Afl*bS£. ST'}     The  Rhubarbs  and  a  Probable  Adulterant.         1 3 1 
interested  in  the  subject,  however,  will  find  a  good  account  of  the 
plant  in  Professor  Trimble's  work  on  the  tannins. 
The  samples  of  Chinese  rhubarb  used  in  the  present  examination 
presented  the  usual  fusiform  outline  and  mottled  surface.  On  close 
examination  this  latter  effect  is  observed  to  be  due  to  alterations  of 
a  dirty  white  and  a  brownish-yellow  tissue,  and  in  these  colors  is 
particularly  observable  in  fresh  fractures  or  cuts.  If  such  a  surface 
be  moistened,  though,  the  white  is  observed  to  turn  a  light,  bright 
yellow,  and  the  former  yellow  to  a  striking  dull  orange  color,  thus 
darkening  the  whole  effect.  Somewhat  the  same  thing  happens  by 
exposure  to  the  air.  An  observation  of  a  freshly-cut  and  moistened 
surface  shows  that  the  tissues  in  numerous  places  are  aggregated 
into  contorted  groups,  to  which  effect  the  mottled  or  marbled 
appearance  is  due.  Thin  sections  show  that  the  lighter  ground- 
work tissue  is  composed  of  thin-walled  parenchyma  cells,  while  the 
dark  and  contorted  areas  are  principally  fibro- vascular  tissue.  The 
latter,  in  certain  forms  of  the  drug,  is  regularly  arranged  into  spots 
having  a  radiate  structure  and  forming  the  so-called  stellate  spots  or 
11  Maseru  "  of  the  Germans.  Recent  writers  state  that  these  are 
particularly  characteristic  of  the  Russian  variety,  which  is  no  longer 
on  the  market.  The  accompanying  drawing  {Fig.  /i,  adapted  from 
Berg,  illustrates  the  effect. 
Fig.  4. — Cross-section  of  Rheum,  after  Berg. 
This  peculiar  structure  is  due  to  the  method  of  growth,  whereby 
the  numerous  rudimentary  leaves  on  the  surface  of  the  rhizome 
leave  the  form  of  their  fibro-vascular  growth  as  a  permanent  record 
on  the  parent  stem.  In  the  specimens  examined  this  structure  did 
not  make  its  appearance,  and  I  think  it  will  be  found  that,  in  its 
typical  form,  it  rarely  does.    What  really  was  found  was  a  massed 
