"^"oct^rer;  im™'}        ^J^ethod  for  TTesting  Digitalis,  Etc,  489 
injected  at  a  more  rapid  rate  possibly  less  onaljain  may  have  been 
used  than  would  have  been  under  normal  conditions. 
It  might  be  remarked  that  the  first  experiment  would  furnish 
these  points.  This  might  be  true,  still,  it  might  happen  that  the 
results  from  number  one  would  be  exceptional.  Then  the  operator 
would  be  thrown  off  on  number  two,  and  when  he  found  the  results 
from  number  two  quite  difi;erent,  number  three  would  be  necessary 
in  order  to  tell  which  was  more  nearly  correct. 
If  these  points  are  of  no  importance  then  it  would  seem  that 
the  time  limit  of  ninety  minutes  would  be  of  no  importance. 
Number  of  Animals  and  Time. — In  general  it  would  seem  that 
at  least  three  experiments  w^ould  be  necessary  in  order  to  determine 
with  confidence  the  strength  of  a  preparation.  If  two  out  of  three 
results  checked  quite  closely,  as  under  F.  E.  Digitalis  No.  405467 
(.113,5,  .115,2),  that  number  might  be  sufficient.  Under  strophan- 
thus  seed  No.  B-565,  however,  the  results  show  a  gradual  increase 
up  to  the  sixth  experiment  (.001,19,  .001,37,  .001,53,  .001,66, 
.001,88),  and  under  F.  E.  Digitalis  No.  416233,  results  Nos.  i,  4, 
and  6  check  each  other  rather  closely  (.077,3,  -086,1,  .087,4),  and 
Nos.  2,  3,  and  5  at  a  different  figure  check  each  other  even  more 
closely  (.065,8,  .068,2,  .068,8). 
If  three  or  four  experiments  were  sufficient,  then  an  assay  could 
be  made  in  one  day,  a  point  in  favor  of  the  method.  This  would 
require  one  person's  entire  time  and  attention  for  the  four  and  a 
half  or  six  hours,  besides  part  of  the  time  of  an  assistant.  At 
that,  more  actual  time  would  be  required  than  for  any  of  the  other 
methods. 
Ease  of  Mwiipulation  and  Accuracy. — The  method  seems  simple, 
and  still,  all  points  considered,  it  is  the  most  difficult  of  all  with 
which  I  am  acquainted. 
My  results  have  been  quite  disappointing.  They  show  variations 
for  the  different  preparations,  as  follows : 
Ouabain    123.3  per  cent. 
Excluding  results  Nos.  2,  4,  8,  and  25   61.4  per  cent. 
Strophanthus  Seed  No.  B-565   57-9  per  cent. 
Strophanthus  Seed  No.  B-566   48-3  per  cent. 
F.  E.  Digitalis  No.  4054^7   19.0  per  cent. 
F.  E.  Digitalis  No.  416233   32.8  per  cent. 
F.  E.  Digitalis  No.  335929  (excluding  lactating  animals)   90.5  per  cent. 
Excluding  lactating  animals  and  No.  i   53-0  per  cent. 
Tr.  Digitalis  No.  2-B  (excluding  Nos.  3  and  5)   67.8  per  cent. 
