626 
M  uira-Puama. 
5  Am.  Jour.  Pharm. 
(     Sept.,  1921. 
HISTOLOGY  OF  ROOT. 
Sections  of  the  root  disclose  the  following  microscopical  char- 
acteristics, passing  from  periphery  toward  the  centre: 
1.  Cork,  composed  of  several  layers  of  tabular  cells  with  brown- 
ish contents  and  more  or  less  lignified  walls. 
2.  Phellogen,  of  clear  meristematic  cells. 
3.  Secondary  Cortex,  composed  of  a  number  of  layers  of  paren- 
chyma, some  of  the  cells  of  which  contain  a  reddish-brown  resin, 
others  starch,  still  others  monoclinic  prisms  of  calcium  oxalate. 
Imbedded  in  this  region  are  scattered  islands  of  sclerenchyma, 
accompanied  by  crystal  fibers,  the  individual  cells  of  which  contain 
rhombohedral  crystals  of  calcium  oxalate. 
4.  Phloem,  a  narrow  zone  of  sieve  tubes  and  phloem  paren- 
chyma. Isolated  groups  of  thick  walled  bast  fibers  accompanied  by 
crystal  fibers  are  found  amongst  the  other  phloem  elements. 
5.  Cambium,  a  prominent  zone  of  meristematic  cells. 
6.  Xylem,  a  very  broad  central  zone  of  radially  arranged  wood 
wedges  separated  by  starch  containing  medullary-rays.  Each  xylem 
wedge  is  composed  of  numerous  wood  fibers  with  thick,  lignified  walls, 
scattered  amongst  which  are  starch  and  crystal  containing  wood 
parenchyma  cells  and  tracheae  with  bordered  pores  and  simple  pits. 
Crystal  fibers  containing  monoclinic  prisms  of  calcium  oxalate  fre- 
quently adhere  to  the  wood  fibers. 
POWDERED  DRUG. 
Light  brown;  the  characteristic  elements  being  the  following: 
Starch  grains  which  are  simple  or  2-4-compound  (usually  2-3- 
compound),  the  individual  grains  spheroidal,  plano-convex,  or  bi- 
truncate  and  up  to  15  microns  in  diameter;  numerous  calcium  oxa- 
late crystals,  both  as  crystal  fibers  and  rhombohedra;  numerous  frag- 
ments of  sclerenchyma  fibers,  the  latter  often  accompanied  by  crystal 
fibers  containing  rhombohedral  crystals  of  calcium  oxalate ;  occa- 
sional stone  cells  with  thick,  lignified,  porous  walls;  numerous  frag- 
ments of  tracheae,  some  of  which  have  bordered  pores,  others  simple 
pits;  resin  cells  with  dense  brownish  contents. 
