PRESENT STATE OF ORGANIC ELECTRICITY. 333 



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

 current at that extremity of the segment where they correspond 

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

 extremity where they are opposed. That a new condition of 

 electric tension is induced by the exciting currents along the 

 entire segment is proved by the galvanometer, which indicates 

 a current in the direction of the exciting current between 

 points equally distant from the middle of the outer surface of 

 the segment, where no galvanometric indications of the ordi- 

 nary current can be derived. 



From the resemblance which this peculiar condition of a 

 nerve bears to the change which Faraday supposes to take 

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

 bouring current, Du Bois Eeymond adopts the term applied 

 by the former to the induced change, and denominates the 

 new condition of the nerve the electrotonic 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 ordinary 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.* 



The Electric Condition of a Nerve during Functional Ac- 

 tivity. As Du Bois Eeymond was the first to detect the 

 ordinary electric current 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 Unterwwhungen 

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

 of the nerve-current will be found at pp. 262, 263. 



