254 On the Effects of certain Physical and 



nuded on all sides, and raised from the glass on which the 

 animal was placed (see Plate V., fig. 3). 



Having thus prepared the subject of experiment, we ar- 

 ranged the platinum wires, issuing from a pair of cells of the 

 " couronne de tasses" of Volta, and tipped with a platinum 

 plate, so that at one time the wire from the silver should be 

 placed upon the upper parts of the nerves near the spine, and 

 that from the zinc upon the lower part of the nerves near the 

 femora, so conveying a Voltaic current downwards, in the 

 direction of the nerves, /row their origin in the spinal marrow, 

 towards their ramifications and distribution in the muscles, 

 and at another time in the contrary or reverted direction. 



On completing the circuit we had energetic muscular move- 

 ments. 



On allowing the platinum mres and plates to remain in 

 this position, and in this apposition with, and relation to, the 

 lumbar nerves, variously, for the space of five, ten, or fifteen 

 minutes, and then interrupting the A'^oltaic circuit, and re- 

 i^oving all Voltaic influence, we observed the effects of the 

 ^condary or electrogenic condition of the nerves, in the in- 

 stant and most remai-kable spasmodic contractions and teta- 

 noid rigidity of the muscles of both the limbs ; effects which 

 as instantly subsided on the restoration of the Voltaic circuit, 

 and the re-application of the Voltaic influence. 



In this experiment we have the simplest form of electro- 

 genic induction of the nerves, and of its effects, — a condition 

 which, though induced by the Voltaic influence, yet, when 

 induced, is independent of it, and persistent for a certain 

 length of time ; admitting, therefore, of being made the sub- 

 ject of distinct investigation. 



I will take this early opportunity of begging my reader 

 carefully to distinguish between the muscular movements, 

 however energetic, of the first completion of the Voltaic cir- 

 cuit, and the spasmodic or tetanoid condition of the muscles 

 observed as the effect of the electrogenic state, when the 

 Voltaic influence is removed. 



The apparatus which I have hitherto employed has been of 

 the most simple character : from ten to twenty cells of the com- 

 mon trough of Cruickshanks, containing pure water, and con- 



