THE 
AMERICAN  JOURNAL  OF  PHARMACY. 
MAY,  1866. 
AN  ESSAY  ON  SENNA  AND  ITS  ACTIVE  PRINCIPLE. 
By  Robert  Rau,  Bethlehem,  Pa. 
(An  Inaugural  Essay  presented  to  the  Phila.  Coll.  Pharm.,  1866.) 
There  is  perhaps  no  drug  in  our  list  of  Materia  Medica,  in 
the  chemical  analysis  of  which  so  much  difficulty  seems  to  have 
been  found,  and  concerning  the  results  of  which  analyses  so 
much  variance  and  discrepancy  exist.  The  active  or  purgative 
principle  has  for  a  long  time  been  ^'supposed  to  be  represented  by 
an  amorphous,  extractive-like  substance,  which  has  been  termed 
"  Cathartin."  Within  a  few  years  this  idea  has  been  abandoned, 
and  certain  chemists  have  pronounced  as  their  conviction,  that 
the  principle  in  question  is  analogous  to  that  existing  in  the 
officinal  species  of  Rheum,  and  found  in  Rumex  Crispus,  and  in 
several  genera  of  the  order  "  Polygonaceae." 
The  writer  of  this  has  found  recorded  no  process  nor  conclu- 
sive arguments  on  which  this  announcement  is  founded ;  more- 
over the  existence  of  the  same  purgative  principle  in  two  drugs 
so  widely  different  in  their  botanical  relations,  and  differing  even 
in  their  more  particular  medicinal  effects,  cannot  but  seem  very 
remarkable  and,  indeed,  not  very  plausible.  It  is  true,  we  have 
examples  in  the  history  of  medicinal  organic  products  in  which 
the  same  principle  exists  in  plants  seemingly  different  in  outward 
characters,  and  separated  in  botanical  classifications. 
Thus  we  find  the  alkaloid  "Berberina"  in  the  genera  Podo- 
phyllum, Berberis,  Cocculus,  Hydrastis,  Coptis  and  Xanthor- 
rhiza ;  these  representing  the  natural  orders  Banunculacese,  Ber- 
