164 
Wafer  Ash  Bark. 
(Am.  Jour.  Pharm. 
March,  1918. 
1.  An  irregular  cork  zone  showing  lenticels  and  many  layers  of 
tangentially  elongated  cork  cells  whose  walls  may  be  either  suber- 
ized  or  slightly  lignified. 
2.  A  cork  cambium  of  meristematic  cells. 
3.  A  narrow  cortex  of  cortical  parenchyme  cells,  some  of  which 
contain  more  or  less  spheroidal  starch  grains  while  others  contain 
rosette  aggregates  of  calcium  oxalate. 
Fig.  3.  Transverse  section  through  outer  portion  of  wafer  ash  bark 
(highly  magnified).  A,  cork;  B,  cork  cambium;  C,  solitary  rhombohedral 
crystal  of  calcium  oxalate ;  D,  stone  cells ;  E,  cortical  parenchyma  containing 
small  starch  grains  and  rosette  aggregates  of  calcium  oxalate.  (Photomi- 
crograph X  200.) 
4.  A  very  broad  phloem,  occupying  most  of  the  width  of  the  sec- 
tion and  consisting  of  cone-shaped  phloem  masses  (in  cross  section) 
traversed  by  wavy  secondary  medullar  rays.  Primary  medullary 
rays  separate  the  cone-shaped  phloem  masses  one  from  the  other. 
These  are  one-cell  wide  in  the  inner  phloem  but  broaden  out  into 
fan-shaped  wedges  farther  out.  Some  of  the  phloem  cells  and 
medullary-ray  cells  contain  starch  grains  while  others  possess  rosette 
aggregates  of  calcium  oxalate.  Secretory  cells  containing  a  caout- 
chouc-like substance  which  dissolves  in  chloroform  and  carbon  di- 
sulphide  are  found  scattered  about  amidst  other  cells  of  the  phloem 
region. 
