610 



ELECTKICAL STIMULATION OF THE FROG'S HEART. 



temperature for a considerable time before the experiment. The 

 tracing obtained at room temperature (K^ Fig. 202) is therefore 

 that of a cold heart, and the refractory period extends up to the 

 commencement of relaxation after systole. After hot water 

 had been run through the support for 5', and the temperature 

 raised about 2° C, we find diastole increased and systole much 

 shortened; at the same time there is a refractory period as 

 extensive as in the cold heart, that is to say, extending to the 

 commencement of relaxation K„. 



Stimulation of Yentricle (maximal stimulation). 



Xi. Heart at room temperature, frog long kept in cold room. 



Ka- Temperature raised 2° C. 



Ko. Taken 10' later than Kj, during \?hicli time temperature was raised 1° C 



X4. Temperature raised again 1* C. 



Xs. Temperature raised 1° C, making about 5° C. altogether abore Ki. 



