( 75 ) 



preparation, will cause in it an irritalion-elfect that is at any moment 

 proportional to the intensity of' the current at that moment, but that 

 likewise, according to the term c.-r-t- regularly decreases in the course 

 of time, aud can thus be represented by the curve .l^z/^cr/, which first 

 increases and al'terwards rapidly decreases and sinks down to the 

 axis. The total irritation-elFect is now represented by the area of the 

 figure enclosed between the curve Aahcd and the horizontal axis. 

 For a minimal contraction a definite area is recpdred. As a rule 

 this is part of the whole area, e.g. tlie piece A<iJ)fA, but if the 

 current applied is weak, it may be that the whole area Aahcd 

 is not sufficient. The sauie will likewise take j)lacc, though the current 

 is very strong, if the ascent is very slow e.g. aloug the line AB' in- 

 stead of along the line AB, for then the perception-curve Aa^y, 

 descends a long tiuie before the current has obtained its constant 

 valne, to zero, and the irritating area is too small. 



For alternate currents formula (5) gives an irritation-effect, which 

 with the number of alternations first increases and then decreases again, 

 consequently the formula points to an optima frequention to which 

 the organ is most sensible. This optima frequention now has been 

 distinctly fonnd by d'Arsonval (14), Prevost and Batelli (15), v. Kries 

 (16), WiEN (17) and others. Moreover Wertheim Salomonson (18) 

 found for very high alternations results corresponding to my formula. 



4. After all these results I hoped to have founded on a solid base 

 the study of the irritation-process. And that was the object of my 

 investigation. But 1 know very well that both formula (5) and 

 formula (1) were afterall oidy empirical formulas. An explanation, 

 why all organisms were subject to that rule, was not given. Conse- 

 quently a reasonable question remained to be solved : how is the 

 irritation-effect pi'oduced? 



In 1899 Nernst, the celebrated physico-chemist of Berlin, gave an 

 answer to this question in a treatise in which he says: "Every organic 

 tissue contains electrolites, and in electrolites nothing else can occur 

 than motion of ions. This motion of ions must consequently be the 

 cause of the irritation-effect." 



These bold words pronounced by a man of authority made every- 

 where a deep impression. 



Nernst however was in the beginning only able to work this 

 theory out for alternate currents and when doing so came to a formula 

 deviating so widely from the ordinary one, that many investigators 

 and myself likewise considered this attempt to be a failure. But on the 

 ground of new experiments of Barratt (20) and Reiss (21 j Nernst 

 in 1908 reverted to the subject again, and defended in a detailed 



