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electric current in portions of nerve detached from the body, a 

 current which, like that of muscle, passes, in the galvanometer, from 

 the surface of the nerve to the interior. He adds, that he could 

 perceive no marked difference in the relative duration of the electro- 

 motive power of muscle and nerve. 



In the third section, the author discusses anew, and with the aid 

 of fresh experiments, the phenomenon originally named by him in- 

 duced contraction, in which the nerve of a " galvanoscopic limb " of a 

 frog, being laid on a muscle of a living or recently killed animal, is sti- 

 mulated by the contraction of that muscle, so as to cause at the same 

 moment contraction in the muscles of the galvanoscopic limb. He 

 endeavours to show, that this phenomenon is due to an actual electric 

 discharge, which takes place in a muscle at the moment of contrac- 

 tion, in an opposite direction to the ordinary current of the muscle 

 while at rest. The deviation of the galvanometer-needle during the 

 contraction of a muscle, which occurs in an opposite direction to 

 that previously caused by the electric current generated by the 

 muscle while at rest, was ascribed by M. Du Bois Reymond to the 

 diminution or cessation of the latter current when the muscle con- 

 tracts, and to the operation in such circumstances of the secondary 

 polarity of the platinum plates of the galvanometer. Professor 

 Matteucci, however, adduces various experiments to show, that, by 

 certain arrangements described, he is able entirely to prevent the 

 occurrence of secondary polarity, and that nevertheless the deviation 

 of the needle takes place. 



After adverting to the want of reliable data on which to found an 

 explanation of the physical cause of the phenomenon in question, the 

 author hints, that as there is no analogy between the form of the 

 voltaic electromotor and that of the molecular electromotor, it is not 

 impossible to conceive that the change of form which takes place in 

 a muscle during contraction may be momentarily followed by the 

 inversion of the muscular current in the exterior arc. He observes, 

 that examples are not wanting, taken from certain cases of electro- 

 dynamic induction, and also of voltaic circuits, in which this inversion 

 of the current can be obtained by a change in the form, or relative 

 distance of different parts of the circuit ; but he adds, that this is a 

 new field of inquiry, which cannot be given up to merely hypothetical 



