﻿378 
  E- 
  T. 
  Young, 
  

  

  fact 
  that 
  thej' 
  appear 
  coincidently 
  with 
  the 
  disappearance 
  of 
  the 
  

   skeins 
  and 
  the 
  appearance 
  of 
  skein 
  rudiments 
  in 
  the 
  cytophore^ 
  

   Fig. 
  51 
  sJc, 
  renders 
  it 
  highly 
  probable 
  that 
  they 
  arise 
  from 
  these 
  

   rudiments. 
  If 
  this 
  be 
  true 
  their 
  origin 
  is 
  similar 
  to 
  that 
  of 
  many 
  

   of 
  the 
  spermatogonia 
  described 
  above. 
  

  

  The 
  further 
  course 
  of 
  spermatogenesis 
  in 
  Taenia 
  pisiformis 
  is 
  

   uncertain. 
  In 
  my 
  preliminary 
  account 
  (Young, 
  1912 
  a) 
  I 
  have 
  stated 
  

   that 
  the 
  second 
  spermatocytes 
  break 
  down 
  in 
  the 
  cytophore 
  while 
  

   the 
  spermatozoa 
  are 
  formed 
  from 
  the 
  fibrillae 
  of 
  the 
  latter. 
  My 
  

   evidence 
  for 
  this 
  is 
  the 
  disappearance 
  of 
  the 
  former 
  combined 
  with 
  

   the 
  fact 
  that 
  the 
  spermatozoa 
  develop 
  peripherally 
  to 
  the 
  cytophore, 
  

   and 
  that 
  with 
  their 
  appearance 
  the 
  latter 
  in 
  large 
  part 
  disappears 
  

   (Fig. 
  51). 
  A 
  careful 
  comparison 
  of 
  a 
  mass 
  of 
  developing 
  sperms 
  ad- 
  

   joining 
  a 
  cytophore 
  shows 
  no 
  line 
  of 
  demarcation 
  between 
  the 
  two, 
  

   the 
  former 
  passing 
  insensibly 
  over 
  into 
  the 
  latter. 
  In 
  several 
  cases 
  

   I 
  have 
  traced 
  an 
  apparent 
  connection 
  between 
  sperms 
  and 
  

   ■cytophore 
  fibrillae. 
  In 
  Fig. 
  47 
  ^) 
  is 
  shown 
  a 
  degenerating 
  first 
  

   spermatocyte 
  to 
  the 
  network 
  of 
  which 
  is 
  directly 
  attached 
  a 
  sperm 
  

   at 
  X. 
  In 
  most 
  cases 
  the 
  first 
  spermatocytes 
  break 
  down 
  completely 
  

   distributing 
  their 
  skein 
  fragments 
  thru 
  the 
  cytoplasm 
  of 
  the 
  

   cytophore, 
  the 
  fibrillae 
  of 
  the 
  latter 
  then 
  giving 
  rise 
  to 
  the 
  sperms. 
  

   Here 
  however 
  can 
  be 
  seen 
  clearly 
  the 
  direct 
  connection 
  between 
  

   spermatocyte 
  skein 
  and 
  developing 
  sperm, 
  before 
  the 
  complete 
  de- 
  

   generation 
  of 
  the 
  former. 
  This 
  suggests 
  a 
  probable 
  chromatic 
  origin 
  

   of 
  all 
  sperms, 
  even 
  tho 
  in 
  most 
  cases 
  such 
  an 
  origin 
  is 
  indirect, 
  thru 
  

   the 
  fibrillae 
  of 
  the 
  cytophore 
  from 
  chromatin 
  fragments 
  scattered 
  

   thru 
  the 
  latter. 
  

  

  Such 
  an 
  origin 
  is 
  shown 
  in 
  Fig. 
  50 
  where 
  may 
  be 
  seen 
  several 
  

   chromatin 
  granules 
  scattered 
  thru 
  a 
  cytophore. 
  These 
  are 
  probably 
  

   the 
  "nucleoli" 
  of 
  second 
  spermatocytes 
  which 
  have 
  partly 
  degener- 
  

   ated, 
  the 
  "nucleoli" 
  alone 
  persisting. 
  At 
  ^ 
  are 
  show^n 
  two 
  sperms 
  

   crossing 
  each 
  other, 
  one 
  of 
  which 
  is 
  seen 
  terminating 
  in 
  a 
  chromatin 
  

   granule 
  while 
  the 
  other 
  terminates 
  similarly, 
  altho 
  this 
  is 
  not 
  shown 
  

   in 
  the 
  photograph 
  since 
  one 
  granule 
  lies 
  at 
  a 
  slightly 
  different 
  

   focal 
  level. 
  

  

  In 
  a 
  few 
  cases 
  I 
  find 
  a 
  direct 
  connection 
  between 
  sperms 
  and 
  

   second 
  spermatocytes. 
  In 
  Fig. 
  45 
  is 
  shown 
  an 
  early 
  stage 
  in 
  sperm 
  

   development, 
  the 
  latter 
  appearing 
  as 
  a 
  very 
  delicate 
  filament 
  sp 
  

  

  1) 
  J^^ig. 
  47 
  is 
  the 
  same 
  as 
  Fig. 
  51 
  sä; 
  at 
  a 
  slightly 
  different 
  focal 
  level. 
  

  

  