﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  373 
  

  

  lack 
  however 
  definite 
  outlines 
  no 
  membrane 
  being 
  presents) 
  The 
  

   chromatin 
  masses 
  appear 
  on 
  the 
  contrary 
  to 
  be 
  laid 
  down 
  in 
  the 
  

   cytoplasm 
  and 
  supported 
  by 
  its 
  strands. 
  The 
  nuclear 
  areas 
  thus 
  

   formed 
  stain 
  lighter 
  (between 
  the 
  chromatin 
  bodies) 
  than 
  the 
  sur- 
  

   rounding 
  cytoplasm, 
  due 
  I 
  believe 
  to 
  their 
  lesser 
  density. 
  True 
  

   nucleoli 
  are 
  apparently 
  absent 
  (Figs. 
  35 
  — 
  40). 
  

  

  Here 
  as 
  in 
  other 
  cestode 
  tissues 
  the 
  method 
  of 
  cell 
  increase 
  is 
  

   difficult 
  to 
  determine. 
  Mitosis 
  is 
  apparently 
  absent. 
  I 
  have 
  counted 
  

   over 
  2800 
  cells 
  -) 
  in 
  the 
  early 
  testes 
  without 
  finding 
  a 
  single 
  instance. 
  

   There 
  remain 
  then 
  three 
  possibilities, 
  — 
  amitosis 
  ^}, 
  de 
  novo 
  develop- 
  

   ment 
  and 
  development 
  from 
  chromidial 
  extrusions 
  from 
  préexistent 
  

   nuclei. 
  A 
  positive 
  diagnosis 
  of 
  amitosis 
  is, 
  as 
  Richards 
  (1911, 
  p. 
  124) 
  

   iias 
  well 
  said, 
  "difficult 
  to 
  obtain. 
  One 
  cannot 
  always 
  be 
  sure 
  that 
  

   a 
  nuclear 
  constriction 
  is 
  not 
  a 
  product 
  of 
  mechanical 
  compression, 
  

   ■e. 
  g., 
  by 
  yolk 
  granules, 
  or 
  an 
  artifact 
  due 
  to 
  reagents 
  rather 
  than 
  

   ^ 
  stage 
  in 
  division. 
  A 
  strand 
  of 
  linin 
  stretched 
  across 
  a 
  nucleus 
  

   with 
  chromatin 
  granules 
  upon 
  it 
  often 
  gives 
  the 
  appearance 
  of 
  a 
  

   membrane 
  dividing 
  the 
  nucleus 
  amitotically 
  (endogenous 
  division?). 
  

   Nuclear 
  lobations 
  are 
  frequently 
  seen 
  in 
  cells 
  which 
  are 
  known 
  to 
  

   multiply 
  by 
  mitosis. 
  Finally 
  a 
  reduplication 
  of 
  nuclei 
  for 
  any 
  of 
  

   several 
  reasons 
  — 
  disintegration, 
  accessory 
  sperm 
  nuclei 
  in 
  egg 
  cells, 
  

   the 
  male 
  and 
  female 
  pronuclei 
  themselves, 
  lagging 
  of 
  cytoplasmic 
  

   division 
  behind 
  nuclear 
  mitosis, 
  incompletely 
  fused 
  chromosomal 
  ves- 
  

   €icles, 
  etc. 
  easily 
  presents 
  a 
  simulacrum 
  of 
  amitosis 
  which 
  is 
  quite 
  

   misleading." 
  In 
  most 
  of 
  the 
  testes 
  studied 
  by 
  me 
  the 
  evidence 
  

   of 
  amitosis 
  is 
  not 
  conclusive. 
  Occasional 
  instances 
  of 
  constricted 
  

   nuclei 
  and 
  of 
  binucleate 
  cells 
  do 
  indeed 
  occur. 
  But 
  this 
  is 
  not 
  

   entirely 
  convincing 
  evidence. 
  I 
  have 
  found 
  and 
  photographed 
  

   (Figs. 
  35, 
  37, 
  38, 
  40) 
  however 
  a 
  few 
  cases 
  which 
  in 
  my 
  opinion 
  aftbrd 
  

   very 
  strong 
  evidence 
  of 
  this 
  process. 
  In 
  Fig. 
  35 
  is 
  shown 
  a 
  spermato- 
  

   gonium 
  with 
  a 
  deep 
  indentation 
  in 
  one 
  side, 
  this 
  indentation 
  affect- 
  

   ing 
  both 
  cytoplasm 
  and 
  nucleus. 
  A 
  slight 
  constriction 
  appears 
  on 
  

   the 
  opposite 
  side, 
  the 
  division 
  thus 
  being 
  more 
  than 
  half 
  completed. 
  

   Either 
  half 
  of 
  the 
  nucleus 
  consists 
  of 
  a 
  large 
  mass 
  of 
  chromatin 
  

   with 
  a 
  few 
  smaller 
  masses. 
  One 
  of 
  the 
  daughter 
  cells 
  already 
  be- 
  

  

  1) 
  A 
  consideration 
  of 
  the 
  nuclear 
  membrane 
  will 
  be 
  taken 
  up 
  later 
  

   (page 
  406). 
  See 
  also 
  page 
  375, 
  foot 
  note. 
  

  

  2) 
  The 
  total 
  number 
  of 
  cells 
  examined 
  is 
  much 
  greater 
  than 
  this. 
  

  

  3) 
  In 
  the 
  ordinary 
  sense 
  of 
  that 
  term. 
  

  

  Zool. 
  Jahrb. 
  XXXV. 
  Abt. 
  f. 
  Anat. 
  25 
  

  

  