﻿Reproductive 
  organs 
  of 
  Taenia 
  pisiformis. 
  407 
  

  

  follows 
  the 
  nuclear 
  division; 
  and 
  3. 
  that 
  the 
  descendants 
  of 
  amitotic 
  

   division 
  shall 
  again 
  divide 
  by 
  mitosis 
  with 
  the 
  normal 
  chromosome 
  

   number. 
  A 
  positive 
  demonstration 
  of 
  any 
  one 
  of 
  these 
  points 
  is 
  

   apparently 
  impossible 
  in 
  fixed 
  material, 
  which 
  is 
  probably 
  the 
  only 
  

   kind 
  of 
  cestode 
  tissue 
  available 
  for 
  study. 
  ^) 
  An 
  unbiassed 
  conside- 
  

   ration 
  of 
  Figs. 
  35, 
  37, 
  38 
  and 
  40 
  will 
  however 
  I 
  believe 
  dispel 
  any 
  

   reasonable 
  doubt 
  on 
  the 
  first 
  two 
  of 
  these 
  points. 
  Eegarding 
  the 
  

   third 
  there 
  is 
  no 
  possibility 
  of 
  tracing 
  the 
  history 
  of 
  any 
  individual 
  

   cell, 
  but 
  the 
  unquestionable 
  occurrence 
  of 
  numerous 
  prophases 
  at 
  a 
  

   slightly 
  later 
  stage 
  of 
  spermatogenesis 
  renders 
  it 
  highly 
  probable 
  that 
  

   descendants 
  of 
  cells 
  which 
  have 
  divided 
  amitotically 
  at 
  an 
  earlier 
  

   stage 
  do 
  experience 
  at 
  least 
  an 
  abortive 
  mitosis 
  at 
  a 
  later 
  one. 
  

  

  Concerning 
  the 
  nature 
  of 
  the 
  "nucleolus" 
  which 
  I 
  have 
  held 
  to 
  

   be 
  a 
  caryosome 
  and 
  not 
  a 
  true 
  nucleolus^), 
  I 
  can 
  add 
  little 
  to 
  the 
  

   evidence 
  given 
  in 
  my 
  former 
  papers. 
  I 
  have 
  not 
  used 
  the 
  Flemming 
  

   triple 
  stain 
  which 
  Richards 
  employed 
  and 
  my 
  differential 
  stains 
  

   (methyl 
  green 
  and 
  acid 
  fuchsin) 
  and 
  microchemical 
  tests 
  do 
  not 
  bear 
  

   out 
  his 
  contention 
  that 
  this 
  structure 
  is 
  a 
  true 
  nucleolus. 
  I 
  have 
  

   seen 
  possibly 
  similar 
  appearances 
  to 
  those 
  described 
  by 
  him 
  in 
  the 
  

   "nucleoli" 
  of 
  Crossobothrium 
  laciniatum 
  but 
  suspect 
  that 
  they 
  may 
  be 
  

   due 
  to 
  lack 
  of 
  homogeneity. 
  Richards 
  (1. 
  c, 
  p. 
  143) 
  mentions 
  the 
  

   occasional 
  occurrence 
  of 
  "several 
  vacuoles" 
  in 
  the 
  "nucleoli" 
  of 
  Monie^ia 
  

   and 
  states 
  further 
  that 
  the 
  latter 
  "may 
  well 
  serve 
  as 
  chromatin 
  

   reservoirs 
  during 
  the 
  resting 
  period 
  of 
  the 
  nucleus. 
  . 
  . 
  . 
  Furthermore 
  

   the 
  nucleoli 
  are 
  always 
  in 
  intimate 
  connection 
  with 
  the 
  spireme 
  . 
  . 
  ." 
  

   If 
  I 
  interpret 
  Richards' 
  figures 
  aright^), 
  the 
  major 
  part 
  of 
  his 
  

   "nucleoli" 
  consists 
  of 
  a 
  substance 
  which 
  "stains 
  with 
  gentian 
  violet 
  

   just 
  as 
  does 
  chromatin, 
  and 
  the 
  darker 
  bodies 
  (contained 
  within 
  this 
  

   peripheral 
  portion) 
  easily 
  suggest 
  chromatin 
  masses". 
  Within 
  the 
  

   relatively 
  small 
  "vacuole", 
  or 
  one 
  of 
  these, 
  there 
  appears 
  during 
  the 
  

   growth 
  period 
  "the 
  endonucleolus 
  staining 
  very 
  dark 
  with 
  gentian 
  

   violet 
  (and) 
  a 
  reticulum 
  supporting 
  this 
  body". 
  His 
  description 
  and 
  figures 
  

   suggest 
  a 
  non-homogeneous 
  chromatin 
  mass 
  containing 
  "vacuoles" 
  

   which 
  stain 
  with 
  safranin. 
  His 
  account 
  fails 
  to 
  state 
  how 
  the 
  cyto- 
  

  

  1) 
  Morse 
  (1911) 
  is 
  the 
  only 
  author 
  I 
  know 
  of 
  who 
  has 
  endeavored 
  

   to 
  study 
  this 
  question 
  in 
  living 
  cestode 
  tissue, 
  and 
  his 
  attempt 
  did 
  not 
  

   meet 
  with 
  success. 
  

  

  2) 
  Young 
  (1908, 
  1910). 
  

  

  3) 
  The 
  various 
  structures 
  described 
  in 
  the 
  text 
  are 
  not 
  labeled 
  in 
  

   the 
  figures. 
  

  

  27* 
  

  

  