362 ELECTRO-PHYSIOLOGY 



contraction, and he believed himself to have discovered a special 

 force, manifesting itself by action at a distance, which proceeds 

 from the muscle at the moment of contraction ; this led him 

 to give the name of " induced twitch " to the phenomenon he 

 had discovered. 



Up to this point Matteucci had no knowledge of a 

 discovery made by du Bois-Eeymorid in 1842, in following 

 up an older investigation of the Italian experimenter. As far 

 back as 1838, Matteucci had discovered that the ascending 

 current in the frog (" courant propre ") as demonstrated by 

 Nobili in 1827 with Schweigger's multiplier on galvanic pre- 

 parations, and referred by du Bois to the current of the single 

 muscle disappeared altogether, or was much weakened during 

 tetanus (later, he believed himself convinced of the contrary). 

 Du Bois - Reymond, who had meantime formulated the "law 

 of the muscle current," weut on to ask, How the muscle 

 current behaved during persistent excitation ? The first com- 

 munication of the weighty results of this inquiry appeared in 

 1842, iii a "preliminary sketch." In this it was shown that 

 the longitudinal transverse current of the gastrocnemius did not 

 disappear during contraction, when the nerve was tetanised, but 

 that it did diminish perceptibly in intensity. 



The capital experiment of this investigation was originally 

 arranged as follows (Fig. 112). The gastrocnemius lies with 

 its longitudinal and artificial (or corroded natural) transverse 

 sections upon the pads of the leading-in dishes ; the central end 

 of the nerve is stretched over platinum electrodes, connected with 

 the tetariising apparatus. The experiment invariably results 

 in an unmistakable diminution of the muscle current during 

 tetanus, a negative variation, as seen in the backward swing 

 of the needle of the multiplier, or circular magnet of the 

 galvanometer. All possible objections and sources of fallacy 

 were investigated by du Bois-Reymond with his usual thorough- 

 ness, and he succeeded in establishing beyond doubt that a 

 diminution of E.M.F. does actually accompany the state of excita- 

 tion. In later experiments du Bois investigated the negative 

 variation, with similar results, on the regular parallel -fibred 

 muscles of the thigh, instead of the complicated gastrocnemius, 

 change of form in the muscle being avoided by tension between 

 two fixed points. The method of compensating the " current 



