Am.  Jour.  Pbarm. 
June,  1897. 
Alexandria  and  India  Senna. 
303 
two  with  two  nebenzellen,  fifteen  with  three,  and  three  with  four. 
These  results  seem  to  eliminate  the  epidermal  cells  from  further 
consideration,  but  more  of  value  may  be  expected  of  the  stomata. 
Exception  will  have  to  be  taken,  however,  to  the  statements  made 
by [ Schneider  concerning  the  number  and  size  of  the  neighbor-cells 
(nebenzellen).     That  the  India  senna  usually  possesses  two,  and 
4 
Fig.  4.  Alexandria  senna,  upper  side  of  leaf ;  a,  epidermal  cells  ;  b,  stomata  ; 
c,  hair  (in  focus)  ;  d,  hair  scar ;  e,  nebenzellen. 
the  Alexandria  senna  a  larger  number,  is  easily  disproved  by  the 
accompanying  figures. 
Likewise  the  statement  that  when  two  are  present  in  the 
Alexandria  senna  they  are  of  equal  size,  cannot  be  confirmed  by 
examination.  (See  Figs.j  and  ^.)  But  whatever  number  may  obtain 
in  either  case,  it  is  so  inconstant  a  character  as  to  be  of  no  value 
as  a  discriminating  factor.  There  is,  on  the  contrary,  a  point  of 
great  distinctive  value  to  be  found  in  the  size  and  shape  of  the 
