ON THE PROPER CURRENT OF THE FROG. 301 



to the muscular surfaces. It is sufficient to introduce the thighs into this pile, to 

 put, that is to say, the interior of the muscle in contact with the tendinous extremity, 

 for the sign of the current to be inverted, and the muscular current produced (fig. 12.). 

 This proves how necessary it is, in order to have the signs of the current directed 

 from the tendon to the muscle, not to comprehend any portion of the interior of the 

 muscle in the circuit. 



Let us then conclude, that " touching a mass of muscle belonging to a living animal, 

 or an animal recently killed, with a homogeneous conducting arch, one extremity of 

 which is contact with the tendon of the muscle, and the other with the superficies of 

 the muscle itself, signs of an electric current are obtained, which circulates in the 

 muscular mass, its direction being from the tendon to the external surface of the 

 muscle." 



This fact comprehends that of the proper current of the frog. 



Let it not be forgotten that from the sum of all our researches, it has been proved 

 that both the muscular and proper current are subject to the same laws, and thus in 

 all probability have a common origin. I would here again call the attention of ana- 

 tomists to the study of the structure of the muscles, and of the relation which exists 

 between the muscular fibres, the tendon, and the membrane which invests the fibres 

 or the sarcolemma. 



If I have rightly understood the classical labours of my friend Mr. Bowman, it 

 would follow that the extremities of the elementary muscular fibres are immediately 

 connected and continued with the tendinous fibre ; while the sarcolemma which invests 

 the muscular fibre ceases abruptly where the tendon begins. On the strength of this 

 disposition I cannot abstain from emitting an hypothesis upon the origin of the proper 

 current, which would reduce all that we know on the subject of animal electricity to 

 one principle alone. Let it be granted that the tendinous fibre, from its structure, 

 from its connections with the muscular fibre, and from its conductibility, represents 

 the internal part of the muscle, and that the sarcolemma, on the contrary, is distin- 

 guished under this aspect from the muscular fibre ; then the case of the proper cur- 

 rent, or of the current from the tendon to the muscular surface, becomes at once the 

 simplest and most general case of the muscular current. We must never forget the 

 analogy between the muscular electro-motor element and the Voltanian element : 

 the zinc is represented by the discs of the muscular fibre, the acid liquid by the 

 blood, the platinum by the sarcolemma. Whatever be the conducting body with 

 which the zinc is made to communicate with the platinum, the current is always in 

 the same direction. If it be well proved by anatomy that the tendinous extremities 

 are continuous with the extremities of the niuscular fibres, and that the sarcolemma 

 which envelopes the muscular fibre alone, and not the tendon, is not continuous, is 

 not as it were identified with the muscular fibre, the analogy between the muscular 

 element and that of Volta is complete and perfect. 



The chemical actions of nutrition evolve electricity. 



Pisa, April 7, 1845. 



2 r2 ' 



