NOEMAL HEART-STIMULATION" OF AURICLE. 5«5 



Istly. Stimulation may fall at such a stage of auricular 

 activity that it does not cause an instantaneous response, but 

 allows the auricle to pass through its diastole before it causes 

 reduplication. 



2ndly. It falls at such a time that the auricle responds in- 

 stantaneously. 



3rdly. About or shortly after the period of auricular maxi- 

 mum stimulation may cause inhibition of the auricular and the 

 ventricular sequential beat. 



Stimulation at any period during the diastole of the auricle 

 until the abscissa is reached, causes a reduplication. The latency 

 of this reduplicated beat is shorter the further the diastole is 

 advanced. It is followed by an induced ventricular beat in 

 ordinary rhythm. 



Stimulation during complete auricular diastole and before 

 systole commences causes a contraction with very short latency, 

 succeeded by an induced ventricular contraction. But it is to 

 be noted that occasionally stimulation at this period causes a 

 normal auricular contraction with an appreciable latency, and 

 followed by a ventricular contraction. 



Stimulation of the Auricle — Maximal. 



Maximal stimulation of the auricle almost always produces 

 some effect both on the ventricular and auricular beat; this 

 effect is usually one of stimulation, but it may be of apparent 

 inhibition. 



Fig. 172. 



Stimulation of Auricle (maximal). 



