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development  takes  place  by  means  of  the  activity  of  the  ependyma 
and  to  a subordinate  and  liinited  extent  by  means  of  direct  division. 
Where  Uiese  elements  exist  they  sink  down  and  gradually  disappear, 
sending  off  a first  process,  which  grows  and  is  lengthened,  wliile 
otliei’S  are  also  developed,  so  tliat  gradually  a mnltipolar  cell  arises. 
“Avant  d’arriver  a cette  différenciation,  ces  cléments  se  divisent  ^a 
et  la  par  scission  directe,  qni,  on  bien  se  compléte  — et  alors  les 
nonveanx  éléments  restent  en  connexion  avec  un  des  prolongemenis 
— on  bien  ne  s’achève  pas,  et  on  a alors  des  formations  gemellaires 
de  divers  degré.  Ces  faits  peuvent  s’observer  Ie  long  de  la  moelle 
épinière  d’individns  d’age  différent  et  dans  des  préparations  obtennes 
avec  des  séries  de  sections  frontales  et  avec  les  divers  colorations”. 
Pai-adino  accompanies  his  statement  witli  a figure  to  show  how  the 
epithelinm-cells  (ependyma)  are  fnrtlier  differentiated  and  move  down 
into  the  snrrounding  tissue.  On  the  other  hand  it  is  to  be  regretted 
that  P.  did  not  add  a fignre  showing  a cell  engaged  in  direct  division 
and  that  he  did  not  give  a more  detailed  description  of  the  amitoses 
in  the  central  nervoiis  System  observed  by  him. 
The  more  thoronghly  I stndy  my  prepai-ations  from  the  centi-al 
nervons  system  of  animals  of  varions  post-embryonic  ages,  the  more 
convinced  am  I that  Paladino  is  right  in  his  statements  as  given 
above.  In  these  préparations  of  mine  I have  fonnd,  in  a nnmber 
of  places,  appearances  that  indicate,  jnst  as  clearly  as  P.’s  figure,  a 
movement  of  cells  from  the  ependyma  into  the  snri'onnding  tissue.  These 
appearances  are  not,  howevei',  fonnd  continnonsly  along  the  whole 
central  canal  but  occnr  scattered  here  and  there  — this  too  agrees  with 
P.’s  statements.  On  the  other  hand,  with  regard  to  tigures  of  direct 
cell  division,  I have  observed  a large  nnmber  which,  in  my  opinion, 
are  to  be  interpreted  in  this  way.  And  as  a matter  of  fact  1 have 
obtained  series  of  snch  appearances  which  show  the  different  stages 
of  a direct  cell  divisioïi.  Notches,  indenlations  and  irregnlarities  in 
shape  occnr  very  often  in  the  nuclei  of  the  nerve  cells.  If,  however, 
snch  appearances  be  examined  more  closely,  we  shall  find  in  most 
cases  that  they  cannot  be  connted  as  fignres  of  amitotic  divisions. 
Thns  fignres  which  may  with  a great  degree  of  probability  be 
considered  as  stages  of  amitotic  cell  divisions  do  not  occnr  in  snch 
abundance  in  my  préparations  of  the  spinal  cord  from  the  above- 
mentioned  animals.  Fig.  13  shows  a type  of  these  notches,  which 
are  very  common  in  the  nuclei  of  ganglion-cells,  bnt  which,  as  far 
as  one  can  see,  have  nothing  at  all  to  do  with  amitotic  divisions 
of  the  cells.  Figs.  14  and  15  are  cell-plasmodia  or  syncytia,  of  which 
one  often  sees  examples,  es[)ecially  close  to  the  ependyma.  The 
