Am.  Jour.  Pharm. 
May,  1896. 
}    How  to  Distinguish  Viburnum  Barks. 
231 
ihe  forms  are  what  may  be  seen  if  thickness  of  fragment,  coloring 
matter  and  other  causes  do  not  prevent. 
Viburnum  Prunifolium,  Bark  of  the  Trunk. — A  brownish  or  red- 
dish-gray powder,  darker,  by  several  shades,  than  that  of  the  other 
varieties ;  taste  slightly  bitter.  Under  the  microscope  the  absence  of 
fibrous  tissue  is  noticeable.  The  stone-cells  are  readily  distinguished 
and  quite  numerous,  as  they  are  in  the  bark  of  the  twigs  and  in  the 
bark  of  the  root.    See  Fig.  6. 
Fig.  7. — Viburnum  opulus.  Powdered  bark,  X  400  :  bast  fibres  in  bark, 
situated  in  middle  bark;  b}  middle  bark  cells;  c,  outer  layer  of  middle  bark;  d, 
fragments  of  cork  layer. 
Viburnum  Prunifolium,  Bark  of  the  Twigs. — A  light  brownish- 
gray  powder,  very  easily  pulverized.  When  viewed  under  the 
microscope  there  is  a  close  resemblance  to  the  trunk  bark,  and  the 
difference  seems  too  slight  to  be  shown  in  a  drawing.  The  color  is 
quite  characteristic. 
Viburnum.  Prunifolium,  Bark  of  the  Root. — A  grayish  powder. 
Under  the  microscope  a  sharp  distinction  from  the  above  is  apparent. 
It  displays  a  great  number  of  starch  granules,  which,  of  course,  is 
more  pronounced  by  treatment  with  iodine  T.  S.    The  difference 
DESCRIPTION  OF  THE  POWDERS. 
ou 
