212 ELECTRIC CONDUCTION BY NERVES. 



is an essential salt of the juice of the flesh ; and 

 that the alkaline salt of the phosphate of soda is 

 essential to the constitution of blood, to enable it 

 to perform its functions. Hence it has been con- 

 sidered that the probable function of the substan- 

 ces which give acidity to the juice of the flesh 

 and alkalinity to the blood, is the production of 

 electric currents. When we see two substances, 

 one acid and the other alkaline, in opposite neg- 

 ative and positive conditions, separated only by a 

 thin membrane permeable to both (by endosmose 

 and exosmose action), and in contact with muscle 

 and nervous matter, as observed by Liebig, " we can 

 easily see how electric currents may arise." ] 



The continuous transmission of electric action 

 must be effected by establishing an electric closed 

 circuit. 



M. du Bois-Reymond discovered and established 

 the fact that an electric current exists in nerves, 

 the conditions of which are in most respects simi- 

 lar to that of the muscular current. A change in 

 the electric state of muscles takes place in the act 

 of contraction. 



Professor Matteucci first made a frog galvano- 

 scope. By means of a battery of ten thighs, he 

 caused a variation of from thirty to forty degrees 

 of the galvanometer needle. From experiments 

 with this instrument, he demonstrated that animal 

 nerves and muscles are electroscopes of the most 



1 Carpenter's Physiology, p. 209. 



