Am.  Jour.  Pharm.  "I 
March,  1897.  J 
Frangula  and  Cascara  Barks. 
127 
The  description  of  the  gross  characteristics  of  these  barks  may 
contribute  little  to  the  purpose  of  the  investigation;  but  these  should 
be  stated,  as  they  have  a  bearing  upon  pharmacopceial  description, 
an  item  of  interest  to  every  worker  in  pharmacopoeial  revision. 
Taking  the  specimens,  furnished  as  above  stated,  I  should  say 
that  the  pharmacopoeial  description  of  Rhamnus  Purshiana  is  some- 
what faulty ;  the  color  of  the  bark  on  the  outside  cannot  be  con- 
sidered as  a  "  brownish  gray,"  but  a  dark  gray ;  the  thickness, 
instead  of  being  "  about  2  millimeters,"  is  about  I  millimeter.  For 
Fig.  i,  Rhamnus  Purshiana,  cross  section.  A,  epidermis  ;  b,  collenchyma  ; 
c,  sclerenchyma  ;  d,  stone  cells  ;  e,  medullary  ray  ;  fy  bast  bundle  ;  g,  paren- 
chyma ;  h,  crystals  of  calcium  oxalate. 
a  description  of  the  external  characteristics  of  the  three  barks, 
using  the  specimens  furnished  as  a  guide,  I  should  perhaps  adopt 
in  substance  the  following  : 
Rhamnus  Purshiana., — In  quills  or  curved  pieces,  about  3  to  10 
centimeters  long,  and  about  1  millimeter  thick ;  outer  surface  dark 
gray  and  much  encrusted  by  ashen  gray  lichen  patches,  with  longi- 
tudinal grooves  from  3  to  10  millimeters  apart ;  inner  surface 
yellowish  to  light  brownish,  becoming  darker  by  age;  smooth, 
glossy  and  finely  striate ;  fracture  short,  yellowish  ;  in  the  inside 
