HEATED HEART-STIMULATION OF VENTRICLE. 

 Fig. 203. 



611 



Drum of more rapid rotation used in tracings given m Appendix B. The 

 electro-mai'net marks seconds. 



In Kg after heat had been applied 10', and the temperature 

 raised another degree, stimulation at an earlier phase produces 

 reduplication. Heated still further, K^, there is reduplication 

 at systolic maximum, and at Kg everywhere except at the very 

 commencement of systole. After heating through about 5° we 

 still have a refractory period, whilst the curve has been reduced 

 from 1"4 to 0-4". In many cases, however, the same amount 

 of heat may obliterate the refractory period completely. The 

 heart which yielded these curves passed into rigor without 

 showing the abolition. In the heated heart, of which the ven- 

 tricle is stimulated, we may find that the auricle does not in 

 any way participate in the ventricular excitement, but con- 

 tinues tu beat in its usual rhythm. Thus when the heated 

 heart yields a series of contractions in answer to a single stimu- 

 lation — a result not unfrequently obtained — the auricle does 

 not reduplicate, but may give its systole in due place, whilst 

 the ventricular contractions are still occurring. "Not only is 

 this indifference to ventricular action observed on the part of 

 the aur' 4e, but the counterpart may be occasionally seen in the 

 ventricle, faiUng to fullow the normal systole of the auricle L 

 (Fig. 204). This is in part due to the fact that the auricle has 

 only shared imperfectly in the heating. 



Stimulation of Ventricle (maximal). Heart heated about Y° C. Time as in K. 



2 R 2 



