1032 
Kaïiiiichen  überzeiigen  konnte,  plij’siologiscliei’ Weise  ziun  Unlergang 
speziell  der  grossen  Spinalganglienzellen.  Die  Degeneration  verlauft 
in  verseliiedenen  Forinen  nnd  allem  Anscliein  nach  wenig  rapid. 
Man  siet  in  einem  Spinalganglion  des  Froselies  c.a.  20 — 25  iinter- 
geiiende  Zeilen,  beim  Kaninchen  relativ  nocb  viel  weniger.  Die  ver- 
loren gegangenen  Zeilen  müssen  ersetzf  werden  nnd  dies  gescbieht 
wabrselieiidieli  dadnrch,  das  eine  der  kleinen  dundi  Wacbstnni  ilire 
Stelle  einniinint.  Da  nacdi  dein  friihesten  Jngendstadinm  eine  Vermehrnng 
von  Nervenzellen  nicdit  niebr  vorkoinint,  innss  das  Spinalganglion, 
nni  tnr  die  Zeit  des  Lebens  fnnktionstaliig  bleiben  zn  können,  in 
der  Alliage  genügendes  Ersaizinaterial  in  Geslalt  von  Reservenzellen 
mitbekominen.  Genanere  üntersneliiingen  hieritber  zn  inachen,  bin 
icli  indessen  noch  nicht  in  der  Lage  gewesen.”  With  regard  to  this 
Hatai  States:  “The  above  inter|>retation  giveii  bj  Bühi.eh  concerning 
the  sniall  cells  cannol  be  accepted  as  far  as  white  rats  are  concerned, 
for  he  regarded  the  small  cells  as  replacing  the  degenerated  large 
nerve  cells;  if  this  were  the  case,  then  the  total  nnniber  of’  the 
spinal  ganglion  cells  innst  be  decreased,  bnt  the  preceding  table 
shows  that  the  total  nnmber  is  approxiinatelj  constant.” 
I have  observed  in  a nnniber  of  cases  in  preparations  fi’om  dogs 
that  a nnmber  of  the  larger  ner\e-cells  in  the  spinal  ganglion  show 
signs  of  being  in  process  of  degeneration,  and  in  raj  opinion  Bühleh 
is  right  in  sayiiig  that  these  degeiiei’ating  cells  are  replaced  by 
yonng  cells  which  grow  out  in  their  place.  Hatai’s  argument  to  the 
contrary  : “If  this  were  the  case,  then  the  total  nnmber  of  the  spinal 
ganglion  cells  mnst  decrease”  proves  nothing  at  all.  It  is  even  fairlj 
certain  that  the  degenerate  cells  are  replaced  bj  jonng  cells,  which 
grow  ont  and,  notwithstanding  this  degeneration,  increase  the  absolute 
nnmber  of  ganglion  cells  dnring  the  post-embrjonal  growth.  As  a 
matter  of  fact,  Hatai  lias  nnconscionsly  proved  this  last  point  by 
bis  calcnlations  (Table  h),  and  bis  evidence  in  favonr  of  it  would 
certainly  have  been  very  mnch  clearer  if  he  had  made  nse  of  greater 
material  and  had  counted  the  cells  in  a larger  nnmber  of  corres- 
ponding  spinal  ganglia  in  the  animal  investigated. 
The  calcnlations  I am  making  (which  1 have,  however,  not  yet 
completed)  of  the  nnmber  of  ganglion  cells  in  the  spinal  ganglia  of 
animals  of  different  ages  in  the  same  litter,  seem  to  show  that  there 
really  is  an  increase  in  the  nnmber  of  ganglion  cells  dnring  post- 
embryonal  life,  althongh  this  increase  is  not  nearly  so  large  as  the 
increase  in  the  axons.  My  preparations  have  also  afforded  Information 
as  to  the  way  in  which  this  increase  is  bronght  abont. 
{To  he  continued). 
