GENERAL PHYSIOLOGY OF MUSCLE 75 



aa compared with the artificial transverse or oblique section, even 

 when it is not the natural external surface covered with periraysium, 

 but the surface of a bundle of fibres artificially dissected out, but 

 otherwise intact. On the other hand, the natural transverse or 

 oblique section, consisting of the ends of the fibres where they are 

 connected with the tendon or aponeurosis, is not like the artificial 

 surface produced by a cut negative to the longitudinal surface. 

 The negative charge first makes its appearance after removal of 

 the tendon, i.e. on the formation of an artificial cross-section. 



The gastrocnemius muscle, which is generally employed for a 

 nerve-muscle preparation from the frog, shows marked differences 

 of potential at different points of its natural surface, which do not 

 altogether conform to the laws of the current of rest in straight or 

 oblique muscle cylinders. This is due to the complicated structure 



FIG. 52. Measurement of electromotive force of current of rest in muscle by method of compensa- 

 tion, r r, rectilinear rheochord (monochord) consisting of a long wire connected at the ends 

 to the battery. The runner s is movable along it, so that any fraction of the battery current 

 can be thrown into the galvanometer to compensate the muscle current which is opposite 

 in direction. 



of the muscle, which consists not of parallel fibres, but of fibres that 

 run obliquely (Kosenthal). 



The electromotive force which a frog's muscle is capable of 

 developing may be measured by the compensation method, i.e. by 

 introducing into the circuit that connects the two oppositely 

 charged points of the muscle with the galvanometer a current 

 from a Daniell cell in the direction opposite to, and of the same 

 strength as, the muscle current. This is easily effected by means of 

 a rheochord (Fig. 52). The electromotive force has been known to 

 exceed 0'08 volt (du Bois-Reymond, Chapman). But it may be 

 concluded that the portion of the current led off to the galvano- 

 meter is only a small fraction of the total current developed 

 within the muscle, which we are not in a position to measure 

 (Bernstein). 



The electrical phenomena of the resting muscle depend on the 

 state of vitality of the tissues. Muscles that are dead or in rigor 

 mortis are electrically inactive. Muscles treated with ether vapour, 



