1040 
Tliat  such  degeneration  is  rather  common  is  also  proved  by  the 
fact  tliat  no  slight  tuimber  of  cells  in  a spinal  ganglion  of  even  a 
young  animal  show  signs  of  degeneration.  The  new  growth  in  this 
region  has  thus  the  task  not  only  of  replacing  the  ganglion-cells 
that  have  been  destroyed  by  degeneration,  but  also  of  inereasing 
their  nuinber.  A fairly  eonsiderable  increase  of  this  kind  takes  places, 
as  is  shown  above,  during  the  anitnal’s  period  of  growth.  To  judge 
from  my  preparations,  nature  seems  in  this  generation  to  make  use 
of  both  mitotic  and  amitotic  division.  In  no  case  have  I been  able 
to  refer  the  cells  that  show  the  latter  type  of  division  to  such  small 
forms  as  those  in  which  mitoses  occur;  the  former  cells  seern  to 
belong  to  remaining  ganglion  cells  that  are  somewhat  older  and 
sometimes,  at  least,  with  a certain  degree  of  development,  for  I 
have  been  unable  to  find  fully  developed  processes  among  them. 
Amitoses. 
Besides  the  figures  of  naitoses  one  also  sees  in  the  preparations 
in  question  figures  of  cells  which  produce  a strong  iinpression  of 
being  engaged  in  direct  division.  As  shown  below  one  sees  cells 
that  seem  to  be  in  different  stages  of  this  division.  The  cells  of  this 
type,  however,  always  belong  to  the  young  ones,  to  those  cells  (in 
the  silver-impregnated  preparations)  that  have  taken  a very  slight 
arnount  of  silver  or  even  none  at  all  during  the  iinpregnation. 
The  different  stages  of  a direct  division  which  are  found  in  ray  pre- 
parations appear  as  follows:  One  sees  cells,  in  which  the  nucleolus 
is  being  divided  or  has  just  divided  (fig.  Ia  and  fig.  26)  and  where 
the  two  nucleoli  are  still  in  each  other’s  immediate  neighbourhood. 
The  two  nucleoli  then  move  away  from  each  other  and  the  nucleus 
begins  to  show  signs  of  incision  in  the  middle  (see  fig.  36  and  fig  26). 
After  this  there  follows  a complete  division  of  the  nucleus,  which 
is  also  frequently  accompanied  by  a division  of  the  protoplasmic 
body,  fig.  3a  and  fig.  2a.  Fig.  3a  must  be  interpreted  as  a young  apolar 
ganglion  cell  in  which,  after  the  nucleus  had  fitst  divided  into  two,  the 
protoplasmic  body  began  to  divide  in  the  middle,  after  which  the  two 
nuclei  again  began  a new  division.  The  preparations  in  which  these 
observations  were  made  were  particularly  well  fixed  and  impreg- 
nated,  so  that  it  is  fairly  certain  that  there  was  no  possibility  of  artificial 
products.  Another  thing  that  further  supports  the  idea  of  natural 
formations  is  the  fact  that  these  figures  above-mentioned  do  not 
occur  in  such  very  great  numbers.  It  is  true  that  there  are  many 
nuclei  of  ganglion  cells  (among  the  smaller  ones)  which  have  two 
