Am.  Jour.  Pharm.  j 
March,  1918.  > 
Wafer  Ash  Bark. 
2.  A  cork  cambium  (phellogen)  of  delicate-walled  cells,  rich  in 
protoplasm  and  exhibiting  cross  walls.  Many  of  the  cells  of  this 
region  possess  solitary  rhombohedral  crystals  of  calcium  oxalate. 
3.  Several  layers  of  stone  cells  forming  a  continuous  scleren- 
chyme  sheath. 
4.  A  broad  cortex  zone  consisting  of  tangentially  elongated 
cortical  parenchyme  cells  and  intercellular-air-spaces.  Some  of  the 
cortical  parenchyme  cells  contain  numerous  spheroidal  or  ovate 
starch  grains  while  others  contain  rosette  aggregates  of  calcium 
Fig.  2.  Transverse  section  01  wafer  ash  bark,  ss,  secretion  sac;  mr, 
medullary  ray;  S,  region  of  stone  cells  and  rhombohedral  crystals  shown 
enlarged  in  Fig.  3.    (Microphotograph  X22.) 
oxalate.  The  starch  grains  are  simple  or  2  to  4  compound.  Scattered 
about  in  the  cortical  and  outer  phloem  regions  will  be  seen  scleren- 
chyme  elements  either  isolated  or  in  small  groups. 
5.  A  broad  phloem  consisting  of  numerous  phloem  patches 
separated  from  each  other  by  wavy  medullary  rays  which  are  1  to  5 
cells  wide  as  seen  in  tangential  section.  Secretion  sacs  containing 
oil  are  found  scattered  in  both  cortex  and  phloem.  Some  of  the 
intercellular-air-spaces  show  rows  of  calcium  oxalate  crystals. 
Histology  of  Euonymus. — Under  the  microscope,  passing  from 
outer  to  inner  surface,  this  bark  presents  the  following  peculiarities : 
