284 NERVOUS FORCE. LECT. XIV. XV- 



gated to the nerve of the frog, and takes no part in the 

 phenomenon.* How can the induced contraction of the 

 second and third order be understood? In what way can 

 we explain the fact, that the induced contraction is wanting, 

 even when the current has been, as usual, applied upon the 

 lumbar plexuses, and that only because by the incision of the 

 nerves in the thigh, we have abolished, or greatly diminished, 

 the inducing contraction? Why does the induced contrac- 

 tion fail when we apply the same current in the nerve 

 below the thigh, in which case the muscles of the thigh do 

 not contract? Why, when we operate with the current 

 upon the lumbar plexuses of a frog, already weakened to 

 such a degree that it only excites contractions at the com- 

 mencement of the passage of the direct current, or at the 

 moment of the interruption of the inverse one ; why, I say, 

 is there, in this case alone, induced contraction ? It is use- 

 less to continue to reconcile the objections we can make to 

 the interpretations of this phenomenon, by having recourse 

 to a diffusion of current to produce the inducing contrac- 

 tions, a diffusion which we can in no way comprehend 

 physically. 



2dly, We might suppose that the induced contraction is 

 the effect of a mechanical stimulant, namely, of the contrac- 

 tion of one of the inducing muscles, which thus gives a 

 shock to the galvanoscopic frog. 



I have tried a great number of times, by using very sen- 

 sitive galvanoscopic frogs, to excite, by all possible means, 

 some movements in the muscles of the thighs, without 

 causing the galvanoscopic frog to contract. If the true 



* From excessive precaution, I have often tried to obtain the induced 

 contraction by exciting the inducing ones by lacerating the spinal marrow 

 with a piece of glass. The induced contraction took place as if the in- 

 ducing had been excited by the current or any other stimulant. Note by 

 Matteucci. 



