Am.  Jour.  Pharm.  \ 
March,  1897.  J 
Frangula,  and  Cascara  Barks. 
129 
might  suppose  it  an  easy  task  to  distinguish  between  them  in  pow- 
der; but  such  is  not  the  case;  although  differing  widely  in  ap- 
pearance, they  possess  very  similar  microscopical  or  anatomical 
structure.  The  points  of  similarity  may  be  stated  briefly  as  fol- 
lows : 
(1)  Narrow  medullary  rays,  which  extend  nearly  to  thefcork, 
these  rays  in  Rhamnus  Purshiana  converging  at  their  outer  ends. 
Fig.  j,  Rhamnus  Frangula,  cross  section.  A,  epidermis  ;  b,  collenchyma  ;  c, 
sclerenchyma  ;  e,  medullary  ray  ;  f}  bast  bundle  ;  g,  parenchyma  ;  k,  crystals 
of  calcium  oxalate. 
(2)  Numerous  small  groups  of  bast  scattered  somewhat  regularly 
throughout  nearly  the  whole  bark,  the  number  of  fibres  in  the  bast 
bundle  varying  from  2  to  3  to  perhaps  25  in  each  bundle. 
(3)  Each  bundle  of  bast  is  bordered  by  a  layer  of  thin-walled 
cells,  filled  with  cubical  crystals  of  calcium  oxalate;  these  crystal 
cells  appearing  very  distinctly  in  longitudinal  section,  and  in  the 
powder.    (See  drawings.) 
1 
