2o6  Standardization  of  Digitalis.  {^"'Ma^im*""* 
some  of  the  statements  of  Reed  and  Githens,  unsupported  by  experi- 
mental proof,  are  rather  at  variance  with  the  commonly  accepted 
views  regarding  the  pharmacology  of  digitalis. 
To  summarize  the  statements  of  the  authors  I  have  mentioned 
above,  we  learn  that: 
L  Frogs  vary  markedly  in  resistance  to  digitalis  poisoning.. 
11.  That  the  adoption  of  a  standard  is  unsafe  because  of  the 
uncertainty  regarding  the  strength  of  this  standard. 
in.  That  guinea-pigs  react  with  much  uniformity  to  digitalis. 
IV.  That  absorption  plays  an  important  part  in  the  frog 
methods. 
V.  That  guinea-pig  and  frog  methods  are  lethal  dose  methods ; 
death  in  both  cases  resulting  from  the  action  of  the  drug  on  the 
heart. 
As  suggested  by  Houghton,  crystalline  strophanthin,  also 
known  as  strophanthin  gratus  or  ouabain,  is  an  ideal  substance  for 
a  standard.  Possessing,  as  it  does,  the  characteristic  "  digitalis 
action  on  the  frog's  heart,  it  is  a  definite  chemical  compound,  and 
the  question  of  variability  of  strength  or  deterioration  does  not 
come  intO'  play.  By  means  of  this  ouabain,  each  frog  lot  can  be 
standardized,  and  the  possibility  of  error  arising  from  uncertain 
reaction  of  the  frog  eliminated. 
It  is  indeed  commendable  with  what  care  some  of  the  authors 
I  quoted  have  scrutinized  the  frog  methods  in  the  effort  to  discover 
defects  from  the  unfitness  oi  the  animal.  The  same  amount  of 
scrutiny  has  not,  apparently  been  bestowed  upon  the  guinea-pig. 
Reed  contents  himself  with  saying  that  this  animal  "  does  not 
appear  to  offer  so  wide  a  variation  " ;  Githens  ^  says  that  it  "  shows 
no  such  variation  " ;  while  the  Philadelphia  committee  modifies 
its  claim  as  to  constant  resistance  in  guinea-pigs  by  adding :  So 
far  as  is  known." 
In  this  connection,  it  is  of  interest  to  mention  some  of  the 
results  secured  by  Arms  ^  in  animal  inoculations. 
Two  pigs  inoculated  with  emulsion  of  nervous  tissue  from  rabid 
dog:  one  developed  typical  paralysis  on  nth  day;  second  showed 
no  evidences  of  injury  and  was  normal  at  autopsy  13  months  later. 
Two  pigs  inoculated  with  emulsion  from  another  rabid  dog;  one 
died  same  night;  other  showed  no  evidences  of  injury  and  examina- 
tion of  brain  was  negative  six  months  later.  The  following  day, 
a  third  pig  was  inoculated  with  emulsion  from  this  same  dog;  no 
