Prof. Matteucci on the Origin of Muscular Power. 291 



electric current possible to excite contraction, it is easy to deter- 

 mine the quantity of zinc oxidized in the battery during the 

 passage of the current which is employed to excite the nerve 

 and produce contraction. Whatever may be the theoretical, 

 or rather hypothetical idea which is formed, as to the manner 

 in which the electric current acts upon the nerves, it is impos- 

 sible to deny that there exists some connexion between the 

 quantity of zinc oxidized in the battery and measured in the 

 voltameter, the electric current thus obtained, and the corre- 

 sponding nervous excitation produced. It results, from a great 

 number of experiments of a kind admitting of no uncertainty, 

 that the work produced by muscular contraction is enormously 

 greater than the corresponding chemical or calorific work in the 

 battery. It necessarily follows from this, that the nervous irrita- 

 tion cannot act without having previously given rise to the com- 

 bustion of the organic matters, azotized or non-azotized, which 

 accompanies muscular contraction. 



I have still to add a remarkable relation between these pheno- 

 mena and the electromotive force of the muscles. It may be 

 illustrated by one of the most beautiful and certain of electro- 

 physiological experiments, which consists in closing the circuit of 

 the galvanometer with two equal and opposed muscles, such as 

 the two half-thighs (demi-cuisses) of a frog, which touch each other 

 by the two interior sections. There is no current perceptible to 

 the galvanometer when the preparation is well made. If con- 

 traction be now produced in one of the half-thighs several times 

 in succession, and the circuit be closed after as before, there is 

 obtained a very marked differential current, the direction of 

 which indicates the superiority of the electromotive force of the 

 muscle left at rest. It may be here remarked that this result 

 cannot be explained by attributing it to the acid which may be 

 supposed to be set free by the contraction • for on this hypo- 

 thesis the differential electric current would be in the opposite 

 direction to that which is actually observed. We are therefore 

 driven to the conclusion that during muscular contraction there 

 are such chemical changes in operation as weaken the electro- 

 motive force of the muscle. 



Believe me, yours truly, 



C. Matteucci. 



U2 



