STRYCHNIA-STIMULATION OF AURICLE AND SINUS. 617 



At the maximum of auricular systole, Fig. 211 R^, we have an 

 immediate auricular response, and a ventricular latency of 0*4''; 

 and in Fig. 211 (E..) there is an almost instantaneous ventricular 

 systole, with an auricular latency of about 15''. The diastolic 

 pause is the longer the later stimulation falls. In Fig. 211 lii 

 it is 0-9" ; in Fig. 211 R^ it is l''-9 ; in Fig. 211 Eg it is 2"-:5. 



Stimulation falling just after maximum of auricular systole, 

 and at the commencement of ventricular systole, may cause in 

 addition to the results enumerated, omission of the succeeding 

 auricular and ventricular contractions, or reduplication of the 

 auricular, but omission of the succeeding ventricular (Fig. 212 S). 



Stimulation of Auricle (maximal). Levera as in Fig. Q.. 



Thus the induced auricular contraction in this instance, 

 instead of passing a motor impulse downwards to the ventricle, 

 appears not only to check the reduplication, but greatly to 

 prolong the diastole. 



It is easily recognised from the auricular tracing that the 

 induced contraction is one of the unfilled cavities (Fig. 212 S), 

 but though little or no blood passes into the ventricle, a positive 

 effect upon the latter is still produced. 



Venous Sinus. 



As regards the relationship of the auricular reduplication to 

 the time of stimulation, we find the latency of the auricle occa- 

 sionally varying in length, but usually it has very nearly equal 

 values, except when the shock, falling during ventricular re- 

 laxation, calls forth a simultaneous auricular and ventricular 



