ADe'imbeiu899m*}       Valuation  of  Drugs  and  Foods.  597 
sensations  afforded  by  the  two  points  are  blended  into  one,  and  the 
patient  says  that  but  one  point  is  felt.  The  distance  between  the 
two  points,  indicated  on  a  scale  attached  to  the  instrument,  is  in- 
versely proportional  to  the  delicacy  of  tactile  sensibility.  Of  course 
it  is  most  used  in  hunting  for  anesthetic  or  hypesthetic  (lessened 
sensibility)  patches  in  the  skin  in  suspected  hysteria,  but  it  has  a 
distinct  field  of  pharmacologic  use  in  estimating  the  effects  of  local 
anesthetics,  particularly  on  mucous  membranes  or  over  cutaneous 
areas  subjected  to  hypodermic  injections  of  the  various  candidates 
for  anesthetic  honors.  Surely  we  must  bear  in  mind  that  the  world 
is  not  standing  still  and  that  the  old  physiology  and  physiological 
methods,  based  on  theories  which  have  not  been  satisfactorily  dem- 
onstrated, are  giving  gradually  way  to  the  newer  methods  of  research 
based  on  the  results  and  experience  of  recent  years. 
We  need  not  wonder  that  there  are  many  who  do  not  as  yet  com- 
prehend the  importance  of  biological  assay,  for  it  must  be  borne  in 
mind  that  this  subject  is  still  in  its  infancy,  and  that  it  is  only  with- 
in the  past  few  years  that  it  has  received  any  consideration  at  the 
hands  of  experimental  physiologists. 
(4)  The  results  of  the  clinician  represent  those  of  experiment 
upon  man  in  disease.  It  may  be  said  that  the  experience 
of  the  ages  has  come  down  to  us,  each  race  and  tribe  con- 
tributing something  of  value.  The  Indian  of  Peru  has  taught  us 
the  value  of  cinchona  and  coca.  The  Hottentots,  from  their  ex- 
perience, found  out  the  value  of  buchu,  and  examples  of  this  kind 
can  be  multiplied.  As  new  localities  are  explored,  new  drugs  and 
foods  are  discovered  which  have  been  employed  by  the  native 
inhabitants.  Many  more,  however,  are  the  discoveries  of  the  pres- 
ent day  in  the  laboratory  of  the  chemist  of  either  new  constit- 
uents in  plants  or  new  synthetics,  created  by  his  synthesis,  from  other 
materials.  The  value  of  these  new  medicaments,  however,  is  now 
first  ascertained  upon  some  of  the  lower  animals,  and  it  may  be  that 
experiments  upon  plants  will  show  that  some  of  this  work,  in  at 
least  determining  the  toxicity  of  the  new  compounds,  may  be  satis- 
factorily done  upon  either  germinating  seeds  or  upon  algae. 
V.  OPTICAL  METHODS. 
The  valuation  of  some  drugs,  and  the  products  obtained  from 
them,  by  means  of  the  microscope,  spectroscope  and  polariscope  is 
