WALTER E. GARREY 



55 



That the cardiac ganglia of different Limuli should show individual 

 differences in the rate of carbon dioxide development is not surprising 

 but the physiological significance of the metabolic variations is not 

 so apparent. In our first paper^ attention was directed to the fact 

 that there were marked individual variations in the rate of the car- 

 diac rhythm of different Limtili but that all showed temperature co- 

 efficients indicating the chemical character of the causative reaction. 

 The present investigation was undertaken to determine whether car- 

 bon dioxide development was affected by temperature like the heart 

 rate, and while it has been demonstrated that this is the case it has yet 

 to be shown that, given two ganglia of equal weight but with different 

 heart rates, the rate of carbon dioxide development is proportional 



TABLE III. 

 Relation of Cardiac Rale to Development of CO2. 



to the rate of the rhythm. To settle this point two Limuli of the same 

 size were selected which showed heart rates of 8 and 16 per minute 

 respectively at room temperature (22°C.). The hearts were excised 

 and the rate of each at 12° was determined, after which the ganglia 

 were dissected from the hearts and the rate of carbon dioxide develop- 

 ment was then determined. The results, compared with the previous 

 rates, are given in Table III. 



The results of this experiment (Table III) leave no doubt that the 

 rate of COo development by the ganglia and the rate of cardiac rhythm 

 run parallel courses. 



All the experimental results herein reported thus show that the 

 temperature coefficients of carbon dioxide production by the ganglia 

 are of a magnitude entirely commensurate with those previously re- 



