COOLED HEART AND HEATED HEART. 



609 



Ij to la. Levers us m A. fcJtiumlation of Venous Sinus (maximal). 

 Fig. 201. 



Time tracing. Electro-magnet recording seconds, 

 in Appendix A. 



Applicable to all tracicga 



Appendix B. Heated Heart. 



In some cases, heating a frog's heart through 4°'5 C. may fail 

 to obhterate entirely the period of resistance to stimulation. 

 Heat, however, in the same experiment may be shown to shorten 

 the refractory period much, and to limit it to the very com- 

 mencement of ventricular systole (in stimulation applied to the 

 ventricle). The series of tracings given were taken from a large 

 specimen of Bana escidenta, which had been kept at a low 



2 R 



