Prof. Matteucci's Electro-Physiological Researches. 455 



cause a rise of temperature amounting to about half a degree Centi- 

 grade. 



The second section is devoted to the consideration of the electric 

 current exhibited by muscles at rest, and experiments are adduced in 

 illustration of the following propositions : — 



a. The electro-motive power of a. cut muscle is independent of the 

 size of its transverse section. 



b. The electro-motive power increases with the length of the 

 muscle. 



c. The electro-motive property of the muscles of living or recently 

 killed animals is greater in mammals and birds than in fish and 

 amphibia. The duration of this force, which in all cases decreases 

 most rapidly in the first moments after death, is greater in fish and 

 amphibia than in the higher orders of animals. 



d. The nerves have no direct influence on the electro-motive force 

 of muscles. In general, all causes which exert an influence on the 

 physical structure and chemical composition of muscles, so as to 

 modify, in ways unknown, their irritability or contractility, act equally 

 on their electro-motive power. 



Prof. Matteucci here takes occasion to state, that he has verified 

 the important discoveiy of Du Bois Reymond, of the existence of an 

 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 diflTerence 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 neeJle takes place. 



After adverting to the want of reli.able 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 



