Since  bud-variations  are  of  very  rare  occurrence,  and  only
one  of  many  thousand  buds  on  the  same  plant  varies  so  as  to
produce  red  leaves,  for  instance,  while  the  altered  conditions
simultaneouslv  affect  all  the  buds,  I  conclude  that  the  modified
determinants  which  the  tree  contains  may  sometimes  attain  a
majority  in  consequence  of  an  abnormal  differential  nuclear
division.  Should  this  take  place  in  the  apical  cell  or  cells
of  a  bud,  the  resulting  shoot  might,  to  return  to  our  former
example,  bear  both  green  and  red  leaves ;  for,  according  to  our
pre-supposition,  the  *  green '  and  *  red '  determinants  of  the
apical  cells  would  have  been  separated  during  the  cell-divisions
in  such  a  manner  that  in  some  leaves  the  green  determi-
nants, and  in  others  the  red  ones,  might  be  in  the  majority.
If  the  separation  occurs  at  an  earlier  stage,  before  the  apical
cells  are  formed,  —  that  is  to  say,  in  the  cambium,  —  a  shoot
bearing  red  leaves  alone  might  arise  from  the  cell  which
receives  the  *  red '  group  at  the  differential  division  of  the
nucleus.
There  is  nothing  impossible  about  this  assumption ;  for  during
the  process  of  mitotic  nuclear  division,  irregularities  might  occur
in  the  complex  apparatus  by  which  this  process  is  effected,
and  individual  cases  of  such  irregularity  have  actually  been
observed :  —  even  the  possibility  of  a  direct  nuclear  division
cannot  be  entirely  overlooked.  I  am,  however,  far  from  con-
sidering this  hypothesis  as  established,  and  merely  offer  it  as  a
suggestion.
