530  Powdered  Vegetable  Drugs.  {A  octobeM89?m" 
In  Scilla,  the  number  of  cells  with  groups  of  acicular  crystals 
are  best  selected. 
In  Belladonna  radix,  the  starch  grains  are  most  easily  used,  but  it 
must  be  borne  in  mind  that  there  are  several  kinds  of  Belladonna 
root  in  the  market. 
In  Nux  Vomica,  the  lignified  hairs  are  most  characteristic. 
In  Rheum,  the  large  "rosette-shaped  "  crystals  of  calcium  oxalate 
are  best  selected. 
In  Caryophy litis y  the  oil-secreting  reservoirs  are  used. 
In  Cinnamomitm,  the  groups  of  stone  cells  or  starch  grains  are 
characteristic,  taken  in  connection  with  the  presence  or  absence  of 
cork  cells. 
In  Sarsaparilla,  the  starch  grains  are  considered  after  the  kind  of 
root  has  been  ascertained. 
X 
X 
X 
X 
X 
Fig.  2. 
In  Glycyrrhiza,  the  characteristic  fibres  with  calcium  oxalate  crys- 
tals adjoining  them,  or  the  starch  grains,  are  employed. 
(9)  The  method  consists  in  counting  the  number  of  characteristic 
elements  in  several  portions  of  the  slide,  and  may  be  performed  in 
several  ways : 
(a)  By  the  use  of  an  ocular  micrometer  ruled  in  100  square  millL 
meters,  as  proposed  in  1894.  Five  portions,  at  least,  of  the  mount 
are  examined,  as  in  the  places  marked  X  (Fig.  2). 
The  number  of  characteristic  elements  that  appear  in  each  of 
these  places  in  certain  portions  of  the  ocular  micrometer  are  counted, 
as,  for  instance,  those  that  appear  in  the  square  millimeters  marked 
X  (Fig.  j). 
The  low  power  to  -inch  objective)  is  used  in  some  cases,  as 
in  the  estimation  of  rheum,  scilla,  etc.;  but  in  most  instances,  espe- 
cially when  starch  grains  are  to  be  counted,  a  higher  power  (%  to 
|-inch  objective)  is  preferred,  as  in  Belladonnae  radix,  Zingiber,  etc. 
