ELECTEO-PHYSIOLOGY. 341 



charges; but this power still persists wlien tlie nerves of the organ have for a 

 long time lost every trace of excitability. I will finally add that the action 

 of the electric organ is not accompanied by the development of caloric, even 

 when the most delicate instruments are uspd to detect it, and that a piece of 

 organ enclosed in a limited space of air may give many successive discharges 

 without producing any sensible modification in the air. 



These conclusions, deduced from rigorous experiments, show the differences 

 which exist between the function of the electric organ and that of the muscular 

 contraction. Without pretending to give the theory of the mode of action of 

 the electric organ, I will not withhold the opinion that these results would be 

 readily explained on the hypothesis that in every cell there are substances of 

 different nature which react chemically by generating electric currents, and that 

 tliese materials are secreted in greater quantity by the excitation of the nervous 

 system. I will merely intimate that these substances might be an acid and a 

 base, and, in passing, notice the fact that if a piece of divided organ be left in a 

 funnel there issues a liquid which after some time has an alkaline reaction ; the 

 aqueous infusion of the same divided organ being slowly evaporated leaves a 

 residuum which yields a very distinct acid reaction. I do not from this f;ict, 

 I repeat, propose to say in what consists the electro-motor power of the torpedo; 

 but certainly the results which I have presented open a new path for investiga- 

 tion in the subject of animal electricity. 



Electrical plienomcna of vuiscular contraction. — In the beginning of 1842 I 

 communicated to the Academy of Sciences of Paris an experiment which has 

 been the origin of an interesting branch of electro-physiology. It was tljps : I 

 prepare one or more galvanoscopic frogs which are placed as usual on the gutta- 

 percha support, and I extend the nerves of these frogs upon the surface of the 

 exposed muscles of any animal living or recently killed. To render the experi- 

 ment more easy I take a frog prepared after Galvani's manner and stretch the 

 nerves of the galvanoscopic frogs upon the muscles of its thighs. Whatever be the 

 means used to make these muscles contract, the galvanoscopic frog at the same 

 instant undergoes contraction. If the nerve of the galvanoscopic frog be placed 

 upon the heart of a frog .or other living animal, at every contraction of that 

 muscle the galvanoscopic frog suffers contraction. This phenomenon, which for 

 the sake of brevity I shall call inducted contraction, is realized whatever be the 

 manner in which the nerve is spread upon the muscle, and if the frog, which I 

 term inductive, is very vivacious, the inducted contraction is obtained even by 

 placing the nerve on the extremity of the foot, or by detaching promptly a por- 

 tion of muscle and forcing it to contract by incisions in different directions. In 

 this respect the experiment of inducted contraction appears analogous to the 

 discharge of the organ of the torpedo. 



There exists no other organic tissue which, irritated in whatsoever manner, 

 excites the inducted contraction ; the muscle itself, if taken from a frog killed 

 with curare, or with tendons so divided that contraction does not occur, will not, 

 on irritating the nerve, give rise to the inducted contraction. On the other hand, 

 by having several galvanoscopic frogs freshly prepared and very vivacious, and 

 aa'rauging them in series — that is, placing the nerve of one on the gastrocnemius 

 of another — all will be seen to fall into contraction when one of the extreme ones 

 i.^ made to contract. This is what may be termed having inducted contraction 

 of the second, of the third order. Attention has been directed to the influence of 

 bodies interposed between the nerve of the galvanoscopic frog and the muscle 

 in contraction, and it has been found that a good conducting stratum, leaf-gold 

 for instance, or a solid isolating stratum, though extremely thin, alike hinders the 

 inducted contraction. On the supposition that the phenomenon is analogous 

 to the discharge of the torpedo, we can understand how the conducting metallic 

 stratum, by allowing the discharge to pass entirely within itself, hinders the 

 effect of it on the nerve. A stratum of oil or of turpentine was interposed and 



