on 3Iuscular Action through the Nerve. 39 



that the acid being a stronger muscular excitant, the effects 

 were due to the acid getting upon the muscle ; to avoid this 

 a small quantity of oil was smeared over the surface of the 

 muscle previous to applying the acid, so as to prevent its 

 action, but the same effects were obtained. 



The results of this inquiry go far to confirm the conclu- 

 sion of Matteucci, that when an electric current has traversed 

 a nerve and is then suspended, the tetanic contractions pro- 

 duced are due to a secondary electro-motor power established 

 in the nerves. If the current be sufficiently strong, there 

 is an electrolyzation of the nervous structure, and conse- 

 quently, an acid developed at the anode and an alkali at 

 the cathode ; as these tetanic contractions are principally 

 observed in the limb in which the current has been inverse, 

 it corresponds to the acid being developed near the muscle, 

 and the alkali at the distal extremity ; and upon the suspen- 

 sion of the current, the current arising from the combina- 

 tion of the compound formed during the electrolyzation of 

 the nervous tissue is then directed towards the muscle, as 

 shown by Matteucci. That the tetanic contractions should 

 be more prolonged after the passage of the electric current, 

 than when the solutions are applied, as in these experiments, 

 is what one would naturally expect, considering that the 

 changes were, in the one case in the substance of the nervous 

 tissue itself, and in the other, merely between the solutions. 

 We have therefore no evidence for believing that the so- 

 called electro-tonic* state of the nerve (electrotonus) is any- 

 thing more than the secondary electro-motor power of the 

 nerves induced by the electric current. Tlie contractions 

 of the muscles becoming, in fact, a galvanoscopic test of the 

 chemical and electrical changes which take place in its own 

 nerve. 



* It is interesting to observe whence the origin of the term electro-tonic 

 arose. Faraday employed it in his first series of papers (Experimental Researches, 

 vol. i. p. 16) to indicate the peculiar state in which a wire was supposed to he 

 brought, when subject to volta-electric or magneto-electric induction ; but he 

 subsequently found that the supposed effects could be fully explained without 

 admitting the electro-tonic state. 



