52  Pharmacognosy  and  the  US.P.  {Ais£Sh^SS^ 
are  problems  at  every  point  in  the  ofttimes  circuitous  route  which 
the  drug  travels  before  reaching  its  final  destination  in  the  finished 
preparation.  In  addition  to  the  field  problems,  as  those  involving 
the  determination  of  the  identity  of  the  plants  and  variation  in  the 
constituents  at  different  seasons  of  the  year,  there  are  also  other 
factors  of  which  cognizance  must  be  taken  that  influence  the  quality 
and  appearance  of  vegetable  drugs,  as  the  degree  of  skill  used  in  the 
drying  and  curing  of  the  drugs ;  the  proportion  of  other  plant  parts, 
as  of  stems  attached  to  roots ;  the  manner  and  length  of  time  of 
keeping;  and  attacks  of  fungi  and  insects,  etc.  We  may  say,  there- 
fore, that  pharmacognosy  begins  with  the  study  of  the  plants  yield- 
ing vegetable  drugs  and  ends  with  the  determination  not  alone  of 
their  identity  but  of  their  quality  also. 
When  one  considers  that  about  70  per  cent,  of  the  articles  in- 
cluded in  the  Pharmacopoeia  are  vegetable  drugs,  their  constituents, 
or  their  preparations,  it  is  seen  that  the  users  of  the  Pharmacopoeia 
must  have  a  knowledge  of  pharmacognosy,  and  that  the  physician  is 
directly  dependent  upon  the  work  of  the  pharmacognosist  for  the 
therapeutic  efficiency  of  many  of  the  most  important  medicines  which 
he  prescribes.  It  matters  not  how  perfect  the  methods  for  making 
preparations  are  if  the  materials  used  in  their  preparation  are 
spurious,  worthless,  or  vary  in  quality  to  a  considerable  extent. 
There  is  no  doubt  that  many  useful  drugs  and  their  preparations 
have  become  and  are  becoming  obsolete  for  the  reason  that  other 
drugs  which  are  inert  or  have  different  properties  have  been  or  are 
being  substituted  for  them.  Such  a  condition  not  only  baffles  the 
efforts  of  the  therapeutist  but  also  tends  to  deprive  him  of  remedies 
which  heretofore  were  considered  to  have  certain  valuable  proper- 
ties. But  some  will  say  that  the  drugs  are  becoming  scarce.  This 
is  true  in  some  instances,  but  instead  of  simplifying  the  question, 
renders  it  more  complicated  in  that  the  necessity  arises  for  detecting 
the  spurious  substitutes  that  are  frequently  admixed  with  the  gen- 
uine drug  or  even  entirely  replace  it. 
THE  U.  S.  PHARMACOPOEIA. 
While  it  is  not  possible  to  consider  all  the  various  phases  of 
pharmacognosy  in  the  Pharmacopoeia,  it  is  desirable  to  give  defini- 
tions and  descriptions  of  the  official  vegetable  drugs  which  are 
adequate  for  the  establishment  of  their  identity  and  efficiency.  In 
other  words,  it  is  the  results  of  the  studies  in  applied  pharmacog- 
