ELECTEO-PHYSIOLOGY. 327 



batteries. The muscular elements, which arc most readily supplied, are the half 

 thighs of frogs. With this view a certain number of frogs are prepared a la 

 Galvani, the legs of which are cut at the articulations ; then, by dividing trans- 

 versely at the middle of the thigh, we obtain, especially with the inferior half, 

 a perfect element. Muscular elements with divided fibres are also procured by 

 removing the skin of an eel, and cutting it transversely into so many pieces ; 

 and in like manner from the legs of birds and mammifers stript of the skin. 

 The heart of a bird or fish cut in half likewise furnic^hes a muscular element, 

 and the same may be said of slices of the pectoral muscles. Whatever be the 

 muscular element thus obtained, it is readily understood how a muscular bat- 

 tery may be formed of a certain number of these elements: it sufiices to arrange 

 all of them in the same direction, that is, by causing the interior or section of 

 an element to touch the surface of the succeeding element. Similar batteries 

 have been constructed even on the still living muscles ; for this purpose the 

 frogs were fixed upon a table, their lower members denuded of skin, and a thigh 

 of each was cut in the middle. The battery Avas completed by establishing the 

 contact between the section created by cutting in one frog and the leg of the 

 succeeding frog. A similar experiment has been repeated with birds. Which- 

 ever of these batteries may be adopted, there occur at the galvanometer currents 

 which increase with the number of elements, and with which we may obtain 

 the discharge of the condenser and the signs of electro-chemical action on the 

 ioduret of potassa. Even with a single pit.ce of divided muscle and the very 

 delicate galvanometer, we observe the indications of the same muscular current, 

 which is constantly directed in the muscle from the internal or transverse section 

 to the sm-face, and thence again to the transverse section in the circuit of the 

 galvanometer. 



As, while studying the current in entire muscles, we saw it always become 

 "Weaker, and finally even null, when the tendinous extremities of the muscle, or 

 two symmetrical points of it nearest to those exti'emities, were touched ; so it 

 will be seen even more generally tliat the muscular current is annulled. in a 

 muscle having two transverse sections equidistant from its middle, on applying 

 the extremities of the galvanometer at the centre of those sections. The ex- 

 periment may be made by cutting transversely, at two points equidistant from its 

 middle, the thigh of a fi-og. By employing the delicate galvanometer, and 

 using for its extremities cushions reduced to a point, we are enabled to operate 

 on small pieces of muscular fibi'c, and to obtain in these that Avhich is obtained 

 with a muscular battery. We are led from the above considerations to gene- 

 ralize the experiments cited, and to conclude that every element of muscular 

 fibre of an animal living or recently killed is an electro-motor. 



Du-Bois -Heymond regards the electro-motor power of entire and of divided 

 muscles under a single point of view, and as having the same origin. In ac- 

 cordance with modern anatomical observations, it is now admitted that the ex- 

 tremities of the muscular fibres, the bases of those cylindrical fibres which 

 compose the muscles, are in immediate communication with the tendinous fibres. 

 For this reason the tendons may be considered in the muscular electro-motor as 

 a natural transverse section. Hence Du Bois Reymond calls the interior or the 

 incision of a muscle the artificial transverse section, and the tendon the natural 

 transverse section. To complete this definition, the same physiologist calls the 

 surface of the muscle the natural longitudinal section, and maintains that we 

 can also obtain, Avhat is sufiiciently difficult in practice, an artificial longitudinal 

 section. These definitions being premised, every muscular electro- motor is 

 embraced under this general formula : any point of the longitudinal section of 

 a muscle, whether natural or artificial, is positive with respect to ever// point of 

 the transtH'rse section, natural or artificial. 



It might be proper to proceed now to a consideration of the muscular electro- 

 motor in its analogy with the different electro-motors which Ave possess in 



