464 



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



usually causes omission of the following sequential beat of both auricle 

 and ventricle. 



This period may occasionally be slightly prolonged into systole. 



Stimulation of the sinus at all other periods of ventricular activity 

 causes a reduplication of the systole. This induced ventricular systole 

 is preceded by an induced auricular systole, and therefore has the 

 prolonged latency before referred to. 



Stimulation falling at the commencement of ventricular systole may 

 cause auricular reduplication with ventricular omission (fig. 7, a). 



In consequence of the long latency, we find all ventricular curves 

 separated by a distinct interval from (their) reduplications. 



Stimulation of Venous Sinus — Maximal. 



The period during which stimulation causes ventricular omission is 

 well marked, and in some cases extends into the ventricular systole as 

 it advances towards its maximum, though the effect is never produced 

 at the maximum. 



This omission of ventricular beat is most usually associated with a 

 reduplication of the auricular beat, the second auricular contraction 

 occurring within that ventricular systole at the commencement of 

 which the shock was communicated (fig. 8, b). 



Stimulation of Yenous Sinus (maximal), a, normal rhythm j b and c, stimulations 



all effective. 



Reduplication occurs in all phases except at the period when stimu- 

 lation causes omission. The latent period of this reduplication is 

 usually short, as in the case of a ventricle stimulated directly, 

 inasmuch as the induced auricular contraction does not precede the 



