130         The  Rhubarbs  and  a  Probable  Adulterant.  {AVa°rc£;?8h98rm" 
suits  obtained  on  account  of  the  limited  number  of  specimens.  For 
the  same  reason  the  paper  can  be  considered  merely  a  preliminary 
one,  subject  to  such  corrections  as  more  detailed  study  of  the  sub- 
ject may  indicate.  The  purpose  for  which  the  investigation  has 
been  conducted  is  to  discover,  if  possible,  some  test  whereby  the 
substitution  of  inferior  grades  of  rhubarb  for  the  better  one,  or  ad- 
mixture with  a  foreign  drug,  may  be  detected. 
A  study  of  the  true  Rheum  shows  that  it  is  characterized  by  seve- 
ral features  peculiarly  its  own.  Yet  despite  this  there  is  no  exact 
information,  so  far  as  I  know,  concerning  the  true  botanical  origin 
of  the  drug.  It  is  commonly  ascribed  to  R.  officinale  and  R.  pal- 
matum,  and  there  is  little  doubt  that  one  or  both  of  these  contribute 
the  major  portion  of  the  commercial  rhubarb.  If  but  one  be 
the  source,  then  which  it  is,  I  think,  cannot  be  said  to  a  certainty. 
Rheum  officinale  is,  perhaps,  the  one  usually  considered  as  furnishing 
the  true  rhubarb.  It  is  a  native  of  Southeastern  Thibet  and  possibly 
of  China  also.  In  appearance  it  considerably  resembles  the  ordinary 
garden  rhubarb,  with  which  it  has  been  cultivated  in  Europe,  but 
differs  from  it  in  several  particulars.  R.  palmalum  is  indigenous  to 
Northwestern  China.  It  first  became  known  to  Europeans  in  1750, 
and  received  a  description  from  Linnaeus  in  1 762.  Like  R.  officinale  it 
has  been  cultivated  in  foreign  countries,  the  first  having  been  grown 
in  England  in  1765. 
Rheum  rhaponticum,  European  rhubarb,  is  the  source  of  the  cheap 
variety  of  rhubarb.  It  is  a  native  of  Southern  Siberia,  and  is  closely 
related  to  R.  undulatum,  the  common  garden  variety.  Like  that, 
too,  it  is  easily  cultivated,  and  the  commercial  source  of  the  drug  is 
the  gardens  of  Europe. 
These  various  kinds  of  rhubarb,  although  comparatively  recent 
additions  to  the  materia  medica  of  the  Occident,  have  long  been 
known  and  used  by  the  Chinese.  Specific  mention  of  the  drug  is 
found  in  their  writings  as  far  back  as  2700  B.C.  They  still  collect 
and  prepare  it  as  they  did  in  the  early  days,  and  Chinese  rhubarb  is 
the  synonym  for  the  best  quality  of  the  commercial  article. 
Rumex  hymenosepalus  is  a  member  of  the  same  natural  order  as 
Rheum,  but  is  a  native  of  the  western  hemisphere.  It  has  recently 
come  into  prominence  because  of  the  use  to  which  its  tannic  acid 
has  been  applied.  Since  this  article  has  to  do  chiefly  with  the  rhu- 
barbs, no  further  treatment  will  be  accorded  the  canaigre.  Those 
