158     GROWTH  AND  PREPARATION  OF  RHUBARB  IN  CHINA. 
In  Sz-chuen,  however,  the  quality  appears  to  vary,  that  which 
grows  in  the  west  and  is  dried  in  the  shade  being  better  than  that 
which  is  dried  in  the  sun  in  the  north  of  the  same  province  ; 
while  that  which  is  dried  by  artificial  heat  is  said  to  be  slightly 
charred.  Tau-hung-king,  who  makes  the  foregoing  remark,  adds 
that  Sz-chuen  rhubarb  is  not  equal  in  quality  to  that  of  Lung-si 
in  Shen-si ;  that  it  is  black  in  color  and  very  bitter.  This,  how- 
ever, is  altogether  denied  by  Kung.  Su-sung  also  says  that  Sz- 
chuen  rhubarb  is  fine-grained,  and  next  comes  that  of  Shen-si. 
He  adds,  however,  that  the  value  of  these  two  kinds  is  the  same. 
Sung-ki,  who  lived  between  A.  D.  1000  and  1270,  says  that  in  his 
time  Lung-si  (Shen-si)  rhubarb  was  considered  the  best. 
Notwithstanding  the  want  of  precision  and  agreement  in  the 
above  statements,  I  think  that,  taken  in  connection  with  the  ex- 
tracts from  "  The  Rules  of  the  Drug  Trade  in  China  "  and  from 
"The  Chinese  Commercial  Guide,"  they  will  warrant  the  follow- 
ing— 
Conclusions. 
1.  Rhubarb  grows  in  many  parts  of  the  Chinese  empire,  but 
chiefly  in  Kan-suh,  south  of  Mongolia,  about  Ko-ko-nor,  and  on 
the  Kawn-lun  mountains,  which  forms  the  northern  boundary  of 
Thibet ;  and  also  in  the  provinces  of  Shen-si,  Shan-si,  Ho-nan, 
and  Sz-cheun.  From  the  former  districts  the  dried  root  reaches 
Europe  at  present  by  way  of  Moscow ;  from  the  latter  it  is  conveyed 
along  the  Yellow  and  Yang-tse  rivers  to  the  ports  of  Shanghai 
and  Hankow. 
2.  The  descriptions  of  the  plant  are  not  sufficiently  precise  to 
show  whether  the  roots  of  only  one,  or  of  more  than  one  species 
are  collected  for  medicinal  use.  Any  real  differences  in  the  de- 
scriptions are  easily  accounted  for  on  the  latter  supposition. 
The  contradictions,  however,  are  more  apparent  than  real.  Ac- 
cording to  Kung  the  root  is  red,  while  Su-sung  says  that  it  is 
covered  with  a  black  skin,  which  is  taken  off.  The  black  skin 
consists,  as  any  one  may  see  by  examining  the  root  of  Rheum 
palmatum  in  the  winter,  of  the  black  decayed  bases  of  the 
sheathing  petioles,  which  cover  the  rhizome,  so  that  its  red  color 
is  not  apparent  until  these  are  removed.  The  difference  in  the 
height  of  the  plant  and  the  color  of  the  leaves  probably  depends 
