326 ELECTEO-PIIYSIOLOGY. 



ever be the entire muscle operated upon, if this muscle is alive or belongs to an 

 animal recently killed, a current is obtained in a homogeneous arc which touches 

 with its extremities one of the tendinous extremities of the muscle and the sur- 

 face of the muscle ; this current is constantly directed in the external arc from 

 the surface of the muscle to the tendon, and its intensity diminishes in proportion 

 tts both the extremities of the arc separate from one another by approaching the 

 extremities of the muscle." This proposition, suitably applied, comprises all 

 the cases of currents obtained in entire muscles, and ia confirmed by operating 

 on the muscles of frogs, insects, and animals of warm blood, but with difference 

 of intensity and lapse of time after death, depending upon laws which will be 

 considered in the sequel. 



It has already been said that the current obtained by Nobili, in operating on 

 the entire frog, was in some sense the algebraic expression of all the currents of 

 the muscular fasciculi, which compose the animal, and which are included in the 

 circuit at the same time. It will suffice to form a double battery, by opposing a 

 single gastrocnemian to an entire half of the frog, in order to obtain in the galva- 

 nometer a strong dilferential current in the direction of the single gastrocnemian. 

 1 will merely add that, with a battery formed of ten or twelve gastrocnemians, I 

 have been enabled to obtain a current so intense as to discharge the condenser 

 and to give indications of electro-chemical decomposition. 



The current with which Ave have been till now occupied, and which is found 

 in entire muscles, is evidently the cause of the contraction which occurs in the 

 experiment of Galvaui on touching the muscles of the leg with the lumbar 

 nerves. This current, proceeding from the feet to the head in the frog, is 

 inverse as regards the lumbar nerves — that is, in the direction in Avhich we have 

 Been the contraction prevail at the opening of the circuit. We have observed, 

 on the other hand, in repeating the experiment of Galvani, that the contraction 

 is more frequently obtained when the nerves and muscles touch each other, and 

 not in the act by which that contact ceases. To explain this result, which 

 would seem contrary to the law which has been stated respecting the physio- 

 logical action of the current according to its direction, we must observe that in 

 making the experiment of Galvani it may not happen that the circuit is kept 

 closed for a certain time, while this condition is indispensable for obtaining the 

 contraction at the opening, when the nerve is traversed by the inverse current. 

 And, in fact, if the experiment of Galvani be repeated by prolonging the contact, 

 we then generally succeed in obtaining the contraction when the current ceases. 

 Professor Cima has pointed out a certain method of obtaining, with the current 

 of the frog, contraction at the opening of the circuit. He takes the galvano- 

 scopic frog, rests it on an isolating support, and then immerses in water at the 

 same time the fore paw and the end of the nervous fibre which hangs below; 

 then, by keeping the circuit closed each time for several seconds, we obtain the 

 contraction, lirst at the closing and opening of the circuit, and afterwards only 

 ivt the opening. 



Let us pass now to the electric current obtained in muscles in which the 

 fibres are divided. The first exp;n-iment of this kind which seems to have 

 been tried is that which I now exhibit, and which is performed by using the 

 galvanoscopic frog rapidly prepared, and supported on an isolating handle of 

 gutta-percha. I take another frog, a living fish, bird, or any animal whatever, 

 and make an incision in a muscular mass ; I then cause the nerve of the 

 galvanoscopic frog to touch with two different points the intei'ior of the in- 

 cision and the surface of the muscle. In this way we never fail of obtain- 

 ing a contraction in the frog, and, by making the experiment with due care, 

 we may even succeed in determining in the usual manner the direction of the 

 current, that is, the position of the poles of the muscular electro-motoi*. 



If the not very delicate galvanometer be used, the effects of the muscular 

 current obtained from divided muscles are augmented by forming the usual 



