LECT. XIV. XV. INDUCED CONTRACTIONS. 289 



nomena of the nutrition of the muscle, has an analogous 

 action upon its contractibility, provoked by any influence 

 acting upon the nerves; and, lastly, in the laws of the con- 

 traction of a muscle, we find an analogy with the physical 

 laws of elasticity. 



The fact of induced contraction will, then, be a pheno- 

 menon of induction of this unknown force, which circulates 

 in the nerves and produces muscular contraction. 



By assuming as well-proved, that the phenomenon of in- 

 duced contractions could not be satisfactorily explained by 

 having recourse to the electric current, as I believe I have 

 completely placed beyond doubt, it appears to me that we 

 cannot, in speaking of a fact as simple as that of induced 

 contraction, assume any other interpretation than that which 

 we have given. The induced contraction will be a new 

 phenomenon of the nervous force, a phenomenon of which 

 we have already given the principal laws. To me it would 

 seem most rational henceforth to call that muscular induction, 

 which we have hitherto termed induced contraction. 



A muscle in contraction exercises an inductive action 

 upon a living nerve. After all, I am compelled to say that, 

 recently, I have resumed the examination of the induced 

 current, by considering it as due to a very feeble electric 

 discharge analogous to that of the Leyden jar. After 

 having seen that excessively feeble discharges produce 

 contractions in frogs, knowing that the presence of these 

 discharges cannot be detected either by the galvanometer 

 or any other instrument, but only by the frog, it appeared 

 worth while to ascertain whether a very slight discharge of 

 the Leyden phial, traversing a muscle, acted on the nerve 

 of the galvanoscopic frog, and under the same laws that 

 we have found induced contraction to do. I must admit 

 that, notwithstanding a great number of endeavours, I have 

 not been able to discover any differences. I wish, then, to 

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