Tracing    i-A.    From   a  nor-      Tracing   i-B.    From   a   frog's  heart  shortly 
mally  beating  frog's  heart.  after  the  appHcation  of  adonis;  showing  a 
sHghtly  slower  rate  of  beat. 
dilatation  shown  shortly  after  the  appUcation  of  the  drug;  this  is 
always  immediately  followed  by  a  lessened  dilatation,  as  the  lever 
rises  higher  and  higher  each  succeeding  diastole.  Since  the  systolic 
contraction  cannot  raise  the  lever  higher  even  by  its  increased 
Tracing  i-C.     The  same  tracing  later. 
strength,  the  excursions  become  gradually  smaller  until  the  heart 
finally  stops.  Records  of  the  heart  taken  in  this  manner  frequently 
show  a  one  to  two  rhythm  between  the  auricles  and  the  ventricles  in 
the  latter  stages  of  poisoning  (see  tracing  i-I>);  this  indicates 
that  adonis  decreases  the  power  of  conduction  between  the  auricles 
and  the  ventricles,  in  the  same  manner  as  does  digitalis.  The  trac- 
ings I -A,  B,  C,  are  very  typical  of  the  effect  of  adonis  upon  the 
heart's  rate  of  beat.  The  heart  is  always  slowed  until  it  reaches  the 
toxic  stage  when  it  becomes  rapid  and  irregular.  When  the  frogs 
heart  has  been  stopped  by  adonis,  it  presents  a  very  characteristic 
picture,  namely,  that  the  ventricular  walls  are  firmly  Contracted 
so  that  they  appear  quite  pale  in  color,  the  auricles  being  widely 
