Am.  Jour.  Pharm. ) 
September,  1914.  j 
Rhamnus  Purshiana. 
397 
which  are  peculiar  to  this  bark,  and  with  small  groups  of  brownish 
apothecia,  longitudinally  striate,  turning  red  when  moistened  with 
solutions  of  the  alkalies;  fracture  short,  with  projections  of  bast 
fibres  in  the  inner  bark,  the  medullary  rays  one  or  two  cells  wide, 
forming  converging  groups ;  in  cross  section  this  inner  surface  of 
the  bark  indistinctly  crenate ;  odor  distinct ;  taste  bitter,  slightly  acrid. 
(Dr.  Henry  Kraemer,  "  Botany  and  Pharmacognosy,"  3rd  Edition, 
P-  524.) 
Fig.  4. — Packing  Cascara  bark  to  trail.    Because  of  the  underbrush  and  fallen  timber  horses 
cannot  be  used  except  on  trails. 
Description  of  the  Powdered  Bark. — The  powdered  bark  is 
light  brown ;  bast  fibres  long,  much  thickened,  lignified ;  stone  cells 
very  thick-walled,  about  50  fi  in  diameter,  crystal  fibres  containing 
monoclinic  Crystals  of  calcium  oxalate;  calcium  oxalate  also,  in 
rosette  aggregates  or  monoclinic  prisms  5  to  20  fx  in  diameter ;  starch 
grains  spherical,  about  4  ^  in  diameter;  parenchymatous  cells  with 
yellowish  contents  colored  red  with  alkalies.  (Dr.  Henry  Kraemer, 
"  Botany  and  Pharmacognosy,"  3rd  Edition,  p.  759.) 
Structure  of  the  Bark.— The  bark  as  described  by  Prescott 
consists  of  three  parts ;  namely,  the  corky  layer,  the  middle  bark,  and 
the  inner  bark. 
