THE RESPIRATORY RATE OF THE SCIATIC NERVE OF 

 THE FROG IN REST AND ACTIVITY. 



By a. R. MOORE. 



(From the Physiological Laboratory of Rutgers College, New Brunswick, N. J.) 



(Received for publication, May 22, 1919.) 



It has been accepted generally that nerve fibers have extremely low 

 metabolic activity and that their oxidation processes in no way in- 

 crease as the result of excitation. Such conclusions are based on the 

 facts that (1) tetanization does not increase heat production in 

 the nerve,^ and (2) the nerve cannot be fatigued by stimulation. 

 Furthermore, the well known fact that the nerve trunks are poorly 

 supplied with blood vessels weighs against any assumption of the 

 dependence of physiological function upon a high degree of metabolic 

 activity. 



On the other hand, it has been shown by Waller^ that the intensity 

 of the reponse of nerve fibers to excitation is increased by the appli- 

 cation of carbon dioxide, and that nerves show the staircase phe- 

 nomenon when tetanized. From this the conclusion has been drawn 

 that carbon dioxide is produced by the nerve itself as a result of 

 activity, and that this carbon dioxide acts further to increase the 

 sensitivity of the tissue, thus resulting in the staircase effect. It 

 should be pointed out that there are many substances which increase 

 the sensitivity of nerve fiber, for example, salts like the sulfates, 

 oxalates, or citrates. In fact Waller does not insist on the fact 

 of carbon dioxide production by nerve, but says that the staircase 

 effect may be due to some other substances.^ 



Recently, Tashiro^ attempted directly to estimate the amount 

 of carbon dioxide given off by the excised nerves of frogs and crabs. 



1 HiU, A. v., /. Physiol., 1911-12, xliii, 433. 



2 WaUer, A. D., Proc. Roy. Soc. London, 1895-96, lix, 308. 



^ Waller, A. D., Physiology, the servant of medicine, London, 1910, 43. 

 * Tashiro, S., A chemical sign of life, Chicago, 1917. 



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