488 
Silphium  Laciniatum,  Rosin  Weed. 
j  Am.  Jour.  Pliarm. 
j.       Oct.,  1881. 
Fig.  jB  is  a  loiigitudiiial  section  of  the  root,  and  shows  the  very 
irregular  course  of  the  simple  resin  ducts. 
Fig.  C  shows  one  of  the  pitted  ducts,  which  were  the  only  kind 
found,  although  some  twenty  specimens  of  the  root  were  examined. 
Root  of  Silphium  Laciniatum.  —  A  Transverse  section,  magnified, 
with  origin  of  a  rootlet.  C  Pitted  duct.  D  Transverse  section, 
natural  size. 
Fig.  D  is  a  cross  section  of  the  root,  natural  size,  from  which  the 
xiiiferent  magnified  sections  were  cut. 
Following  is  the  result  of  an  analysis  made  of  the  resinous  juice 
0 
