Amju{yUri9^7arm'}    The  Pharmacognosy  of  Helonias.  295 
their  location.  Narrow  bands  of  trachea  extend  from  the  epidermis 
entirely  through  the  cortex,  to  and  even  through  the  pericycle. 
There  is  no  distinct  endodermal  layer  and  the  mestome  strands  are 
of  the  collateral  type. 
Fig.  3,  a  radial-longitudinal  section  through  the  cortex  of  he- 
lonias rhizome,  shows  a  foramen  in  longitudinal  section.    The  walls 
A- 
Fig.  5.  Section  of  Helonias  rhizome,  cut  at  right  angles  to  the  entering 
roots,  or  at  an  angle  of  about  forty-five  degrees.  This  section  shows  five 
roots  entering  the  cortex  through  their  respective  foramina.  It  will  be  noted 
that  the  cortex  of  the  roots  gradually  narrows  as  the  roots  approach  the 
central  cylinder.  It  also  gives  an  excellent  view  of  the  tube  walls,  which  are 
seen  to  be  uniformly  thickened.  A,  tube  wall;  B,  endodermal  layer  of  root; 
C,  pentarch  mestome;  E,  endodermal  layer  of  rhizome. 
of  these  root-carriers  are  made  up  of  longitudinally  elongated  cells 
which  are  regular,  moderately  thickened  and  lignified,  reacting  to 
phloroglucin. 
A  continuation  of  this  tube  with  the  root  in  place  is  shown  in 
Fig.  4,  ending  just  inside  the  pericycle.    Here  the  mestome  of  the 
