232 ELECTRIC CURRENT. L.ECT. XII. XIII. 



more of the liquid ; and the frog does not suffer any effect 

 at the commencement of the current, but only at its inter- 

 ruption. 



Effects on the Muscles. We have hitherto caused the 

 current to act on the nerves of animals, and have deter- 

 mined the laws of this action. We have also examined 

 the case in which it circulates in the entire animal, by tra- 

 versing at the same time nerves and muscles. It remains 

 now for me to notice the action of the current on the mus- 

 cular fibre alone. 



The difficulty surrounding such an investigation may be 

 easily conceived ; for we cannot with certainty remove 

 every trace of the nervous substance, even when we remove 

 from a muscle all its nervous filaments visible to the naked 

 eye, as well as those which are only perceptible by the aid 

 of a magnifying glass. However, it is upon a muscle thus 

 deprived, as carefully as possible of its nervous filaments, 

 that we are obliged to operate, and the following are the 

 results obtained : 



By passing the current from twenty to thirty elements 

 through the pectoral muscle of a pigeon, from which the 

 nerves have been removed, as just mentioned, we always 

 observe, that contraction takes place when we close the 

 circuit. This contraction, moreover, lasts but for an instant, 

 and appears to consist in a momentary shortening of the 

 fibres. Whatever may be the direction of the current in 

 relation to that of the muscular fibres, the phenomenon is 

 the same. If the circuit be kept closed, and the passage 

 of the current through the muscle be continued, the contrac- 

 tions reappear on opening the circuit. They are weaker 

 than when we close the circuit; r.nd if the passage has been 

 prolonged for some time, they are entirely absent at the 

 interruption of the circuit. 



In general, the contractions obtained by acting on the 



