Kosfîarclu's on the Dischar"-c of the Electric Orjxan. 



'J.i 



his foi-mula irom tlic liypotlicsis of Neriist, but liis solution of tlie 

 (liffercntial equation does not satisfy the initial condition of uniform 

 concentration. The main «lefects of In's formula are: (1) 

 the definition, explaining how the excitation in a nerve is 

 measured, is very obscure; (2) since his formula is deduced from 

 the exj)erinîental data at a point of minimal excitation, it is not 

 possilde to extend it into the region of finite excitation. 



In 1010 Hill,''^ following Nernst's hyj)othcsis and introdu- 

 cing the assumption of Lapicque, found excitation formulae in 

 several cases of electric stimuli. Since his consideration is based 

 on the theory of " all or none " first pi-oposcd l)v (Jotch, the 

 formulae have a somewhat different meaning from that of 

 Hoorweg. 'i'hey i-epresent the progression of a local change which 

 on attaining a definite value causes an actual excitation. At 

 anj'rate, in the case of a constant current, his formula contains the 

 exponential function as the term that varies with the duration of 

 stimulating current. According to the *' all or none '' theory the 

 magnitude of the response depends on the number of elementary 

 portions that receive a stimulus greater than the threshold 

 value to evoke the response. The number may depend on the 

 distribution of tlie current in a tissue or on the variety of the 

 elementary portions whose minimal stimuli are difïei'ent h-om one 

 another. In the former case, the relation between the electric 

 stimulus and its response reduces to a mere ])hysical probk-m. 

 and as in the latter case to that of some kind of probability. 



Since it was considered that the discharge of an electric organ is 

 the best means for the investigation of such j)i'oblems, many experi- 

 mentsin these subjects were made. Let us here explain the superiori- 

 ty of the discharge as a means for the investigation of the genei'al 

 properties of excitation in tissues. The means ordinarily used are 

 muscular contraction and negative variation in a nerve or in a 

 muscle. In the former case very trouljlesome factoi-s of elasticity and 

 viscosity (if the latter term may be allowed) in a muscle complicate 

 the phenomena. On the contrary, the negative variation is an 

 ideal means for the purpose, but to obtain its record w^e are obliged 



* The Journal of Phy.siolo<jy, V^ol. 40, p. 101, 1910. 



