Am.  Jour.  Pharm.  / 
August,  1910.  | 
Standardization  of  Drugs. 
363 
The  difference  between  the  amount  of  crystalline  ouabain  actually 
used  to  complete  the  assay  and  0.1  mg.  per  kg.  of  animal  (the 
amount  which  would  have  been  required  in  the  absence  of  the  digi- 
talis body),  represents  the  activity  of  the  digitalis  used. 
The  following  example  will  illustrate  the  mode  of  computing  the 
activity  of  the  digitalis  body  tested :  A  tincture  representing  70  mgs. 
of  digitalis  per  kg.  of  cat  was  injected  into  the  femoral  vein  and 
after  twenty  minutes  the  injection  of  a  solution  of  ouabain  was 
begun.  The  animal  died  with  the  typical  symptoms  of  digitalis  poi- 
soning when  0.0142  mg.  of  the  crystalline  ouabain  per  kg.  had  been 
injected.  The  difference  between  0.0142  mg.  and  0.1  mg.  (which 
would  have  been  required  had  the  ouabain  been  used  alone)  is 
0.0858  mg.  or  85.8  per  cent,  of  a  cat  unit,  hence  70  mgs.  of  digitalis 
equals  85.8  per  cent,  of  a  cat  unit,  and  81.6  mgs.  of  the  digitalis 
equals  one  cat  unit.  A  duplicate  experiment  gave  81.8  mgs.  of  digi- 
talis. That  the  results  obtained  by  the  modified  technic  are  more 
accurate  than  those  with  the  continuous  injection  of  the  digitalis 
alone  is  shown  by  a  comparison  of  the  results  of  the  following  experi- 
ments intended  to  fix  the  minimal  lethal  dose  of  digitalis  by  the 
vein  with  those  given  in  Table  III. 
2  /24/'io.    Male  cat,  Wt.  3.65  kgs. 
10.30  a. m.  Injected  0.085  Gm.  digitalis  per  kg.  by  vein  at  once. 
10.45  A-M-  Emesis.    Cat  lived  over  7  hours,  but  died  during 
the  night. 
4/9/' 10.    Female  cat,  Wt.  2.02  kgs. 
1 1.4.0  a.m.  Injected  0.080  Gm.  per  kg.  by  vein  at  once. 
12.02  a.m.  Emesis.    (Repeated  emesis.) 
4/ii/'io.    Cat  weighs  1.68  kgs.,  having  lost  0.34  kg.  in  weight. 
9.42  a.m.  Injected  0.075  Gm.  digitalis  per  kg.  by  vein  at  once. 
9.58  A.M.  Death  occurred.  (Cumulation.) 
We  have  tested  the  following  substances  by  intravenous  injection 
into  the  cat :  Crystalline  ouabain,  amorphous  strophanthin,  strophan- 
thus  seed,  tincture  of  strophanthus,  digitalis,  tincture  of  digitalis, 
infusion  of  digitalis,  digitoxin,  digitalinum  verum,  digitalein,  adon- 
idin,  digalen,  amorphous  digitoxin  so-called,  digipuratum,  all  be- 
longing to  the  digitalis  group,  and  German  digitalin  which  does  act 
