128 
Frangula  and  Cascara  Barks. 
Am.  Jour.  Pharm. 
March,  1897. 
layer  of  thick  bark,  somewhat  fibrous  and  slightly  bitter.  When 
chewed  the  bark  imparts  a  yellowish  color  to  the  saliva. 
Rhamnus  California. — In  quills  or  curved  pieces  about  3  to  10 
centimeters  long,  and  about  1*5  millimeters  thick;  outer  surface 
grayish  brown,  beset  with  numerous  lenticels,  which  are  Irom  round 
to  transversely  elongated,  infrequently  longitudinally  elongated,  and 
often  longitudinally  confluent.  On  scraping  the  surface  of  the  bark 
a  reddish  brown  color  is  observed,  which  is  due  to  the  contents  of 
Fig.  2,  Rhamnus  Purshiana,  longitudinal  section.  A,  epidermis  ;  b,  collen- 
chyma  ;  c,  sclerenchyma  ;  d,  stone  cells  ;  e,  medullary  ray  ;  f,  bast  bundle  ;  gy 
parenchyma  ;  k,  crystals  of  caleium  oxalate.' 
the  cork  cells.  Inner  surface  reddish  brown  to  dark  brown  ;  smooth, 
glossy  and  finely  striate ;  fracture  short  (inner  layer  of  thick  bark, 
although  somewhat  fibrous ;  breaks  with  a  short  fracture);  inodorous 
and  slightly  bitter.  When  chewed  the  bark  imparts  an  orange-red- 
ish  color  to  the  saliva. 
Frangula. — See  U.S.P.  External  character  of  this  bark  answers 
well  to  official  description. 
From  the  marked  physical  distinction  between  these  barks,  one 
