According 
  to 
  Leuckaet 
  (1886) 
  in 
  Taenia 
  saginata 
  the 
  ovary 
  and 
  

   yolk 
  gland 
  certainly, 
  and 
  the 
  testes 
  probably 
  arise 
  from 
  the 
  common 
  

   genital 
  anläge, 
  while 
  in 
  BothriocepJialus 
  latus 
  "the 
  germ-producing 
  

   organs 
  also 
  owe 
  their 
  origins 
  to 
  the 
  cells 
  of 
  the 
  primitive 
  rudiment" 
  

   (1. 
  c, 
  p. 
  711). 
  Schmidt 
  (1888) 
  derives 
  testes, 
  yolk 
  gland, 
  and 
  prob- 
  

   ably 
  ovary 
  of 
  BothriocepJialus 
  latus 
  from 
  the 
  parenchyma 
  indepen- 
  

   dently 
  of 
  the 
  primary 
  genital 
  anläge, 
  and 
  Braun 
  (1894 
  — 
  1900, 
  

   p. 
  1604) 
  says 
  ot 
  this 
  form 
  "Unabhängig 
  von 
  diesen 
  drei 
  Canälen 
  

   legen 
  sich 
  die 
  übrigen 
  Genitalien, 
  sowohl 
  die 
  Drüsen 
  als 
  deren 
  Aus- 
  

   führungsgänge 
  an. 
  . 
  . 
  ." 
  

  

  In 
  Triaenophorus 
  nodulosus, 
  according 
  to 
  Schmidt 
  (1. 
  c), 
  part 
  

   of 
  the 
  ovary 
  arises 
  from 
  the 
  common 
  anläge 
  and 
  the 
  remainder 
  

   probably 
  independently 
  of 
  it. 
  Balss 
  (1908) 
  is 
  uncertain 
  regarding 
  

   the 
  origin 
  of 
  the 
  testes 
  of 
  Anoplocephaïa 
  7nagna, 
  but 
  (p. 
  275) 
  "Die 
  

   Ovartrauben 
  dagegen 
  entstehen 
  als 
  Sprossen 
  des 
  Oviductes." 
  Re- 
  

   garding 
  the 
  origin 
  of 
  the 
  yolk 
  gland 
  he 
  does 
  not 
  commit 
  himself. 
  

   The 
  description 
  of 
  the 
  development 
  of 
  the 
  testes 
  in 
  Momenta 
  given 
  

   by 
  Child 
  (1907, 
  II) 
  makes 
  it 
  plain 
  that 
  they 
  arise 
  independentlj^ 
  

   of 
  other 
  organs, 
  while 
  regarding 
  the 
  ovary 
  he 
  says 
  (1907, 
  I, 
  p. 
  99) 
  

   "So 
  far 
  as 
  can 
  be 
  determined 
  there 
  is 
  no 
  appreciable 
  migration 
  

   of 
  cells 
  through 
  the 
  parenchyma, 
  each 
  part 
  seems 
  to 
  be 
  formed 
  

   in 
  situ...." 
  Richards 
  (1911) 
  derives, 
  "the 
  entire 
  female 
  apparatus... 
  

   from 
  an 
  originally 
  single 
  indifferent 
  anläge". 
  

  

  My 
  own 
  observations 
  indicate 
  (altho 
  on 
  this 
  point 
  I 
  can 
  not 
  

   make 
  a 
  positive 
  statement) 
  that 
  there 
  are 
  several 
  centers 
  of 
  de- 
  

   velopment 
  in 
  the 
  genitalia. 
  I 
  find 
  for 
  example 
  in 
  one 
  specimen 
  the 
  

   anläge 
  of 
  vagina 
  and 
  vas 
  deferens 
  at 
  an 
  early 
  stage 
  of 
  develop- 
  

   ment 
  varying 
  in 
  density 
  in 
  different 
  parts 
  of 
  its 
  course, 
  as 
  tho 
  de- 
  

  

  