424  Gelsemium  Sempervirens,  Ait.  {^ptembefS?' 
four  times  its  size.  He  notes  the  presence  of  the  four  medullary 
phloem  patches,  and  their  encroachment  upon  the  pith  area. 
A  great  deal  of  work  has  been  done  upon  .Gelsemium  from  a 
chemical  and  pharmaceutical  standpoint,  but  its  structure  and  de- 
velopment have  not  been  thoroughly  worked  out.  The  root  con- 
tains an  alkaloid  gelsemin,  which  is  very  poisonous,  but  is  a  valua- 
ble medicine  when  taken  in  proper  quantities.  The  medicinal 
properties  of  Gelsemium  were  accidentally  discovered  about  the 
middle  of  this  century.  An  interesting  account  of  the  discovery 
and  the  primitive  method  of  extracting  the  poisonous  principle  from 
the  root  is  given  by  William  Procter,  Jr.,  in  the  American  Journal 
of  Pharmacy  for  1852. 
Other  records  of  the  investigations  upon  the  alkaloid  gelsemin 
are  to  be  found  in  later  numbers  of  this  Journal,  and  in  the  <•  Pro- 
ceedings of  the  American  Pharmaceutical  Association." 
HISTOLOGY  OF  A  ONE-YEAR-OLD  STEM. 
A  transverse  section,  about  I  millimetre  in  diameter,  of  an  inter- 
node  at  the  close  of  the  first  year's  growth  shows  the  following 
structure  [Fig.  1).  Externally  are  three  to  four  layers  of  cork, 
still  covered  in  places  by  the  prominently  ridged  cuticle ;  nex^ 
is  the  cortex,  consisting  of  a  zone  of  parenchyma  four  to  five  cells 
deep,  rich  in  protoplasm  and  containing  abundant  chlorophyl  and 
starch  grains.  A  ring  of  large  sclerotic  cells,  which  appear  in  lon- 
gitudinal section  as  clear  refractive  fibres  of  considerable  length, 
lies  on  the  outer  margin  of  the  vascular  bundle  portion  of  the  stem. 
The  bundle  cylinder  consists  first  of  a  zone  ot  external  phloem 
about  six  cells  deep.  Most  of  the  cells  are  still  embryonic,  with 
large  nuclei  and  abundant  protoplasm,  some  few  have  differentiated 
into  sieve  tubes.  In  longitudinal  section  the  sieve  plates  can  be 
recognized.  The  septa  are  large,  transversely  placed,  and  bear 
either  four  or  three  sieve  plates  with  numerous  perforations.  The 
cambium  layer  is  clearly  defined  by  its  regular  brick-shaped  cells 
with  large  nuclei. 
The  wood  is  a  broad  zone,  occupying  more  than  ,a  third  of  the 
area  of  the  section,  and  is  traversed  radially  by  the  oblong,  deeply 
pitted  cells  of  the  medullary  rays.  A  longitudinal  section  througli 
the  wood  shows  numerous  spiral  tracheae  in  the  inner  or  protoxy- 
lem  region;  external  to  this  are  both  short  and  long  tracheids, 
