AmM£Sh,iM&DD"}      Standardization  of  Preparations.  115 
Moreover,  it  has  been  shown  not  only  that  moist  leaves  quickly  be. 
come  worthless,  and  that  only  the  dried,  or  almost  completely  dried, 
leaves  can  be  kept  for  any  appreciable  length  of  time  without  de- 
terioration, but  that  great  care  must  be  exercised  in  the  process  of 
drying,  in  order  that  the  very  process  which  is  intended  to  aid  in 
preserving  the  activity  of  the  leaves  be  not  instrumental  in  destroy- 
ing it.  (In  Caeser  and  Loretz's  report  in  the  Apotheker  Zeitung, 
1907,  p.  794,  Dr.  C.  Focke  is  quoted  as  stating  that  to  dry  leaves 
until  1-5  per  cent,  moisture  remains  is  a  guarantee  against  deterior- 
ation. It  is  probable  that  this  only  means  that  when  all  but  1-5 
per  cent,  of  moisture  has  been  removed,  enough  has  been  eliminated 
to  guard  against  deterioration  due  to  the  hydrolyzing  effect  of  the 
moisture,  whereas,  on  the  other  hand,  the  drying  has  not  been  pro- 
longed so  far  as  to  injure  the  delicate  active  principles. 
It  is  perfectly  apparent,  therefore,  that  the  appearance  of  the  drug 
per  se  can  be  no  criterion  of  its  activity.  The  National  Standard 
Dispensatory  (page  530)  states  that  there  is  no  satisfactory  method 
of  distinguishing  leaves  of  the  first  from  those  of  the  second  year's 
growth.  Moreover,  the  process  of  drying  would  serve  further  to 
render  more  difficult  a  macro-  or  microscopic  distinction  between 
active  and  inactive  leaves,  and  the  same  sample  of  leaves,  although 
originally  good,  but  improperly  dried,  would  be  difficult  to  distin- 
guish from  the  same  lot  when  dried  under  proper  restrictions  as  to 
heat  and  light.  It  has  been  my  experience  in  examining  samples 
of  digitalis  leaves  for  several  years,  that  physical  appearance  is  not 
a  reliable  criterion  of  quality,  although  the  identity  of  the  leaf  can 
be  established  with  comparative  ease. 
No  one  will  deny,  therefore,  that  some  sort  of  standardization  of 
digitalis  leaves  is  not  only  highly  desirable,  but  is  indispensable  to 
the  putting,  of  uniformly  reliable  preparations  into  the  hands  of 
physicians.  Tested  leaves  only  should  be  used  for  the  preparation 
of  infusion  of  digitalis  to  be  used  extemporaneously,  and  all  prep- 
arations of  digitalis  intended  to  be  kept  for  some  time,  such  as  the 
tincture  and  fluidextract,  should  themselves  be  subjected  to  some 
method  of  testing  whereby  not  only  proof  of  their  activity,  but  its 
degree  as  well  may  be  established.  It  is  well  recognized  that  the 
fact  that  tinctures  and  fluidextracts  have  been  prepared  from  assayed 
drugs  is  not  in  itself  a  guarantee  of  uniformity. 
The  physiological  action  of  digitalis  is  primarily  that  of  a  cardiac 
