ADDENDUM. 



DURING the period which has been occupied in preparing the 

 foregoing- Memoirs for the press, the nature of the secondary 

 electromotive changes of nerve and muscle has continued to occupy 

 the attention of physiologists. In order to render this series 

 of memoirs more representative than it would otherwise be of the 

 actual state of knowledge, without delaying its publication, it 

 seems desirable to give a short account of one or two experimental 

 researches which have very recently appeared relating to a subject 

 dealt with in these memoirs. 



i. INTRAPOLAR POLARISATION OF NERVE. 



One of the questions to which the investigations of du Bois- 

 Beymond, Hering and Hermann, have given special interest is 

 that of the changes which take place in a nerve during the trans- 

 mission through it of a voltaic current in the tract which intervenes 

 between anode and cathode. Can it be demonstrated that an 

 electromotive force which did not before exist, comes into existence 

 in either direction in the intrapolar tract and, if so, what is its 

 relation to the intrapolar after effects observed in the various 

 modifications of Peltier's experiment ? 



The direct investigation of the intrapolar tract during the 

 passage of a current is beset with difficulties, of which the most 

 fundamental is that of discriminating between the galvanometric 

 results of change of resistance and those of change of electromotive 

 force. The first observations of any importance bearing on this 

 subject were those of Professor Hermann, made some years ago, 

 who found that when compared with the resistance of a living 

 nerve, that of the same nerve when devitalised was considerably 

 greater. Prof. v. Fleischl has recently attempted to get over 

 the difficulties with the aid of the capillary electrometer 1 . He 

 found that when he introduced a capillary electrometer into the 



1 E. v. Fleischl, Studien iiber den Electrotonus, ' Arch. f. Anat. u. Phyaiol.' 1885, 

 p.' 490. 



