338 ELECTRO-PHYSIOLOGY CHAP. 



current is a property of living tissues, it would still only appeal 

 to us as a vital phenomenon of the first interest if it could be 

 proved that du Bois-Eeymond's law of the equivalence of natural 

 and artificial sections was universally valid, i.e. that a P.D. 

 between the tendon end and remaining surface of the muscle, 

 corresponding with the muscle current, is demonstrable in all 

 cases ; in other words, if the " pre-existence " of the muscle current 

 in intact living animals were a proved conclusion. But this, as 

 we shall see, is by no means the case ; on the contrary, the result 

 of the innumerable experiments of a later date has been more and 

 more in favour of the view upheld by Hermann, to the effect 

 that the muscle current is not pre- existent, but is an artificial 

 effect of the preparation. Matteucci long ago maintained that 

 there was no trace of a muscle current in the uninjured living 

 animal. According to him the current arises from the leading- 

 off contacts. Du Bois-Eeymond, who (supra) adopted the theory 

 of a constant difference in potential between the achilles tendon 

 (natural section) and uninjured surface of the muscle, chiefly on 

 account of his first experiments with the frog's gastrocnemius, 

 was subsequently obliged to modify his opinion. The starting- 

 point of these last investigations of du Bois-Eeymond was a 

 series of observations on the effect of cold on the muscle current, 

 which, as Matteucci had pointed out, produces a marked diminu- 

 tion. Du Bois-Eeymond upon the whole confirmed Matteucci's 

 conclusions as to decreased action in the muscles of cooled frogs. 

 Gastrocnemii (which, on leading off from tendon and natural 

 longitudinal section, invariably gave, according to du Bois- 

 Eeymond's original theory, a vigorous normal current) exhibited 

 negative or reversed effects in the sense of a descending muscle 

 current, while directly an artificial cross-section was provided 

 they yielded an ascending current. Du Bois-Eeymond designated 

 the state of muscle induced, as he thought, by cold, the "parelectro- 

 nomic" state (irapavofjio^ = against the law), because it gives no 

 electromotive response, or even reacts in the opposite direction. 

 The fact that these parelectronomic muscles resume their ''normal" 

 activity from the moment they are laid upon pads of salt clay 

 coated with an albuminous membrane, is due, however, less to warm- 

 ing than to the slow chemical alteration (corrosion) of the tendon, 

 which is in contact with the concentrated salt solution of the lead- 

 ing-off electrodes and the albumen of the membrane. These fluids 



