Am.  Jour.  Pharm. 
June,  1897. 
Alexandria  and  India  Senna. 
299 
scope  whose  optical  parts  were  a  Zeiss  8  mm.  apochromatic  objec- 
tive and  a  No.  2  projection  eye-piece.  The  source  of  illumination 
was  the  arc  light,  the  crater  of  which  was  carefully  focussed  upon 
the  object  by  the  condenser.  The  actual  magnification,  measured 
by  projecting  the  image  of  a  stage  micrometer  upon  the  ground 
glass  of  the  camera,  is  240  diameters.  No  retouching  or  other 
alterations  of  the  negative  have  been  made.    The  drawings  of  parts 
Fig.  1.  India  senna,  under  side  of  leaf ;  a,  epidermal  cell 
hair  ;  d,  hair  scar  ;  e,  nebenzellen. 
b.  stomata  ;  c. 
found  in  the  powder  were  all  made  by  the  camera  lucida  under  like 
conditions  of  preparation  and  magnification.  The  amplification 
here  is  200  diameters. 
At  the  commencement  of  the  work,  in  order  to  find  some  point 
of  characteristic  importance,  the  parts  were  thoroughly  studied  in 
their  natural  relations  by  means  of  sections,  and  the  appearances 
there  observed  were  then  made  the  object  of  study  in  the  powder. 
