﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  403 
  

  

  'Here 
  as 
  in 
  the 
  development 
  of 
  the 
  female 
  organs, 
  it 
  is 
  difficult 
  to 
  

   resist 
  the 
  impression 
  that 
  the 
  development 
  of 
  these 
  organs 
  is 
  the 
  

   result 
  of 
  some 
  localized 
  stimulus 
  or 
  condition 
  and 
  that 
  any 
  cells 
  

   within 
  reach 
  of 
  this 
  factor 
  may 
  become 
  involved," 
  (1907, 
  II, 
  

   p. 
  177). 
  

  

  The 
  epithelial 
  question. 
  Regarding 
  the 
  structure 
  of 
  

   the 
  reproductive 
  ducts 
  and 
  its 
  bearing 
  on 
  the 
  epithelial 
  question, 
  

   we 
  have 
  seen 
  that 
  while 
  all 
  of 
  these 
  ducts 
  possess 
  an 
  epithelium 
  

   at 
  some 
  stage 
  of 
  their 
  development, 
  this 
  may 
  or 
  may 
  not 
  persist 
  in 
  

   the 
  fully 
  formed 
  duct. 
  In 
  vagina, 
  and 
  penis 
  the 
  epithelium 
  is 
  

   changed 
  to 
  a 
  cuticula. 
  A 
  similar 
  process 
  has 
  been 
  described 
  

   by 
  ZiEGLEE 
  (1883) 
  in 
  Bucephalus 
  (Gasterostommn), 
  Schauinsland 
  

   (1883) 
  in 
  Distomum 
  tereticoUe, 
  Leuckart 
  (1886) 
  in 
  Fasciola 
  hepaticay 
  

   etc. 
  Several 
  writers 
  ^) 
  claim 
  to 
  have 
  found 
  nucle 
  in 
  the 
  trematode 
  

   cuticle. 
  This 
  claim 
  has 
  been 
  disputed 
  by 
  Looss 
  (1893) 
  and 
  

   Blochmann 
  (1896), 
  who 
  hold 
  that 
  these 
  supposed 
  nuclei 
  are 
  

   either 
  artifacts 
  or 
  the 
  endings 
  of 
  sense 
  cells. 
  While 
  I 
  have 
  not 
  

   found 
  nuclei 
  in 
  the 
  outer 
  cuticula 
  of 
  Taenia 
  pisiformis 
  my 
  Figs. 
  12—14 
  

   prove 
  conclusively 
  their 
  presence 
  in 
  the 
  developing 
  cuticula 
  of 
  the 
  

   reproductive 
  ducts 
  in 
  this 
  form, 
  and 
  its 
  development 
  is 
  here 
  clearly 
  

   shown 
  to 
  be 
  a 
  metamorphosis 
  of 
  an 
  epithelium. 
  Balss 
  (1908) 
  has 
  

   shown 
  this 
  process 
  very 
  clearly 
  in 
  his 
  Figs. 
  11, 
  12, 
  and 
  13, 
  but 
  

   interprets 
  his 
  observations 
  differently. 
  He 
  says 
  (1. 
  c, 
  p. 
  277) 
  

   "\¥ährend 
  hier 
  nun 
  die 
  Kerne 
  degenerieren 
  und 
  ihre 
  Substanz 
  von 
  

   Plasma 
  wohl 
  resorbiert 
  wird 
  ... 
  die 
  umgebenden 
  Parenchymzellen 
  . 
  . 
  . 
  

   die 
  Cuticula 
  abscheiden." 
  Similar 
  views 
  have 
  been 
  expressed 
  by 
  

   Leuckart 
  (1886), 
  Ziegler 
  (1905), 
  etc. 
  To 
  prove 
  this 
  view 
  would 
  

   be 
  difficult. 
  The 
  appearance 
  produced 
  by 
  an 
  epithelium 
  in 
  process 
  

   of 
  absorption 
  with 
  simultaneous 
  elaboration 
  of 
  a 
  cuticula 
  by 
  the 
  

   underlying 
  parenchyma 
  would 
  probably 
  not 
  differ 
  widely 
  from 
  that 
  

   of 
  an 
  epithelial 
  metamorphosis. 
  If 
  however 
  the 
  formation 
  of 
  the 
  

   cuticula 
  did 
  not 
  occur 
  until 
  after 
  the 
  disappearance 
  of 
  the 
  epithelium, 
  

   a 
  stage 
  should 
  intervene 
  in 
  which 
  neither 
  is 
  present. 
  There 
  is 
  no 
  

   such 
  stage 
  in 
  Taenia 
  pisiformis. 
  I 
  have 
  traced 
  moreover 
  the 
  gradual 
  

   transition 
  from 
  a 
  nucleated 
  epithelium 
  in 
  one 
  part 
  to 
  a 
  ciliate 
  

   cuticula 
  in 
  another, 
  in 
  both 
  vagina 
  and 
  penis 
  at 
  one 
  stage 
  of 
  

   development, 
  the 
  former 
  being 
  replaced 
  later 
  by 
  the 
  latter. 
  The 
  gradual 
  

  

  1) 
  Braun 
  (1893) 
  in 
  Monostomum 
  mutahile, 
  Nickerson 
  (1902) 
  in 
  

   Gotylogaster 
  occidentalism 
  MacLAEEN 
  (1903) 
  in 
  Distomum 
  sp. 
  etc. 
  

  

  