WALTER E. GARREY 



43 



15 and 25 °C. respectively, has rates giving an average temperature 

 coefficient (Qio) equal to 2.23. This indicates that the rate is deter- 

 mined by the alteration of a chemical process. The coefficient is 

 quite in conformity with that reported for other rhythmic biological 

 processes for this range of temperature. 



TABLE I. 



In order to obtain a more comprehensive conception of the varia- 

 tion in the temperature coefficient of the whole heart subjected to 

 different temperatures, summaries of some experiments are given 

 below. The first shows the effect of cooling the heart to — 2°C. and 

 then progressively warming in a single but typical experiment. 



The progressive change from a large coefficient at low temperatures 

 to the smaller values at high temperatures is not always as uniform 



