412       ON  THE  COLLECTION  OF  SOME  INDIGENOUS  DRUGS. 
lecting  wild  cherry  bark  is  in  the  fall,  September  or  October,  as 
then  it  contains  a  larger  proportion  of  amygdalin,  and  conse- 
quently yields  more  hydrocyanic  acid  and  volatile  oil  than  in 
the  spring  or  summer. 
American  Senna. — According  to  the  late  Dr.  R.  E.  Griffith, 
(Medical  Botany,  p.  261,)  American  senna  leaves  should  be  col- 
lected when  the  fruit  is  ripe  or  nearly  ripe,  which  is  in  September. 
Dandelion  Root — Roots  generally,  as  is  well  known  to  many, 
should  be  collected  in  the  fall  months,  and  before  frost  sets  in. 
This  is  especially  true  of  taraxacum,  which  in  October  has  its 
juices  well  stored  with  the  bitter  principle,  the  presence  of  which 
is  usually  considered  an  index  of  medicinal  power,  although  we 
believe  physicians  have  yet  to  prove  on  what  constituent  of  the 
plant  that  power  depends. 
Pith  of  Sassafras — An  experienced  collector  of  medicinal 
plants  informs  us,  that  pith  of  sassafras  should  not  be  collected 
until  after  the  15th  of  October,  as  when  removed  before  that 
time  it  frequently  assumes  a  brown  hue,  probably  from  the  pre- 
sence of  juices  subsequently  removed  by  absorption,  as  the  period 
of  suspended  vegetation  approaches. 
Diospyros —  Unripe  Persimmons — Formerly  the  bark  of  the 
persimmon  tree  was  the  part  made  officinal,  but  in  the  Pharma- 
copoeia of  1850,  the  unripe  fruit  was  substituted,  which  is  now 
the  proper  officinal  substance  to  be  dispensed  under  the  name 
"  Diospyros."  The  fruit  should  be  collected  when  it  has  at- 
tained its  full  size,  and  on  the  point  of  changing  color,  but  be- 
fore the  conversion  of  tannin  into  sugar  has  commenced,  a  change 
rapidly  promoted  by  frost.  In  September  is  the  time  for  the 
collection  of  this  fruit.  When  not  used  fresh,  it  should  be  sliced 
and  dried  in  a  warm  situation  with  free  circulation  of  air. 
Dulcamara, — The  terminal  twigs  of  bitter  sweet  should  be 
collected  in  October,  or  after  the  fall  of  the  leaves,  and,  for  conve- 
nience of  division  by  the  mill  or  pestle,  should  be  cut  in  short 
transverse  slices,  not  over  half  an  inch  in  length  ;  a  treatment 
which  also  favors  their  dessication. 
Ulmus. — Slippery  elm  bark,  as  found  in  the  market,  varies 
much  in  appearance  and  quality ;  sometimes  its  color  is  uniform 
throughout,  fibrous,  and  full  of  mucilage,  with  but  little  astrin- 
gency.    At  other  times  its  fibrous  character  is  wanting,  and  the 
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