460 



Drs. T. L. Brunton and T. Cash. 



A very considerable latency is to be observed in cases where 

 stimulation falls early in the systole. The latency, when this is the 

 position of the shock, is nsnally '5' or even more, and occasionally 

 where stimulation is coincident with the earliest possible attempt at 

 systole, nearly the whole beat may lapse before reduplication. 



The latency is greatest when the stimulus is applied at the com- 

 mencement of the ventricular systole (with the exception of its very 

 beginning), and it gradually decreases towards the end of systole, at 

 which time it is at a minimum. During the diastole the latency 

 seems to remain constantly the same as at the end of systole. The 

 later in the phase of ventricular activity the reduplicated systole 

 commences the more perfect is it. 



In all the points already mentioned our results agree with those of 

 Marey. 



Stimulation of the ventricle falling before or at the maximum of 

 ventricular systole, i.e., during the refractory period of a minimal 

 stimulation, frequently causes a reduplication of the auricular systole 

 which holds the same relation to the induced ventricular beat that the 

 auricular contraction normally holds to the ventricular. 



Fig. 3. 



c. 



Stimulation of Ventricle (maximal). 

 a, normal tracing ; b, effect of maximal stimulation. In b inhibition is seen. 



