Am.  Jour.  Pharm.  \ 
August,  1898.  J 
Structure  of  Gelsemium, 
381 
OVERGROUND  STEM. 
The  overground  stem  is  that  of  a  woody  climber  (Fig.  /).  It  is 
slender,  on  an  average  about  y2  inch  in  diameter.  Externally  it  is 
nearly  smooth,  marked  by  longitudinal  wrinkles ;  internally  (Fig.  2) 
it  is  whitish,  marked  with  a  pinhole  cavity  in  the  center.  The  epi- 
dermis is,  in  older  plants,  replaced  by  a  thin  layer  of  cork,  from  four 
to  six  cells  thick.  Beneath  this  there  are  a  number  of  rows  of  col- 
lenchyma  cells  containing  chlorophyll.  In  the  parenchyma  cells,  lying 
beneath  the  latter,  are  found  numerous  starch  grains,  oil  globules  and 
large  tetragonal  or  coffin-shaped  crystals  of  calcium  oxalate.  The 
latter  are  found  principally  in  the  cells  at  the  terminus  of  the 
Fig.  3. — Diagram  of  rhizome  of  Gelsemium  sempervirens  (L.),  Pers.  C, 
cork  ;  B,  bast  fibres  ;  3f,  medullar}-  rays,  at  the  periphery  of  which  are  crystals 
of  calcium  oxalate  ;  Ca,  cambium  ;  S,  internal  phloem. 
medullary  ray  cells  of  the  inner  bark.  The  bast  fibers  are  very 
long  and  silky,  and  arranged  in  an  interrupted  circle  through  the 
bark.  Medullary  rays  are  strongly  lignified,  provided  with  simple 
pores,  are  very  regularly  arranged,  widening  from  within  out,  being 
about  eight  cells  in  width  at  the  periphery.  In  the  younger 
plants  the  internal  phloem  is  not  divided,  while  in  the  older  ones  it 
is  divided  into  four  parts,  being  situated  central. 
RHIZOME. 
The  rhizome  creeps  very  near  to  the  surface  (Fig.  1).  It  is  exter- 
nally of  a  brownish-yellow,  and  internally  (F?g.  3)  of  a  yellow  color. 
The  cork  is  about  eighteen  to  twenty  cells  thick.    Underneath  this 
