1052 
add  that  tliis  picture  is  tlje  onlj  oiie  among  uiy  exteiisive  material 
iii  which  1 found  such  far  advanced  incisions  in  the  nuclei,  these 
facts  certainly  support  tlie  idea  that  there  reallj'  are  natural  forma- 
tions.  AH  these  cells  that  show  signs  of  amitotic  division  are  very 
young.  Some  of  thein  have  no  signs  at  all  of  processes  (fig.  19  and 
20),  while  others  show  indications  of  the  beginning  of  a develop- 
inent  of  these  (figs.  9b,  16,  17,  18,  and  21).  I can  agree  with  Pala- 
DiNo’s  statement  quoled  above  that  it  is  onlj  before  the  ditferentia-  ; 
tion  of  the  processes  that  amitotic  division  takes  place.  On  the  strength 
of  the  appearances  in  this  material  I am  of  the  opinion  that  the 
amitotic  division  proceeds  in  the  way  ; 
a)  The  nucleolus ‘)  increases  in  length  and  begins  to  show  incisions 
in  the  middle  ; this  incision  becomes  deeper  and  deeper  (figs  16  and 
17)  and  finally  one  has  a division  into  two  nucleoli,  each  of  which  i 
moves  to  an  end  of  the  nucleus  of  the  cell,  which  has  begun  to  i 
become  drawn  out  into  a more  or  less  oval  formatiou.  The  nucleoli  > 
often  exhibit  a continued  power  of  generation  even  after  they  have 
moved  out  to  the  future  daughter-nuclei ; it  is  this  that  causes  us  ' 
often  to  see  in  such  daughter-nuclei  either  one  nucleolus  engaged 
in  direct  division  or  else  several  nuclei,  a number  of  which  maj 
be  seen  moving  out  of  the  nucleus.  I have  not  been  able  to  decide  i 
with  certainty  whether  the  lilameuts  (nuclear  übres)  of  the  nucleus  i 
thereby  have  any  specitic  function.  It  is  a fact,  however,  that  there  ^ 
are  sometimes  appearances  which  point  to  this  being  really  the  case  j 
(tig.  16  and  17).  b)  The  drawn-out,  elliptical  nucleus  begins  to  show  | 
signs  of  incision  in  the  middle  (fig.  16,  17,  and  18).  This  incision 
usually  takes  place  iu  the  middle,  so  that  the  two  daughter-nuclei 
are  equally  large.  There  are,  however'  figures  showing  the  existence 
of  a slight  dissymmetry  (tig.  18).  The  incision  grows  deeper,  but  is 
not  as  a rule,  however,  deeper  than  is  shown  in  tig.  20,  the  con- 
nection  between  the  nuclei  being  retained.  Incision  of  the  nuclei  as 
far  advanced  as  that  sliown  in  figs.  9b  and  21  is  exceedingly  infre- 
quent  and  these  figures  are  the  oidy  ones  I found  of  this  type. 
There  are  also  figures  that  indicate  that  the  fibres  of  the  nucleus  i 
may  have  something  to  do  with  the  division  óf  the  nucleus,  c)  If 
the  cell  in  which  the  nucleus  divides  amitotically  is  at  a very  early 
stage  of  development,  a cleavage  of  the  protoplasm  does  not,  in 
most  cases,  ensue,  but  a cell  plasmodium  arises.  These  cells  are  i 
h It  should,  however,  be  noted  that  such  phenomena  of  new  growth  often  appear 
in  the  nucleoli  without  the  nucleus  otherwise  showing  any  signs  of  an  amitotic 
division. 
