164 SECONDARY ELECTROMOTIVE PHENOMENA IN 



To these two long- known classes I added a third that of 

 secondary electromotive phenomena ; by which term I understand 

 those electromotive phenomena which an extraneous current pro- 

 duces in the portion of muscle it flows through, and which can gene- 

 rally only be observed owing- to their lasting long-er than the 

 extraneous current. These are the facts, to a great extent new, 

 about which I intend to treat. As I shall presently mention, 

 however, it will be found that a distinction can hardly be main- 

 tained between the two last classes. 



Secondary electromotive phenomena appear for the most part 

 as polarisation-currents. I prefer the former of these two expres- 

 sions, which is quite applicable to the ordinary phenomena of 

 polarisation, and could be used to designate the apparent polar- 

 isation of muscles and nerves, even though it should prove to be 

 different from galvanic polarisation. I do not, however, insist 

 pedantically on the name, but occasionally call the secondary 

 current, generated by the secondaiy electromotive force, the polarisa- 

 tion-current, and also the after-current ; while the primary current 

 which induces it is styled the polarising current. I also find it 

 sometimes convenient to speak of the body to be polarised as 

 * object of polarisation.' By negative I mean a polarisation-current 

 in an opposite direction to the primary current, and by positive 

 one in the same direction. 



2. Historical. 



At the commencement of my researches in science I encountered 

 a phenomenon which belongs to this subject. Peltier described in 

 1836 a negative polarisation in a frog's limb through which a 

 current was passing, which he compared to the polarisation of the 

 metals in Bitter's secondary battery. According to him the seat 

 of the polarisation was in the part of the limb immersed in the 



persistent passage of the current ; Eckhard unsuccessfully, Sachs with doubtful 

 results (Untersuchungen am Zitteraal u. s. w., p. 188 et seq.). Even if these experi- 

 ments had succeeded one could not speak of electrotonus of electrical organs. In 

 muscles Hermann thinks he has now found a trace of that electrotonus current which 

 formerly neither he nor I could prove, and which his theory so urgently required 

 (Handbuch der Physiologic, vol. ii. Leipzig, 1878, p. 1 68) Die Ergebnisse neuerer 

 Untersuchungen auf dem Gebiete der thierischen Elektricitat'. Separat-Abdruck 

 aus der Vierteljahrschrift der naturforschenden Gesellschaft in Zurich, 1878, pp. 21, 

 22. He does not consider the possibility that the observed action may proceed from 

 the intramuscular nerves. As early as in 1849 I warned against this fallacy (Unter- 

 suchungen, vol. ii. part i. p. 330). 



