292  Economic  Botany.  {AmjSe"i8M.arm' 
by  man,  either  civilized  or  savage.  Of  these,  probably  the  great 
majority  are  worthless  or  nearly  so  for  the  purposes  for  which  they 
are  employed.  Even  of  those  mentioned  in  the  Dispensatory,  only 
244  are  regarded  as  of  sufficient  value  to  be  given  a  place  in  the 
Pharmacopoeia  of  1890,  and  some  of  these,  I  am  sure,  are  retained, 
not  because  of  their  intrinsic  worth,  so  much  as  because  they  are 
extensively  used. 
But  taking  the  pharmacopceial  plants  as  representing  fairly  well 
those  at  present  approved  by  the  intelligence  of  mankind,  how 
small  a  proportion  must  it  be  of  those  that  will  ultimately  be 
proved  valuable  !  How  small  a  portion  of  the  earth's  flora  has  been 
investigated  even  superficially,  with  reference  either  to  medicinal 
constituents  or  physiological  action !  Even  among  the  drugs  that 
have  been  studied  to  some  extent  with  reference  to  these  points,  in 
how  few  cases  has  the  work  been  done  in  an  exhaustive  or  thorough 
way!  The  greater  the  amount  of  study  given  to  the  chemical 
principles  of  plants,  the  more  we  realize  how  endless  is  the  variety 
and  how  great  the  probabilities  are  that  vast  numbers  of  undiscov- 
ered ones  yet  exist  that  may  prove  of  inestimable  value  to  mankind. 
In  the  line  of  cultivation  of  medicinal  plants,  with  the  view  to 
their  improvement,  just  enough  has  been  done  to  prove  the  import- 
ance of  further  work  in  the  same  direction.  Owing  to  the  imminent 
danger  that  the  destructive  methods  of  gathering  Cinchona  barks 
in  South  America  would  soon  lead  to  the  extermination  of  these 
trees,  the  necessity  for  cultivating  them  arose  a  few  decades  ago,  and 
experiments  were  begun  in  India  and  elsewhere  on  a  large  scale,  and 
with  most  interesting  and  suggestive  results.  It  has  been  found 
that  by  careful  selection  of  favorable  species,  by  crossing  and  again 
selecting  favorable  variations,  barks  may  be  produced  which  yield 
double  or  even  treble  the  quantity  of  alkaloids  produced  by  the  best 
varieties  from  wild  trees  in  their  native  Andes.  Therefore,  by  pre- 
cisely the  methods  employed  by  the  floriculturist  and  pomologist, 
the  drug  gardener  may  improve  the  medicinal  plants  he  cultivates. 
Only  one  other  line  of  development  will  I  occupy  a  moment  in 
directing  attention  to,  and  that  is,  the  possibilities  that  lie  in  the 
micro-chemical  study  of  drugs.  The  methods  of  macro-chemical 
investigation  are  under  such  headway  that  creditable  work  is  being 
done  by  them  in  chemical  laboratories  the  world  over ;  but  only 
quite  recently  have  micro-chemical  methods  risen  to  prominence.  It 
