﻿366 
  R- 
  T. 
  Young, 
  

  

  be 
  equally 
  well 
  developed, 
  or 
  one 
  or 
  the 
  other 
  may 
  predominate, 
  

   while 
  in 
  some 
  cases 
  only 
  one 
  is 
  present. 
  They 
  may 
  vary 
  in 
  size 
  

   moreover 
  in 
  different 
  parts 
  of 
  the 
  penis 
  sheath. 
  According 
  to 
  

   LÖNNBERG 
  (1892) 
  in 
  Diplogonoporus 
  halaenopterae, 
  Steudener 
  (1877) 
  

   in 
  Taenia 
  tripunctata 
  and 
  Roboz 
  (1882) 
  in 
  SolenopJiorus 
  megalocephalus 
  

   radial 
  muscles 
  occur 
  within 
  the 
  penis 
  sheath. 
  

  

  Genital 
  atrium. 
  As 
  already 
  stated, 
  there 
  is 
  no 
  ingrowth 
  

   of 
  sub-cuticular 
  cells 
  to 
  meet 
  the 
  outgrowing 
  duct 
  anläge. 
  After 
  

   the 
  latter 
  reaches 
  the 
  periphery 
  however 
  there 
  is 
  an 
  invagination 
  

   of 
  the 
  surface 
  to 
  meet 
  it, 
  which, 
  growing 
  into 
  the 
  proglottid 
  and 
  

   receiving 
  the 
  openings 
  of 
  vagina 
  and 
  penis 
  as 
  these 
  latter 
  develop, 
  

   forms 
  the 
  atrium 
  (Fig. 
  5). 
  It 
  is 
  lined 
  by 
  the 
  non-ciliate 
  cuticula 
  of 
  

   the 
  general 
  body 
  surface, 
  which 
  becomes 
  continuous 
  with 
  the 
  ciliate 
  

   cuticula 
  of 
  the 
  ducts 
  near 
  their 
  point 
  of 
  opening.^) 
  A 
  specialized 
  

   musculature 
  is 
  lacking, 
  but 
  dorsally 
  and 
  ventrally 
  the 
  transverse 
  

   muscles 
  of 
  the 
  proglottid 
  are 
  strengthened 
  and 
  somewhat 
  crowded 
  

   out 
  of 
  their 
  usual 
  position 
  by 
  the 
  atrium, 
  forming 
  poorly 
  marked 
  

   segments 
  of 
  a 
  cylinder 
  above 
  and 
  below 
  the 
  latter 
  (Fig. 
  5). 
  This 
  

   condition 
  is 
  similar 
  to 
  that 
  described 
  by 
  Sommée 
  (1874) 
  in 
  Taenia 
  

   mediocanellata 
  and 
  soliufn. 
  

  

  The 
  account 
  of 
  the 
  origin 
  of 
  the 
  atrium 
  which 
  is 
  found 
  in 
  the 
  

   literature 
  is 
  a 
  varied 
  one. 
  Kahane 
  (1880), 
  Kraemer 
  (1892), 
  Lung- 
  

   wiTz 
  (1895), 
  etc. 
  derive 
  it 
  from 
  an 
  invagination 
  of 
  the 
  body 
  surface 
  ; 
  

   while 
  according 
  to 
  Jacobi 
  (1897), 
  in 
  DiplopostJie 
  laevis, 
  Wolf- 
  

   hügel 
  (1900) 
  in 
  Fimhriaria 
  fasciolaris, 
  and 
  Balss 
  (1908) 
  in 
  Anoplo- 
  

   cephala 
  magna 
  it 
  arises 
  at 
  first 
  as 
  a 
  closed 
  sack 
  from 
  a 
  mass 
  of 
  

   cells 
  extending 
  from 
  the 
  vagina 
  and 
  vas 
  deferens 
  to 
  the 
  surface.^) 
  

   My 
  own 
  observations 
  thus 
  agree 
  with 
  those 
  of 
  the 
  former 
  authors. 
  

  

  The 
  oviduct^) 
  develops 
  from 
  an 
  anläge 
  common 
  to 
  its 
  major 
  

  

  1) 
  See 
  page 
  363. 
  Erlanger 
  (1890) 
  is 
  the 
  only 
  author, 
  who 
  to 
  my 
  

   knowledge 
  describes 
  hairs 
  or 
  cilia 
  in 
  the 
  genital 
  atrium. 
  

  

  2) 
  Balss' 
  statements 
  are 
  not 
  entirely 
  clear 
  on 
  this 
  point. 
  He 
  says 
  

   (1. 
  c, 
  p. 
  276) 
  "Hier 
  münden 
  . 
  . 
  . 
  Cirrus 
  und 
  Vagina 
  bereits 
  im 
  Innern 
  

   des 
  Bandwurmkörpers 
  in 
  eine 
  . 
  . 
  . 
  Blase, 
  und 
  vor 
  dieser, 
  dem 
  Seiten- 
  

   rande 
  zu, 
  bildet 
  sich 
  ein 
  Strang 
  von 
  dicht 
  aneinander 
  gelagerten 
  Parenchym- 
  

   zellen." 
  The 
  origin 
  of 
  this 
  bladder 
  is 
  not 
  described. 
  Presumably 
  it 
  

   arises 
  by 
  a 
  hollowing 
  out 
  of 
  this 
  cord 
  of 
  cells. 
  

  

  3) 
  Solely 
  as 
  a 
  matter 
  of 
  convenience 
  in 
  discussing 
  its 
  development 
  

   and 
  without 
  reference 
  to 
  the 
  homology 
  of 
  its 
  parts 
  , 
  I 
  have 
  applied 
  

   the 
  term 
  „oviduct" 
  to 
  the 
  duct 
  leading 
  from 
  the 
  seminal 
  receptacle 
  to 
  the 
  

   uterus, 
  including 
  the 
  branch 
  to 
  the 
  ovaries. 
  For 
  a 
  discussion 
  of 
  the 
  

  

  