PHILOSOPHICAL SOCIETY OF WASHINGTON. 57 



moment give my adherence to the dogmatism of those modern 

 vitalists who insist that the contractions of a muscle, or of an 

 amoeba, are essentially vital phenomena ; for this would be to claim 

 that life can create force. But it would be folly to shut our eyes to 

 the circumstance that no chemico-physical explanation of muscular 

 contraction yet offered has been so convincingly supported by facts 

 as to command the universal assent of competent physiologists. 



Of the various hypotheses devised to explain muscular contrac- 

 tion, those which regard the phenomena as in some way resulting 

 from electrical disturbances have long enjoyed great popularity. 

 Such of these hypotheses as still survive are based upon the elec- 

 trical manifestations actually observed in living muscles. It has 

 been pretty generally accepted in accordance with the observations 

 of Du Bois-Reymond, whose brilliant series of experiments in animal 

 electricity u is deservedly renowned, that even quiescent living 

 muscles are in a state of electrical tension. If, for example, a 

 muscle composed of parallel longitudinal fibres, be exposed with 

 suitable precautions, and divided near each extremity by a trans- 

 verse incision, the surface of the muscle will be found to be positive 

 to the cut ends, and if one of a pair of nou-polarizable electrodes, 

 connected with a suitable galvanometer, is placed in contact with 

 the surface of the muscle and the other in contact with one of the 

 cut ends, the existence of a current is made manifest. The con- 

 ditions are, moreover, such that while the maximum effect is pro- 

 duced when the equator of the surface is connected with the centre 

 of one of the cut ends ; more or less current will also be manifested 

 whenever any two points of the surface are thus connected with the 

 galvanometer, provided they are not equidistant from the equator. In 

 such cases the point most distant from the equator is always negative. 

 The electro-motive force of this natural current of the quiescent 

 muscle varies greatly, but has been found by Du Bois-Reymond to 

 amount sometimes to as much as .08 Daniell in one of the thigh 

 muscles of the frog. 12 In muscles of different form, or cut dif- 

 ferently from what has just been described, the currents are some- 

 what differently arranged, but the example just given must suffice 

 for my present purpose. 



In accordance with the observations of the same investigator, 

 it is claimed that during a muscular contraction the electrical ten- 

 sion diminishes, the normal muscle-current experiences a negative 

 variation, and this occurs in such a way, that as the wave of actual 



