'Amj^y,rx8P76arm*}      Rhubarb  and  Rheum  Officinale,  309 
ondary  roots  show  the  ordinary  regular  structure  of  this  kind  of  axis, 
and  no  trace  of  the  star-like  spots  or  knots  which  give  the  drug  its 
special  appearance. 
Dr.  Schmitz,  of  Halle,1  was  the  first  to  point  out  the  signification  of 
these  knots,  and  to  show  that  the  official  rhubarb  is  a  root  stock,  which 
for  one  year  grows  as  a  tuberous,  thickened  short  stem,  producing  a 
flower-stalk  that  dies  off"  completely,  and  that  on  this  short  stem  ap- 
peared numerous  lateral  buds  that  grow  in  a  similar  manner  to  the  stem 
from  which  they  are  produced.  The  knots,  however,  which  Dr. 
•Schmitz  looks  upon  as  starting  from  the  medulla,  appear,  Professor 
Fluckiger  thinks,  to  be  related  to  the  vascular  bundles  of  the  leaf.  In 
consequence  of  the  close  arrangement  of  the  leaves  round  the  root- 
stock  the  irregular  net-like  interwoven  fibres  stand  very  close  together, 
so  that  a  tranverse  section  at  the  base  of  the  leaf-stalks  also  give  the 
characteristic  circular  distribution  of  the  knots.  The  fibres  increase  in 
thickness  independently,  the  inner  portion  of  each  separate  knot  con- 
sisting of  parenchyma,  which  behaves  as  bark  tissue,  and  is  surrounded 
by  a  cambium  ring.  Outside  the  latter  the  fibre  has  the  character  of 
the  woody  portion  (xylem)  to  the  extent  that  well  perfected  vessels  ap- 
pear in  it. 
The  knots  are,  however,  by  no  means  peculiar  to  the  true  officinal 
rhubarb,  as  they  appear  also  in  the  so-called  European  rhubarbs.  But 
there  is  this  very  great  difference,  that  they  are  to  be  found  much  more 
plentifully  and  in  a  dense  though  irregularly  arranged  zone  in  the  true 
officinal  drug  as  well  as  in  the  root-stock  of  Rheum  officinale.  But  a 
small  number  of  isolated  knots  occur  not  unfrequently  in  the  French  or 
English  rhubarbs.  This  fact  led  Schmitz  to  say  that  the  root-stock  of 
R.  Emodiy  Wallich,  also  possesses  the  characteristic  markings  of  true 
Chinese  rhubarb,  a  statement  that  the  author  thinks  needs  limitation. 
Especially,  a  remark  connected  with  this,  that  probably  a  portion  of 
the  Himalaya  rhubarb  obtained  in  the  country  of  R.  Emodi,  might  be 
derived  from  that  plant,  is,  Professor  Fluckiger  thinks,  put  beyond  con- 
sideration by  the  fact  that  no  Himalayan  rhubarb  occurs  in  European 
commerce.  After  careful  consideration  of  the  English  and  Indian 
markets,  Fluckiger  and  Hanbury  felt  bound  not  to  perpetuate  the  name 
*'  Himalayan  rhubarb  "  in  their  "  Pharmacographia."  Together  with 
innumerable  other  drugs,  probably  the  roots  of  R.  Emodi  and  other 
1  Session  of  the  Naturforscher  Gesellchaft  at  Halle,  Dec.  ia,  1874. 
