Am.  Jour.  Pharm. 
May,  1896. 
}    How  to  Distinguish  Viburnum  Barks. 
229 
mentioned.  Growing  upon  the  surface  of  the  leaves  are  numerous 
hairs  which  are  multicellular  and  characteristic  ;  these  in  the  powder 
are  not  completely  destroyed,  as  are  not  other  important  histologi- 
cal elements.  Even  the  class  of  powders  known  as  impalpable, 
while  they  present  greater  difficulty,  there  is  almost  always  found 
in  them  some  elements  and  fragments  whose  characteristics  are  con- 
stant and  sharp,  which  the  pulverization  has  not  greatly  modified. 
If,  perchance,  they  are  broken  into  fragments,  the  fragments  retain 
characteristic  markings  and  serve  as  means  of  identification.  The 
following  procedure  in  the  examination  may  be  modified  to  suit 
Fig-5> — Viburnum  prunifolium.  Powdered  root-bark,  X400:  a,  stone-cells; 
b,  inner  bark  cells;  c,  middle  bark  cells;  d>  inner  cells  of  middle  bark;  e,  starch 
grains;     fragments  of  cork  layer. 
certain  different  powders,  but  it  is  a  general  direction  which  will 
serve  in  most  cases.  Add  a  few  particles  of  the  well-mixed  pow- 
der in  a  porcelain  capsule  containing  a  mixture  of  alcohol,  glycerin 
and  water;  after  about  two  hours'  maceration,  examination  is  com- 
menced, when  the  nature  of  the  elements  enclosed  in  the  cells,  which 
have  not  been  destroyed  by  pulverization,  can  be  determined  (starch, 
aleurone,  inulin,  etc.).  To  render  more  apparent  the  forms  of  the 
various  separated  elements  and  fragments,  boil  the  powder  in  an 
alkaline  water.  In  this  manner  one  can  distinguish  more  quickly 
and  more  completely  all  of  these  histological  peculiarities,  which 
