A TEXTBOOK OF PHYSIOLOGY 



fcy then perfusing with a high concentration of potassium salts, sub- 

 sequently washed out by physiological saline. 



Potassium itself may restore the heart from a lactic acid diastole, 

 but not so completely as the combination of calcium and potassium. 

 The fact that the heart can be restored from diastole induced by 

 lactic acid by a high concentration of potassium, which is poisonous 



PIG. 65. ISOLATED RABBIT'S HEART PERFUSED WITH RINGER'S SOLUTION. (Dixon.) 



In I. ,0*2 per cent, potassium chloride added to the fluid. II. shows gradual recovery 



when KC1 withdrawn. 



to, and induces complete relaxation in, the normal heart, shows how 

 far we are from understanding the true part played by these ions in 

 relation to the automaticity of the heart. 



The Diastolic Filling of the Heart. In the excised heart no 

 evidence of any suction power has been observed; indeed, the heart 

 will only fill when supplied with blood under a positive pressure. 



