536 
Methods  for  Digitalis  Assay. 
Am.  Jour.  Pharm. 
August,  1920. 
of  digitalis  on  mammalian  heart  therefore  resemble  in  general 
those  observed  in  the  frog's.  The  contraction  is  not  pro- 
longed, however,  as  in  the  latter  and  the  inhibitory  mechanism  plays 
a  more  important  role.  .  .  .  The  heart  in  mammals  is  generally 
found  in  a  condition  of  diastole  in  cases  of  fatal  poisoning  and 
this  has  been  supposed  to  indicate  a  fundamental  difference  in  the 
action  of  digitalis  on  the  amphibian  and  the  mammalian  heart.  The 
dilatation  is  not,  however,  a  direct  result  of  the  digitalis  but  is  proba- 
bly induced  by  the  poisons  formed  in  the  heart  by  its  own  activity." 
It  is  evident,  therefore,  that  the  frog  shows  a  typical  effect  of 
digitalis  just  as  distinctly  as  the  mammal,  that  it  can  be  used  in 
numbers  economically  impossible  in  comparison  with  cats  or  dogs 
and  thus  overcome  the  factor  of  individual  variations  that  the  digi- 
talis action  differs  in  no  material  respect  from  that  on  mammals. 
The  very  fact  that  the  science  of  Pharmacology  has  made  such 
wondrous  strides  is  evidence  that  the  action  of  drugs  on  the  human 
may  be  deduced  from  that  on  the  lower  animals. 
The  very  fact  that  a  system  of  dosage  has  been  worked  out  for 
the  powerful  drugs  shows  that  their  action  is  measurable  by  the 
effects  produced. 
Few,  however,  seriously  claim  to  be  able  to  deduce  human  dosage 
of  a  new  drug  from  its  effects  on  experimental  animals,  except  in  the 
most  superficial  way,  and  with  our  present  knowledge  any  such  at- 
tempt will  probably  lead  to  failure. 
It  is,  on  the  other  hand,  common  laboratory  experience  to  obtain 
practical  working  information  in  regard  to  a  new  drug  by  comparing 
the  intensity  of  its  effects  with  that  of  a  similar  known  drug.  If, 
for  example,  a  special  preparation  of  digitalis  such  as  an  active 
principle  is  produced,  its  good  and  bad  properties  can  readily  be 
deduced  for  human  medication  by  comparing  it  with  Tr.  Digitalis 
on  laboratory  animals. 
Or  an  entirely  new  local  anesthetic  can  be  compared  with  cocaine 
on  animals  and  thus  obtain  actual  data  as  to  its  effectiveness  under 
most  conditions  and  its  comparative  toxicity,  absorbability  and 
rate  of  elimination. 
Pharmacology  is  the  study  of  the  action  of  drugs  on  the  lower 
animals  by  which  much  can  be  learned  as  to  the  adaptability  of 
drugs  in  therapy  and  their  mode  of  action,  their  advantages  and 
disadvantages  in  comparison  with  others  of  similar  character. 
Pharmacological  assaying  is  the  application  of  this  information 
