x ELECTROMOTIVE ACTION IN NERVE 335 



constant development of oxygen, along with its steady reduction 

 by the oxidisable groups of atoms of the excitable molecules. 

 " With weaker currents this process is not intensive enough to 

 liberate the intramolecular oxygen to any appreciable extent, 

 and thus transmit it as excitation. In principle, however, it is 

 co-significant with excitation, since there is a constant discharge 

 of potential energy. The molecule is thereby thrown into a state 

 of more labile equilibrium, since the freed oxygen slackens 

 its constitution, i.e. increases its excitability ; the intramolecular 

 oxygen is thereby more readily liberated by any stimulus." With 

 the exception of these special views in re the chemical process at 

 the kathode, and its localisation in definitely arranged and pre- 

 formed " molecules," Bering's theory conforms to that of Bernstein 

 in so far as both assume a constant discharge of energy, 

 or broadly speaking, in other words, a predominance of the 

 dissimilatory process over simultaneous assimilation throughout 

 the kathodic region ; i.e. both theories fall within the range of 

 the preceding experiments. 



Bernstein also has detailed views with regard to the processes 

 at the anode. " The positive ion liberated from the series of 

 molecules has, of course, opposite chemical properties to those of 

 the active oxygen at the kathode." Accordingly, there is no 

 excitation at closure of the current. Bernstein assumes, with 

 regard to the simultaneous depression of excitability, that " the 

 positive ion enters into molecular relations with the excitable 

 molecules of the fibre, and thereby renders the constitution of the 

 molecule more solid." We may thereby conceive " the positive ion 

 as an oxidisable component of the groups of atoms in the mole- 

 cule, the intramolecular oxygen being in consequence more 

 firmly linked with them as an electro-negative element." Here, 

 again, it is interesting to note the similarity of views between 

 Bernstein and Hering, as to the cause of the discharge of an 

 opening excitation. According to Pfliiger's theory as given 

 above, anelectrotonus is a state in which there is accumulation of 

 potential energy corresponding with the increased molecular 

 inhibition. This is interpreted by Bernstein to mean that " not 

 merelv is there a firmer combination of the intramolecular 



t/ 



oxygen, but that a greater quantity of it can be assimilated by 

 the molecule. Anelectrotonus therefore implies a -process of con- 

 stant assimilation, while the opposite process occurs in katclcctrotonus." 



