98 NERVOUS SYSTEM. 



force. It is evident, also, that nearly all of the so-called 

 vital phenomena are more or less influenced and controlled 

 through this wonderful agent ; and throughout our study of 

 the nervous system, we shall be constantly investigating the 

 phenomena attending the operation of nerve -force, while 

 compelled to admit our ignorance of its essential nature. 



Non-identity of Nerve-Force with Electricity. When we 

 come to study fully the action of electricity upon the nerves, 

 we shall see that this is by far the most convenient stimulus 

 for exciting the nervous action, and one by which we closely 

 imitate the true nerve- force. So great is the similarity, in- 

 deed, between some of the phenomena produced by the ap- 

 plication of electricity and those attending the physiological 

 action of nerves, that some physiologists have regarded the 

 nerve-cells as generators of an electric current. This hy- 

 pothesis explains the nature of nerve-force, in so far as it 

 assimilates it to a force, with the action of which, as artifi- 

 cially generated, we are more or less familiar. No one at 

 the present day, however, pretends that the nerve-force has 

 been demonstrated to be identical with any form of elec- 

 tricity ; and the question does not now demand extended 

 discussion. 



A series of experiments made by Prevost and Dumas, 

 in 1823, are worthy of note as showing the absence of a true 

 electric current in nerves in action ; 1 but these have been 

 confirmed in later years with apparatus sufficiently delicate 

 to settle the question beyond a doubt. The most conclusive 

 experiments on this subject are those of Matteucci and Lon- 

 get, made upon horses at the veterinary school at Alfort. 

 These physiologists exposed the sciatic nerves in 'the living 



1 PREVOST ET! DUMAS, Memoire sur les phenomenes qui accompagnent la con- 

 traction de la fibre mu&culaire. Journal de physiologic, Paris, 1823, tome iii., p. 

 328. Analogous experiments, with the same results, were made later by Person 

 (Sur Thypothese des courans electriques dans les nerfs. Journal de physiologie^ 

 Paris, 1830, tome x., p. 216, el seq.). 



