DYNAMICS OF NERVE CELLS. 



II. The Temperature Coefficients of Carbon Dioxide Produc- 

 tion BY THE Heart Ganglion of Limulus polyphemus.* 



By WALTER E. GARREY. 



{From the Physiological Laboratory of the Tulane University Medical School, New 



Orleans) 



(Received for publication, July 24, 1920.) 



That the rate of the heart beat of Limulus polyphemus is deter- 

 mined by the rate of chemical reactions within the nerve cells of the 

 cardiac ganglion is shown by the magnitude of the temperature coef- 

 ficient (Qio) as determined by the author.^ The differences in the 

 temperature coefficient, the form of the rate curve, and the effects of 

 extremes of temperature suggested the probabihty that the velocity 

 of the chemical reaction was modified by a consecutive physical pro- 

 cess with a different temperature coefficient. The formation of 

 CO2 in the nerve cells and its diffusion from them are suggested as 

 processes analogous to those underlying the determination of the 

 rate of impulse formation. 



The following report shows that changes in temperature affect car- 

 bon dioxide formation by the ganglion cells in a manner which is 

 quantitatively similar to the effect on the rate of the rhythmic con- 

 tractions, thus establishing a basis for a hypothetical explanation to 

 account for the different magnitude of the temperature coefficient at 

 different ranges of temperature, and also for the change in the rate 

 curve as affected by extremes of heat and cold. 



* The experimental work was done at the Marine Biological Laboratory, 

 Woods Hole, Massachusetts. The author wishes to express his appreciation of 

 the courtesy of the Director and staff of the Laboratory for placing the facilities 

 for this work at his disposal. 



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



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