28 On the Effects of Certain Physical and 



which I may detail, and which I believe to have been most 

 carefully as well as very repeatedly observed. 



When a muscular nerve, and, as will be shortly stated, 

 when the spinal marrow is made the conducting medium of 

 the Voltaic influence, there is at the moment of completing 

 the circuit, and once only, a degree of muscular contraction 

 proportionate to the power of the agent and the susceptibility 

 of the animal. 



This phenomenon is repeated on breaking and recom- 

 pleting the Voltaic circuit ; and if this be done rapidly, as in 

 the case in which the connections of the apparatus and of the 

 nervous tissue is not uniform and continuous, repeated con- 

 tractions are produced. On breaking the circuit, after its 

 completion has been continuous during a certain space of 

 time, a tetanoid state is observed, — the effect, as I have sug- 

 gested, of a slow and interrupted discharge of the electro- 

 genie condition of the nerve into the muscles. The precise 

 direction and condition of this' discharge in the muscle or 

 muscles require investigation. It is especially a question, 

 Whether a Voltaic circle be formed within these organs X 



In addition to the electrogenic condition of the spinal mar- 

 row and of the incident nerves, the following circumstances 

 will be submitted to the consideration of the Society in this 

 paper, viz., that, 



1. The electrogenic state of the nerves admits of being 

 discharged, and is capable of inducing the phenomena of Vol- 

 taism in other nerves. 



2. This state is inducible by momentary and slight Voltaic 

 currents. 



3. It is more inducible by the reverse than by the direct 

 Voltaic current, as stated by Signor Matteucci and others. 



4. When a nerve forms a part of the Voltaic circle, new 

 and superadded circles may be effected, which, by inducing a 

 change in the condition of the first, result in the phenomena 

 of muscular contractions. 



5. When the Voltaic circle is either complete, or, having 

 been completed, is broken, and various parts of the wires and 

 animal tissues, which form or formed that circle, are con- 

 nected by a conductor, a series of phenomena is produced, 

 some of which still require explanation. 



