Am"ju°yy'wo8arm'}      Notes  on  u  Physiological  Testing!'  333 
Ringer's  solution.  This  method  was  also  tried  by  Haynes.  The 
strength  of  these  solutions  is  judged  by  the  length  of  time  neces- 
sary to  cause  stoppage  of  the  right  ventricle.  Perhaps  some  of  the 
difficulties  with  such  experiments  are  due  to  the  fact  that  the  various 
principles  affect  different  portions  of  the  heart.  Focke's  method  of 
removing  the  sternum  in  unpithed  frogs  should  be  discarded  on 
humanitarian  grounds. 
Theoretically  to  me  the  proper  way  would  be  to  determine  the 
toxicity  of  these  preparations  on  guinea  pigs,  and  also  the  action  on 
the  isolated  mammalian  heart,  or  on  the  heart  in  situ,  noting  the  slow- 
ing of  the  heart-beat1  and  the  time  necessary  to  cause  stoppage,  and 
any  rise  of  blood-pressure,  or  by  making  use  of  the  physiological 
antagonism  between  digitalis  and  the  nitrites2  in  addition  to  the 
toxicity  experiments.  Naturally  in  such  experiments  the  depressing 
potassium  salts  should  be  removed  from  the  extract.  The  standard 
should  be  leaves  carefully  dried  in  vacuo  by  Wolff's  method  and 
then  protected  from  moisture  by  preserving  in  air-tight  vessels. 
It  is  needless  to  add  that  a  thorough  botanical  identification  of 
the  species  should  be  made  by  an  expert.  Other  species  of  digitalis 
besides  the  official  digitalis  purpurea  are  probably  also  active. 
It  must  be  confessed  that  the  methods  thus  far  proposed  are  not 
accurate.  A  long  series  of  experiments  should  be  made  with  one 
tincture,  and  checks  made  by  diluting  this  to  various  strengths  and 
comparing  the  results  obtained  from  these  known  dilutions  on 
animals. 
Dixon3  has  reported  that  if  5  c.c.  of  a  tincture  of  digitalis  be  placed 
in  the  stomach  of  an  anaesthetized  dog  and  the  stomach  be  exam- 
ined two  hours  later,  the  stomach  will  show  signs  of  acute  inflam- 
mation, and  Haynes  noted  that  after  similar  placing  of  tincture  of 
digitalis  no  effect  on  blood  pressure  was  observed.  This  failure  in 
action  was  probably  due  to  non-absorption.     Further,  Deucher4 
1  Fraenkel,  A.  Ueber  Digitaliswirkung  am  gesund.  Menschen.  Muench.  med. 
IVoch.,  Vol.  52,  p.  1537.  1905. 
2  Marshall,  C.  R.  On  the  Antagonistic  Action  of  Digitalis  and  the  Members 
of  the  Nitrite  Group.  Journ.  Physiol.,  Vol.  22,  1897-8. 
3  Dixon,  W.  E.     Manual  of  Pharmacology,  1906,  p.  169. 
4  Deucher,  P.  Ueber  d.  Wirkung  des  Digitalin  verum  bei  Circulations-stor- 
ungen.    Deutsch.  Archiv.  f.  klin.  Med.,  1896,  Vol.  57,  p.  34. 
NOTE. — In  considering  Strophanthus,  Hatcher's  article  in  the  Journal  of  the 
American  Medical  Association  for  1907,  and  Santesson's  article  in  the  Skan- 
dinavisches  Archiv  fuer  Physiologie  for  1905  may  be  serviceable. 
