Am"Mayri9Pi3?rm'}       Keeping  Properties  of  Digitalis.  209 
as  being  entirely  worthless  except  as  specimens.  The  fallacy  of 
this  view  is  obvious,  for  each  was,  found  to  have  an  activity  about 
equal  to  that  of  the  average  fresh  specimen  of  good  quality.  By 
the  cat  method  the  average  unit  for  digitalis,  in  terms  of  leaf,  is 
100  mg.  per  kilo  of  cat  weight;  the  range  of  variation  in  activity 
of  different  fresh  specimens  of  good  quality  runs  from  75  mg., 
for  the  most  active  samples,  to*  120  mg.  for  the  less  active.  Since 
these  two  showed  no  deterioration  we  then  examined  the  oldest 
specimen  of  leaf  which  we  had  obtained. 
This  was  a  sample  of  about  12  gm.  of  whole  dried  lealf  which 
had  been  kept  in  a  glass-stoppered  bottle  for  not  less  than  twenty- 
five  years.  The  entire  specimen  was  powdered  and  passed  through 
a  No.  60  sieve.  After  thorough  mixing,  10  gm.  of  this  powder  were 
extracted  as  follows:  The  powder  was  moistened  with  4.0  c.c.  of 
dilute  alcohol  (U.  S.  P.)  and  allowed  to  stand  for  twenty-four 
hours  in  a  cylindrical  percolator ;  it  was  then  packed  tightly  and  per- 
colation was  started;  this  was  allowed  to  continue  until  about  30.0 
c.c.  were  obtained ;  percolation  was  then  interrupted,  maceration 
continuing  until  the  following  day,  when  percolation  was  again 
allowed  to  proceed  until  100.0  c.c.  had  been  obtained. 
Three  tests  by  the  cat  method  gave  the  following  units :  74 
mg.,  95  mg.,  and  82  mg.,  an  average  cat  unit  of  87  mg.  per  kilo. 
Perfectly  fresh  samples  of  the  most  active  leaf  which  we  have 
been  able  to  procure  have  not  shown  a  lower  cat  unit  than  65  mg. 
per  kilo.  This  twenty-five  year  old  leaf  was,  therefore,  of  very 
high  activity,  better  even  than  the  average  fresh  specimen.  The  leaf 
was  very  dry  and,  although  we  did  not  determine  its  moisture 
content,  we  may  assume,  according  to  the  statements  of  Focke,1  that 
it  contained  much  more  than  his  required  minimum  of  1.5  per 
cent.,  especially  as  the  specimen  had  not  been  preserved  with  any 
particular  care.  This  specimen,  therefore,  had  almost  certainly 
undergone  no  deterioration  during  twenty-five  years  of  standing. 
The  cat  has  been  said,  incorrectly  we  believe,9  to  be  unsuitable 
for  the  detection  of  deterioration  owing  to  the  toxic  nature  of  the 
products  of  such  deterioration,  but  none  of  our  cats  showed  atypical 
effects. 
We  also  examined  this  specimen  by  the  one  hour  frog  method, 
and  found  the  fatal  dose  to  lie  between  900  and  1000  milligrams 
9Amer.  Jour.  Pharm.,  lxxxv,  1913,  p.  99. 
