156 



RELATION OF RESPIRATION TO RHYTHM 



have been introduced into Fig. 1 as solid characters. This striking 

 quantitative parallelism between rate of heart beat and rate of 

 development of CO2 in the cardiac ganglion, which is brought out 

 by this graph, forcefully substantiates the probability that the two 



35 



30 



(6 



Q— 

 O 



25 



20 



15 



S 10 



10' 



15' 



20° 25° 30° 35' 



40T.. 



Temperature 



Fig. 1. Curve of rate of heart beat when the ganglion is initially cooled from the 

 normal temperature to 0°C. (a), then progressively warmed to 38°C. (o),and 

 finally cooled to room temperature (□). The solid characters indicate the cor- 

 responding average rates of carbon dioxide production by the ganglion. 



physiological processes are bound together in the relationship of cause 

 and effect and that it is the velocity of those chemical reactions which 

 give rise to carbon dioxide formation in the cells of the cardiac gan- 

 glion which determines the rate of the neurogenic heart of Limulus 

 polyphemus. 



