AmM5ch,f895rm'}    The  Apocynacecz  in  Materia  Medica.  159 
BARKS. 
Nerium  Oleander. — The  bark  of  Nerium  Oleander  L.  is  the  only 
one  of  note  of  this  family  obtained  from  Europe.  The  stem  is 
vaguely  triangular  or  tetragonal,  depending  whether  the  leaves  are 
ternate  or  opposite.  The  bark  is  externally  yellowish  green  in  the 
young  parts,  soon  becoming  grayish.  The  internal  face  is  greenish 
white,  the  fracture  green,  the  latex  originates  especially  in  the 
internal  region  of  the  bark,  which  is  quite  thick  compared  with  the 
wood.  The  liquid  is  likewise  abundant  in  the  neighborhood  of  the 
periphery  of  the  pith,  which  is  large,  triangular  or  square,  greenish 
yellow,  with  a  green  line  of  contact  with  the  wood.  The  leaves  and 
young  stems  appear  absolutely  glabrous.  The  microscope,  how- 
ever, shows  a  few  hairs,  very  short  and  large,  unicellular,  with  a 
small  cavity. 
Anatomy.— The  young  bark  of  the  stem  shows :  an  epidermis 
with  walls  externally  thickened,  soon  replaced  by  a  zone  of  a  few 
suberous  layers  ;  a  collenchyma  very  clear  and  quite  thick,  with 
elements  elongated  in  the  direction  of  the  axis ;  these  contain 
chlorophyll  and  starch ;  a  chlorophyll-bearing  tissue  with  rounded 
thin-walled  cells  containing  an  abundance  of  starch.  The  Endodermis 
is  not  visible  excepting  near  the  summit  of  the  stem.  The  pericycle 
is  thick  and  contains  the  bundles  of  cellular  fibres  extremely  long, 
pearly  white,  and  with  cavities  very  straight,  often  flattened ;  and 
the  cells  with  a  thin  membrane  with  macles  of  calcium  oxalate.  The 
liber  encloses  not  macles,  but  numerous  rhomboids,  often  in  longi- 
tudinal or  radial  series.  Sometimes  a  number  of  crystals  are 
enclosed  in  a  single  cell.  Cambium.  Wood  rich  in  starch.  The 
laticiferous  vessels  are  difficult  to  see ;  we  find  them  especially  in  the 
pericycle  and  in  the  exterior  parenchyma. 
The  Bark  of  Thevetia  Neriifolia  Juss.  Generally  the  bark  is 
obtained  from  the  young  branches ;  it  is  thin,  delicate,  strongly 
enrolled  upon  itself  from  one  or  both  borders.  The  surface  is  gray, 
greenish  or  a  little  yellow,  rarely  glossy,  is  finely  striated  longitudi- 
nally, with  few  whitish  streaks,  more  or  less  numerous  elongated 
lenticels  and  scars  of  the  alternate  leaves.  The  internal  face  is 
bluish-black  or  reddish-violet,  smooth.  The  fracture  sometimes 
quite  clear,  is  nearly  always  lengthily  fibrous,  with  soft  fibres  in  the 
liber.  The  length  is  variable,  15  to  20  cm.;  the  thickness  1  m.m. 
or  more  ;  odorless  ;  taste  pungent,  then  strongly  bitter. 
