36 On the Effects of Certain Physical and 



direct. Now, the inverse current in mixed nerves, is the 

 direct in their incident portions. 



Ex. 16. We prepared a frog, as before, and having divided 

 the junction between the femora, we placed the feet on sepa- 

 rate discs of silver, and passed through them the influence of 

 three Voltaic glasses, so that the direct current passed along 

 the nerves of the left extremity, and the inverse along those 

 of the right. 



On completing the circle, the anterior extremities were 

 moved ; on breaking it, after four minutes, the same pheno- 

 menon was observed. 



This result was obtained several times. 



The proof that the electrogenic state may exert its influ- 

 ence in an incident and retrograde direction in the nervous 

 system, may, therefore, be considered as complete, whilst 

 new light is thrown on that system of incident nerves which 

 has now, for many years, occupied my continued attention. 



III. On Primary and Superadded Voltaic Circuits. 



I have incidentally described the principal phenomena of 

 the primary voltaic current passed severally along the lum- 

 bar nerves, the spinal marrow, and the incident dorsal nerves. 

 These phenomena consist in muscular contractions, which 

 occur when the current is eff'ected, and which, if this current 

 be uninterrupted, cease immediately. 



No author has noticed as they deserve, or as I believe at 

 all, the extraordinary phenomena of Voltaic action in currents, 

 superadded to the primary current. It is, therefore, to these 

 I wish to call the attention of physiologists. 



I will suppose the denuded and insulated lumbar nerves to 

 be included in a Voltaic circuit, proceeding from the " cou- 

 ronne de tasses," or induced by the application of the Voltaic 

 arc of zinc and silver. If now connections be made, so as to 

 eifect new or superadded circles, traceable through the zinc 

 and silver, and the parts so brought into connection with 

 them, muscular movements are produced, affecting parts not 

 aff'ected before, which are new. 



That the new movements depend on new circles formed, 

 is proved by their continuance after the tissues involved in 



