Am.  Jour.  Pharm.  \ 
May,  1881.  J 
jRkus  Aromatica. 
211 
the  cork  consists  of  three  rows  of  flattened  tangentially  elongated 
parenchyma  cells,  followed  by  one  of  loose  parenchyma  and  sieve 
lubes.    The  next  layer  consists  of  three  rows  of  bast  cells,  interrupted 
Bark  of  the  root  Rhus  Aromatica,  Aiton. 
1.  Transverse  section.  2,  Longitudinal  section, 
3.  Crystals  of  pliosx)hates.  4.  Crystals  of  chlorides. 
5.  Crystals  of  calcium  oxalate. 
by  oil  tubes.  The  succeeding  layers  are  composed  of  ordinary  paren- 
chyma, sieve  tubes  and  bast  cells,  some  of  the  rows  of  the  latter  being 
interrupted  by  oiljtubes  the  same  as  those  just  described.  The  medul- 
