A  ja^aryfim"1}    Pharmacological  Assay  of  Drugs.  3. 
side  and  estimating  its  amount ;  and  the  total  amount  of  glucosides 
is  of  no  value  as  an  indication  of  its  strength,  for  they  vary  in 
activity  from  the  practically  innocuous  digitonin  to  the  very  poison- 
ous digitoxin.  An  attempt  has  been  made  to  assay  the  drug  by 
the  content  of  digitoxin,  but  apart  from  the  difficulty  of  the  pro- 
cess, there  are  other  glucosides  present  which  are  equally  important 
from  the  practitioner's  standpoint,  and  these  may  vary  equally  with 
digitoxin.  The  chemical  assay  of  digitalis  may  therefore  be  dis- 
missed as  impracticable  at  present,  and  in  all  probability  for  many 
years  to  come. 
A  new  method  of  assay  has,  however,  been  introduced  in  the 
last  few  years  and  has  been  adapted  to  practical  pharmacy  in  this 
country.1  I  refer  to  the  pharmacological  assay  or  the  estimation  of 
the  therapeutic  activity  of  a  drug  by  its  effects  on  the  lower  animals, 
A  certain  prejudice,  which  seems  to  exist  in  some  minds  against  this 
method,  may  perhaps  be  ascribed  to  the  innate  conservatism  of  the 
medical  and  pharmaceutical  professions,  and  to  the  belief  that 
results  on  animals  cannot  be  used  as  a  basis  for  application  in 
therapeutics.  As  to  the  latter  point  it  need  only  be  mentioned  that 
almost  all  the  advance  of  recent  years  in  medicine  is  based  upon 
experiments  made  on  our  humbler  relatives,  and  that  by  therapeutic 
assay  the  absolute  dose  is  not  estimated  from  animals  to  man  but 
merely  the  relative  activity.  To  illustrate  this  by  an  example  :: 
if  a  tincture  (A)  of  digitalis  is  found  to  induce  symptoms  in  a  dog 
of  30  pounds  in  the  dose  of  1  c.c,  we  cannot  infer  that  5  c.c.  will; 
be  equally  effective  in  a  man  of  150  pounds.  But  if  we  find  that 
the  dose  in  man  is  2  c.c.  by  actual  clinical  experience  and  now 
investigate  a  second  tincture  (B)  on  the  dog  and  find  that  2  c.c.  are 
required  to  induce  the  same  symptoms  as  1  c.c  of  A,  we  cao 
assume  with  some  probability  that  the  therapeutic  dose  of  B  in 
man  will  be  4  c.c.  Without  the  preliminary  examination  on  the 
dog  the  strength  of  the  remedy  could  be  ascertained  only  by 
clinical  examinations  on  patients,  and  this  involves  much  time  and 
in  some  cases  would  not  be  devoid  of  danger.  Before  examining  the 
limitations  of  this  new  method  of  assay  it  may  be  necessary  to 
examine  its  relation  to  the  chemical  method.    And  when  the  latter 
1  It  is  of  interest  to  find  Professor  Gottlieb,  of  Heidelberg,  advocating  the 
pharmacological  assay  of  digitalis  at  the  meeting  of  the  Congress  of  Physi- 
cians at  Wiesbaden  in  April,  1901. 
