ADVANCED EXPERIMENTAL PHYSIOLOGY 347 



The result of warming the sinus is a great increase in the rapidity 

 of the beats both of the auricle and ventricle. 



FIG. 227. Record of the contraction of the toad's heart by the suspension method. 

 Heat applied by the copper wire method. The signal in the third Hue shows the 

 period during which the sinus was heated. Acceleration of the whole heart was pro- 

 duced. In this curve the down-stroke represents the contraction. The time is 

 marked in seconds. (L.H.) 



FIG. 228.- Continuation of Fig. 227. Ventricle heated. Augmentation of the 

 ventricular contraction, but no change in frequency. (L. H.) 



Now warm the ventricle in like manner. No alteration of rate of 



