262 On the Effects of Certain Physical and 



On breaking the circuit and connecting the wires, and on 

 disconnecting and reconnecting them, there was invariably a 

 distinct muscular action. 



Ex. 4. "We prepared a frog, as in figure 1, and placed the 

 silver discs under its feet. Little effect was observed on 

 completing the circuit, and none on breaking it. We then 

 reduced the frog to the condition i*epresented in fig. 4, and 

 the phenomena just detailed, as observed in the last experi- 

 ment, were again reproduced, viz. ; spasmodic contractions 

 of the muscles on breaking the circuit, which ceased on re- 

 making it. 



On surrounding the nerves with the moist intestines, the 

 phenomena of making and remaking the circuit, or of con- 

 necting the wires or shillings, again ceased, and again re- 

 curred on denuding the nerves ; effects reproduced several 

 times, by repetition of the application and removal of the 

 moist covering of the nerves ; the contact of the femora 

 broken and renewed several times, also permitted or pre- 

 vented the phenomena of the connection of the silver discs. 



Having prepared a frog as in figure 4, but without apply- 

 ing the Voltaic influence, we brought the silver discs (bright 

 shillings) into contact, or connected them by a curved pla- 

 tinum wire ; there were slight but distinct contractions of 

 the muscles : for the silver we now substituted platinum ; 

 there were no movements, or movements of the very slightest 

 kind. 



Retaining the platinum plates, we now completed the Vol- 

 taic circuit as in fig. 4. Having waited five minutes for elec- 

 trogenic indiiction, we interrupted the circuit, and again con- 

 nected the platinum plates, smaller platinum plates placed on 

 the femoral muscles, and the platinum wires, in different 

 points of their course, always with spasmodic action of the 

 muscles. 



Ex. 6. We prepared a frog as in fig. 4. After breaking 

 the circuit, we covered one of the nerves with the moist in- 

 testines, and connected the platinum plates. One limb only 

 was moved, that the nerves of which were left denuded. 



We removed the intestines, and again connected the pla- 



