THE RELATION OF RESPIRATION TO RHYTHM IN THE 

 CARDIAC GANGLION OF LIMULUS POLYPHEMUS.* 



By WALTER E. GARREY. 



{From the Physiological Laboratory, Tulane U?tiversity Medical School, New Orleans, 

 and the Marine Biological Laboratory, Woods Hole.) 



(Received for publication, September 19, 192L) 



A study of the carbon dioxide production by the cardiac ganglion 

 of Limulus polyphemus has shown a definite relation between the rate 

 at which the neurogenic heart beats and the intensity of the respira- 

 tion of the nerve cells which develop the rhythm. This has been dem- 

 onstrated by the parallelism between the temperature coefficient of 

 rate of heart beat and of CO2 production,^- 2 and also by the striking 

 diminution in the CO2 produced by the nerve cells when the inhibitory 

 nerve to the ganglion is stimulated — a fact which correlates the inhibi- 

 tory action of the ganglion with the respiratory processes of its nerve 

 cells. These facts at once suggest that automatic impulse formation 

 by the cardiac ganglion of Limulus, and probably by all automatic 

 nerve centers, may be determined by the velocity of those chemical 

 reactions in which carbon dioxide is produced by the nerve cells. 



The following report presents additional evidence in support of this 

 thesis and shows that a variety of agencies which stimulate the car- 

 diac ganglion and increase the rate of heart beat, produce a similar 

 increase in the rate of CO2 production by the nerve cells of the heart 

 ganglion. 



Method. 



The method was the same as that used in previous work.''^-^ The 

 color change of phenolsulfonephthalein was used to determine the 



* Funds granted by the American Association for the Advancement of Science 

 were used to meet the expenses of this investigation. 



1 Garrey, W. E., /. Gen. Physiol, 1920-21, iii, 41. 



* Garrey, W. E., J. Gen. Physiol, 1920-21, iii, 49. 



» Garrey, W. E., /. Gen. Physiol, 1920-21, iii, 163. 



149 



