210 SECONDARY ELECTROMOTIVE PHENOMENA IN 



and there was no longer any difference between ascending- and 

 descending polarisation. After fifty-five and a-half hours there 

 was still a trace of negative polarisation to be seen amounting to 

 about one degree of the scale. When the negative polarisation 

 alone remains, it is the same in both directions in the sensory 

 roots. Consequently the difference which living roots exhibit with 

 regard to polarisation by the ascending and descending currents, is 

 to be attributed to positive polarisation ; in both kinds of fibres, 

 though less markedly in the motor fibres, the negative polarisa- 

 tion is as strong and the positive not weaker in the direction of 

 the physiological wave of innervation than in the opposite direction. 

 The question referred to in Sect. 10 has thus been decided as regards 

 nerves as was anticipated, and the method I chose of representing 

 it is justified. 



Without having made the experiment on the two halves of the 

 muscle, I do not doubt that it would yield a similar confirmation. 

 We shall meet with another fact pointing in the same direction 

 further on. 



It would be interesting to make polarisation experiments with a 

 bundle of nerve fibres without perineurium, such as one gets in 

 the manner described by Harless l . 



19. Positive internal Polarisation in Nerves in conflict with 



Tetanus. 



The idea suggested itself of transferring the experiment de- 

 scribed in Sect. 12 as made on muscles to nerves, and to examine 

 what influence the state of activity of nerves would have on their 

 internal positive polarisation. Although this plan of research has 

 been among my agenda since 1857, I have not succeeded in carry- 

 ing it out. In the meantime another fact became known from a 

 different source, which did not indeed directly answer the question 

 here stated, but which made it possible to foresee the answer with 

 some certainty. This was the fact discovered by Griinhagen, that the 

 strength of a current passed through a nerve increases on tetanising 

 the nerve. Griinhagen explains this increase by diminution of 



1 Moleculare Vorgange in der Nervensubstanz, ii. Abhandlung, Voruntersuch- 

 ungen. Aus den Abhandlungen der K. bayer. Akademie, vol. viii. part ii. 

 Munchen, 1858, p. 538 ff.; cf. Charles E. Morgan, Archiv fur Anatomic, Phy- 

 siologic, etc. 1863, p. 340; Electro-Physiology and Therapeutics, etc., New York, 

 1868, p. 464. 



