302 T. Brailsford Robertson: 



resumed ; although occasional convulsive mo vements occur, these 

 become less and less frequent and respirations continue except 

 during the actual convulsions. The rate of the respirations is, 

 however, unaltered for the first six minutes; in from 10 to 

 12 minutes they may be accelerated 10 per cent but not more. 

 Now the time which elapses before the respirations are quickened 

 is only 1 to 2 minutes when the aeid is applied directly to 

 the medulla and the animal usually does not struggle at all. 

 Moreover the two effects, the efifect upon the respiratory eentre 

 and that upon nerve-fibres, can readily be distinguished frora 

 one another in the case of ^/^^ oxaU aeid. At first the normal 

 effect of an aeid upon respiration is observed, namely a marked 

 quickening of the rhythm so that after 10 minute the rate may 

 be doubled. If further applications of oxalic aeid be made, 

 the rate continues to increase until over one half hour after 

 the first application of oxalic aeid when the muscles of the 

 whole animal go into prolonged tetanic contractions ; the former 

 effect is that of the aeid upon the respiratory eentre, the latter 

 effect is that of the oxalic aeid anion upon nerve-fibres. 



In reviewing the above results we are led to suspect that 

 the processes which occur in nerve-cells as a result of their 

 Stimulation are of the nature of oxidations, since they are 

 accelerated by oxidising agents and slowed by reducing agents, 

 confirmation of this idea is afforded by the action of KCN in 

 slowing or even altogether inhibiting the activity of the 

 nerve-cells, since KCN is known to inhibit oxidations in Hving 

 organisms.^) 



One fact, however, Stands out perfectly clearly and that is that 

 acids accelerate the processes underlying the activity of nerve- 

 cells, while, at the same time, these processes lead to the 

 setting free in the nerve cells of a substance or substances of 

 an aeid nature. The processes underlying the activity 

 of nerve-cells are therefore of the nature of autoca- 

 talysed chemical reactions in which one of the products 

 of the reaction is the catalysor, and, probably, are 

 autooxidations. 



^) Sohönbein, Quoted after Loeb, „Dynamics of Living Matter", 

 New York 1906, S. 27. — Geppert, Zeitschr. f. klin. Med. 1.5, 208 und 307. 

 — Budgett, Amer. Joum. of Physiol. 1, 210, 1898. 



