184 MUSCULAR CURRENT. LiECT. IX. 



of whose spinal marrow I had destroyed some days be- 

 fore with a red-hot iron, or which I had killed by opium ; 

 but no perceptible difference was manifested between the 

 intensity of the current produced by these piles and that of 

 the current caused by the same number of muscular ele- 

 ments taken from the entire frog. 



If you continue experimenting, by means of the gal- 

 vanometer, on a pile, which henceforth we shall call mus- 

 cular, you will readily perceive that the deviations of the 

 needle become more and more slight, and then cease en- 

 tirely. And if you use piles formed of the muscles of ani- 

 mals belonging to different classes, you will observe that 

 the signs of the current diminish the more rapidly, and 

 disappear the sooner, in proportion as the animal which 

 you have been using occupied a more elevated position 

 in the scale of beings. Thus it happens that piles formed 

 by the muscles of fishes, frogs, and eels, give several hours 

 after death, perceptible signs of the current; whilst those 

 which are made with the muscles of birds and mammals, 

 cease to do so at the end of a few moments. We have 

 already noticed the uncertainty of the signs of the current, 

 presented by the galvanometer, when the extremities of the 

 wire of the instrument were put directly in contact with 

 the muscles of the living animal. In this case, in order 

 to be able to establish the facts in a more satisfactory 

 manner, it becomes necessary to vary the mode of experi- 

 menting. 



Here is an experiment which I have made, and which 

 is free from all error; it is only the repetition, upon the 

 living animal, of that which I made upon the demi-thighs 

 of the frogs. You can easily understand how we manage, 

 with great care, to confine, on the tray before spoken of, 

 a certain number of living frogs, by fixing there the four 

 legs by means of four nails, and by placing them thus one 



