Anatomie  — De  Heer  Boeke  biedt  eene  niededeeling  aan  van  den 
Heer  Erik  Agduhr:  the  post-einhryonic  groivth  of  the 
nervous  system  due  only  to  an  increase  in  size  or  also  to  an 
increase  in  nuinber  of  the  nenrones?”  (Second  part). 
(Mede  aangeboden  door  den  Heer  Winkler). 
Mitoses. 
In  connection  with  tliese  matters  I have  found  speeialljMnteresting 
phenoniena  in  the  thoracic  region  of  a puppy  seventee)i  days  old.  The 
spinal  gaiiglia  were  tixed  according  to  Flemming’s  method,  cut  up  in 
paraffin  sections  from  3 p to  5 p tljiek  and  stained  witli  the  iron 
aluin  hematoxilin  of  Heidenhain.  In  these  continuous  series  of  sections 
I found  a large  nuniber  of  mitoses  — an  approximate  calculation 
showed  that  in  a single  one  of  these  ganglia  there  were  over  two 
hundred  mitoses.  Eigures  5,  6,  7,  and  8 show  how  these  mitoses  appear 
in  the  preparation.  One  would  be  inclined  at  first  sight  to  refer  these 
mitoses,  especially  the  ones  reproduced  in  figures  5 and  6,  to  the 
large  ganglion  cells  — the  light  tield  round  the  chromatin  showing, 
of  course,  a rather  diffuse  transition  to  the  rest  of  the  protoplasm. 
Owing  to  the  continuous  series  I was  able,  however,  to  follow  the  ! 
cells  from  one  section  to  the  other,  and  then  I found  that  the  real 
nuclei  of  these  ganglion  cells  were  not  found  in  a stage  of  division, 
and  that  these  mitoses  must  belong  either  to  other  small  cells  situated  , t 
between  the  ganglion  cell  and  its  capsule  or  probably  to  cells  that  1 
form  the  capsule  itself.  In  fig.  7,  on  the  other  hand,  merely  from  ■ 
the  Sharp  outline  which  the  light  field  makes  against  fhe  surrounding  3 
protoplasm  it  is  clear  that  there  can  be  scarcely  any  question  of  fll 
the  existence  of  a mitosis  in  the  ganglion  cell  — this  was  also  «} 
confirmed  by  the  inyestigation  of  the  same  ganglion  cell  in  the  A 
preceding  and  following  sections.  In  fig.  8 we  have  again  an  example 
of  a cell  which  is  going  to  divide  mitotically,  and  which  is  situated  | 
outside  the  capsules  of  the  surrounding  ganglion  cells.  With  regard  \ 
to  size  it  resembles  most  closely  the  cells  in  mitotical  division  in  i 
figures  6,  7,  and  8,  but  on  closer  examination,  for  instance,  if  they  . j 
are  traced  from  section  to  section,  one  finds  that  it  is  surrounded  j 
by  capsule  cells.  Wé  fhus  seem  to  be  quite  justified  in  describing  1 
