126 
Structure  of  Cimicifuga. 
( Am.  Jour.  Pharm. 
\      March,  1895. 
In  this  species  it  will  be  seen  that  the  number  of  secondary  xylem 
wedges  and  of  medullary  rays  corresponds  to  the  number  of  xylem 
rays  and  of  phloem  masses  in  the  primary  radial  bundle. 
The  root  thus  affords  us  the  best  characters  for  the  identification 
of  the  drug.    There  are  few  roots  in  which  the  most  characteristic 
Fig.  6. 
secondary  changes  that  occur  in  the  roots  of  dicotyls  are  traceable 
with  so  little  difficulty  as  in  this.  It  therefore  affords  an  especially 
good  example  for  the  young  microscopist  to  study. 
It  should  be  observed  also  that  the  number  of  rays  is  not  always 
constant  in  the  same  root.  It  may,  for  example,  be  triarch  at  the 
apex  and  tetrarch  near  its  base,  or  it  may  be  tetrarch  near  its  apex 
