.Am.  Jour.  Pliai  m.  \ 
July,  1881.  J 
False  and  True  Senega. 
323 
compact,  with  slightly  curved  numerous  medullary  rays,  composed  of 
small  flat  parenchyma  cells ;  the  woody  cells  are  small,  somewhat  oval 
shaped,  intermixed  with  larger  ducts,  of  the  same  shape,  arranged  in 
three  distinct  circles. 
In  longitudinal  section,  the  corky  layer  of  the  bark  is  rather  irreg- 
ular; in  the  next  layer  the  cells  are  long  and  flattened,  followed  by  some- 
what larger  oval  cells,  and  then  by  long,  flattened,  very  compact  liber 
cells,  and  Anally  by  shred-like,  very  compact  cells,  and  by  the  thin 
cambium.  The  wood  is  composed  of  prosenchyma  tissue,  with  large 
ducts. 
The  true  senega,  when  transversely  cut,  exhibits  a  bark  with  a  very 
thin  corky  layer,  and  consists  of  hexagonal  cells,  forming  three  layers, 
the  cells  of  the  inner  layer  being  much  smaller  in  size.  Inside  of  the 
thin  cambium  layer  is  the  radiating  woody  portion,  composed  of  wood 
cells  and  hexagonal  ducts,  arranged  in  straight  lines,  occasionally  in 
pairs,  and  about  four  times  as  large  as  the  adjoining  cells. 
Senega  Root. — Transverse  and  longitudinal  section  to  center. 
In  the  longitudinal  section  are  seen  the  thin  corky  layer,  the  some- 
what loose-celled  middle  bark,  the  dense  inner  bark  containing  elon- 
gated cells,  the  thin  cambium,  and  the  compact  wood  with  large 
ducts. 
Polygalic  acid,  being  the  active  constituent  in  senega,  the  writer's 
experiments  have  been  chiefly  directed  to  the  elimination  of  that  prin- 
ciple in  the  two  drugs. 
Ten  troy  ounces  of  the  false  senega  were  treated  as  directed  by  Proc- 
ter, in  the  American  Journal  of  Pharmacy,"  1860,  page  150.  The 
powder  was  exhausted  by  percolation  with  a  mixture  of  two  parts  of 
alcohol  and  one  of  water  until  the  percolate  was  free  from  taste  and 
•ceased  to  give  a  precipitate  with  basic  acetate  of  lead.    Tliis  percolate 
