I'RESENT STATE OF OKGANIC ELECTRICITY. 333 



nerve in such a manner as to increase the force of the ordinary 

 current at that extremity of the segment where tliey correspond 

 in direction, and to diminish .the ordinary current at the other 

 extremity wliere they are opposed. That a new condition of 

 electric tension is induced l)y the exciting currents along the 

 entire segment is proved hy the galvanometer, which indicates 

 a current in the direction of the exciting current between 

 ])oints equally distant from the middle of the outer surface of 

 the segment, where no galvanomctric indications of the ordi- 

 nary current can be derived. 



From the resemblance which this peculiar condition of a 

 nerve bears to the change whicli Faraday supposes to take 

 place in a wire along which a current is induced by a neigh- 

 bouring current, Du Bois Eepnond adopts the term applied 

 by the former to the induced cliange, and denominates the 

 new condition of the ner\'e the eledrotonic state. 



In the electrotonic state the ordinary electromotor elements 

 are evidently polarised, so as to have all their positive and 

 negative poles turned in opposite directions. Du Bois Eey- 

 mond conceives that the change may be explained by assuming 

 that the ortlinary electromotor elements consist each of two 

 dipolar molecules, with their positive poles in contact, and 

 that in the electrotonic condition one of the dipolar molecules 

 of each electromotor element turns on itself from 90° to 100°. 



Tlie Electric Coiiditian of a Nerve during Functional Ac- 

 tivity. — As Du Bois llcymond was the first to detect the 

 ordinary electric cuiTent in nerves, so we owe to him the only 

 information we possess regarding the electric condition of a 

 nerve during functional activity. The question to be deter- 

 mined is the electric condition of a motor nerve while it is 

 engaged in transmitting to a muscle the stimulus which 



• The greater part of the first division of vol. ii. of the UntfrsiuJiungtn 

 is occupied with the subject of the nerve-current. Tlie statement of the laws 

 of tlic uerve-currcut will be found at pp. 2G2, 263. 



