Am.  Jour.  Pharm. 
September,  189!). 
Gelsemium  Semper vir ens,  Ait. 
.431 
scribed  above  for  adult  leaves.  Scott,  in  his  work  upon  Ipomcea 
versicolor,  found  that  in  the  hypocotyl  near  its  junction  with  the 
root,  the  internal  phloem  passed  through  the  xylem  and  joined  the 
external  phloem.  He  was  thus  able  to  prove  the  continuity  of  the 
phloem  throughout  the  plant.  Similar  phenomena  were  observed 
by  Gerard  in  different  plants.  There  is  no  trace  of  any  continuity 
between  the  external  and  internal  phloem  of  the  hypocotyl  of  Gel- 
semium. The  course  of  the  bundles  throughout  the  hypocotyl  and 
stem  is  indicated  in  the  diagrammatic  figure  below  {Fig.  5). 
0,  origin  of  first  pair  of  internal  phloem  patches  ;  ol,  origin  of  second  pair  ; 
co,  cotyledon;  I1,  first  foliage  leaf;  I'2,  second  foliage  leaf;  I3,  third  foliage 
leaf  ;  ga,  growing  apex  ;  x,  crossing  of  internal  phloem  to  exterior. 
In  the  growing  apex  of  the  stem  the  first  cells  to  differentiate 
from  the  primary  meristem  are  the  spiral  tracheae  of  the  protoxy- 
lem,  which  are  arranged  in  radial  rows.    On  their  outer  border  ap- 
Fig.  5. 
ORIGIN  OF  THE  INTERNAL  OR  MEDULLARY  PHLOEM. 
