I04  Biological  Standardisation  of  Drugs.    { ^'^ardi,*  im" 
of  procedure  is  essentially  the  same  as  that  suggested  by  Famulener 
and  Lyons  ^  in  which  permanent  systole  of  the  frog's  ventricle 
at  the  end  of  exactly  one  hour  is  taken  as  the  end  reaction.  Some 
slight  modifications  have  been  •  made,  the  chief  of  which  is  that 
the  assays  are  all  carried  out  at  a  constant  temperature  as  it  is 
believed  that  this  precaution  results  in  greater  accuracy.  The 
drug  is  injected  through  the  mouth  into  the  anterior  lymph  sac 
of  the  intact  frog  (Rana  pipiens)  and  at  the  end  of  an  hour  the 
animal  is  pithed  (both  brain  and  cord)  and  the  thorax  opened. 
The  condition  of  the  heart  is  then  noted  and  a  smaller  or  larger 
dose  is  injected  as  indicated.  To  hasten  the  assay  a  series  of 
three  frogs  is  usually  given  doses  which  vary  quite  widely  and 
an  approximate  dose  is  estimated  from  these  preliminary  results. 
By  successively  narrowing  the  limits  of  dosage  that  amount  just 
necessary  to  produce  the  end  reaction  may  be  determined  by  the 
use  of  from  8  to  12  frogs. 
The  method  has  the  advantage  of  comparative  simplicity  so 
far  as  operative  technique  is  concerned.  The  animals  are  always  easily 
obtained  which  is  a  very  important  consideration  and  if  the  storage 
tanks  be  kept  at  a  suitable  temperature  (10°  to  15°  centigrade) 
they  remain  active  and  healthy  for  months.  In  this  connection 
it  is  worth  while  calling  attention  to  the  difificulty  of  obtaining 
a  suitable  number  of  mammals,  especially  cats,  rabbits,  or  dogs, 
for  carrying  out  such  tests  on  warm  blooded  animals  when  a  large 
number  of  assays  are  to  be  made.  Of  less  importance  also  is  that 
of  cost.  Frogs  for  each  assay  will  cost  approximately  fifty  cents. 
If  mammals  are  used,  on  the  basis  that  at  least  three  to  five  should 
be  used  for  each  assay,  the  cost  would  be  from  two  to  three 
dollars  while  tO'  this  would  be  added  the  expense  of  food  supplies, 
etc.,  which  in  the  case  of  the  higher  animals  is  a  considerable 
item. 
While  thus  expressing  my  belief  in  the  frog  as  a  suitable  and, 
despite  certain  elemental  precautions,  a  convenient  animal  for  assay 
purposes  it  has  never  been  shown  to  what  degree  biological  assays, 
using  either  frogs  or  other  animals,  were  accurate  and  especially 
as  showing  the  therapeutic  potency  of  a  given  preparation. 
Unknowns  made  up  by  a  chemist  in  the  Division  of  Pharma- 
cology were  assayed  and  the  results  of  these  assays  are  grouped 
'Famulener  and  Lyons:    Proc.  Am.  Pharm.  Ass.,  1902,  50,  415. 
