458 



Drs. T. L. Bruuton and T. Cash. 



(4.) Where acceleration or reduplication occurs, the subsequent 

 diastolic pause is prolonged, so that the time occupied by the two 

 beats, the interval between them longer or shorter, and the subse- 

 quent pause, is nearly equal to the time which would be occupied by 

 two normal beats with their associated diastolic pauses (fig. 1, c). 



(5.) The ventricular reduplication is often associated with a 

 reduplication of the auricular beat, but in no case has the latter its 

 commencement before the former. It is usually, in fact, distinctly 

 later (fig. 2, a). 



It is to be noted that, minimal stimulation applied to the ventricle 

 during its refractory period produces no effect on the auricle. 



Fig. 2. 



a. 



Stimulation of Ventricle (minimal). Tracing shows long pause after reduplication. 

 The two opening stimulations occur after maximum of systole has passed. 



Time-Writer, marking seconds. Applicable to all tracings in the paper, except those 



in the Appendices. 



We may divide each ventricular cycle into three parts, the first 

 reaching from the commencement of systole nearly up to its 

 maximum, the second from nearly the maximum of the systole to its 

 end, and the third embracing the whole diastolic period from the end 

 of one systole to the beginning of another (vide diagram A) except 



A. 



Diagram A shows the division of the ventricular cycle into three parts. — 

 1. Refractory period. 2. Sensitive period. 3. Accelerative period. 



when the stimulation falls immediately after the end of the refractory 

 period. In all these points our results agree with those already 

 obtained by Marey.* 



* Op. citat., p. 72. 



