2IO 



MUSCULAR CONTRACTION. 



dead man's foot. Then the experiment ended by 

 applying the battery to revive the muscular action 

 of the impromptu patient. The blow was a start- 

 ling demonstration of the efficient energy of elec- 

 tric currents in developing animal motive-power, 

 and of the fact that nerves and muscles are 

 electrodes. 



It has been suggested by P. M. Roget, that the 

 contraction, or shortening, of the muscles may be 

 the result of the reciprocal attraction which ensues 

 between two portions of conducting matter serv- 

 ing to transmit electric currents in similar direc- 

 tions. 



A piece of wire wound in a spiral coil and placed 

 in the circuit of a galvanic current, becomes instan- 

 taneously shortened or contracted by the lateral 

 forces exerted between 

 each approximated coil, 

 whenever the electric 

 current is transmitted 

 through it. The discov- 

 ery, by microscopic ob- 

 servation, of spiral coils 

 in the cells of plants, 

 and also of similar ar- 

 rangements of the fibres 

 of animal muscles, strongly corroborates this sup- 

 position. In Fig. 65 the wire coil is suspended 

 vertically over a glass cup filled with mercury, its 

 lower extremity just dipping into it. The electric 



