﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  389 
  

  

  diifers 
  however 
  in 
  the 
  absence 
  of 
  the 
  periods 
  of 
  growth 
  and 
  abortive 
  

   maturation 
  which 
  occur 
  in 
  the 
  development 
  of 
  the 
  latter. 
  

  

  The 
  determination 
  of 
  the 
  method 
  of 
  yolk 
  formation 
  is 
  rendered 
  

   difficult 
  by 
  the 
  closely 
  packed 
  condition 
  of 
  the 
  yolk 
  cells 
  at 
  this 
  

   time, 
  so 
  that 
  their 
  boundaries 
  are 
  difficult 
  to 
  see. 
  Apparently 
  it 
  

   is 
  laid 
  down 
  as 
  a 
  single 
  mass 
  in 
  most 
  cases, 
  but 
  in 
  some 
  at 
  least 
  

   as 
  more 
  than 
  one, 
  which 
  later 
  fuse 
  to 
  form 
  the 
  spherical 
  yolk 
  mass 
  

   of 
  the 
  adult 
  cell 
  (Figs. 
  57 
  and 
  58). 
  During 
  yolk 
  formation 
  the 
  cells, 
  

   but 
  not 
  the 
  nuclei, 
  increase 
  in 
  size.^j 
  

  

  In 
  respect 
  to 
  the 
  structure 
  of 
  the 
  follicular 
  membrane 
  there 
  

   IS 
  the 
  same 
  divergence 
  of 
  opinion 
  as 
  already 
  noted 
  regarding 
  testis 
  and 
  

   •ovary. 
  Here 
  as 
  there 
  the 
  difference 
  may 
  be 
  due 
  to 
  imperfection 
  of 
  

   technique, 
  or 
  inaccuracy 
  of 
  observation 
  in 
  dealing 
  with 
  such 
  delicate 
  

   structures. 
  It 
  may 
  on 
  the 
  contrary 
  however 
  be 
  due 
  to 
  actual 
  dif- 
  

   ference 
  in 
  structure 
  of 
  different 
  species. 
  

  

  Further 
  history 
  of 
  the 
  sex 
  cells. 
  After 
  the 
  growth 
  

   period 
  with 
  its 
  coincident 
  reconstitution 
  of 
  the 
  egg 
  nucleus 
  and 
  

   yolk 
  deposition, 
  the 
  oocyte 
  passes 
  thru 
  the 
  oviduct 
  to 
  the 
  uterus. 
  

   During, 
  or 
  following 
  this 
  period 
  the 
  egg 
  undergoes 
  an 
  abortive 
  

   maturation 
  division 
  and 
  is 
  fertilized. 
  

  

  The 
  first 
  stages 
  in 
  the 
  abortive 
  maturation 
  mitosis, 
  which 
  I 
  

   l)elieve 
  represents 
  the 
  second 
  division 
  of 
  typical 
  maturation, 
  may 
  

   occur 
  in 
  the 
  ovary. 
  Usually 
  however 
  I 
  believe 
  that 
  they 
  do 
  not 
  

   occur 
  until 
  the 
  egg 
  reaches 
  the 
  oviduct 
  or 
  the 
  uterus, 
  for 
  their 
  

   •occurrence 
  in 
  the 
  ovary 
  is 
  very 
  rare 
  and 
  frequently 
  cells 
  resembling 
  

   in 
  every 
  way 
  the 
  ovarian 
  oocytes 
  are 
  present 
  in 
  the 
  uterus. 
  The 
  

   earliest 
  stage 
  observed 
  was 
  in 
  an 
  oocyte 
  just 
  passing 
  from 
  an 
  oviduct 
  

   branch 
  into 
  the 
  main 
  duct. 
  In 
  this 
  oocyte 
  a 
  single 
  distinct 
  aster 
  

   had 
  formed 
  on 
  the 
  border 
  of 
  the 
  nucleus 
  so 
  that 
  it 
  was 
  impossible 
  

   to 
  say 
  whether 
  it 
  had 
  arisen 
  in 
  the 
  latter 
  or 
  in 
  the 
  cytoplasm. 
  

   I 
  believe 
  that 
  the 
  latter 
  is 
  the 
  case 
  because 
  a 
  centrosome 
  is 
  absent 
  ^), 
  

   and 
  the 
  aster 
  is 
  composed 
  of 
  rays 
  which 
  are 
  clearly 
  continuous 
  

   with 
  the 
  strands 
  of 
  the 
  cytoplasm. 
  A 
  centrosome 
  being 
  absent 
  

   there 
  is 
  no 
  definite 
  center 
  which 
  could 
  have 
  arisen 
  in 
  the 
  nucleus, 
  

  

  1) 
  From 
  9,4^4,8 
  ju 
  to 
  10,4X9,4, 
  average 
  of 
  10 
  measurements 
  in 
  

   •each 
  case. 
  

  

  2) 
  The 
  so-called 
  "centrosome" 
  is 
  nothing 
  I 
  believe 
  more 
  than 
  the 
  central 
  

   -dense 
  massing 
  of 
  the 
  astral 
  rays. 
  

  

  Zool. 
  Jahrb. 
  XXXV. 
  Abt. 
  f. 
  Anat. 
  26 
  

  

  