On Electrical Stimulation of the Frog's Heart. 479 

 L\. 



D 1 to D 2 . Levers as in A. Auricular Stimulation (maximal) of Cooled Heart. 



Venous Sinus. 



In the heart which has been moderately or slightly cooled, 4 — 6°C. y 

 the occnrrence of ventricular reduplication without a precedent 

 auricular reduplication is very rare, even when strong stimulation is 

 employed. The refractory period occasionally observed may disappear 

 after a few stimulations have been given, or it may persist. Further- 



Ej to E 2 . Levers as in A, but no auricular tracing given. Stimulation of Yenous 

 Sinus. E b before cooling ; E 2 , after cooling. 



