ACID AND ALKALINE STATES. 221 



voltaic battery, are found ; and where these exist 

 voltaic electricity will be produced. 



Professor Pepper says T " that it is a remarka- 

 ble fact that when an acid and alkaline solution 

 are so placed that their union may be effected 

 through the substance of an animal membrane, 

 or indeed any porous diaphragm, a current of 

 electricity is evolved. Now, with the exception 

 of the stomach and caecum, the whole extent of 

 the mucous membrane is, in the human subject, 

 bathed with an alkaline mucous fluid, and the 

 external covering of the body the skin 

 is as constantly exhaling an acid fluid. The 

 mass of the animal frame is thus placed be- 

 tween the two great envelopes, the one alkaline 

 and the other acid, meeting only at the external 

 outlets. This arrangement has been shown by 

 Donne to be quite competent to the evolution 

 of electricity." 



Electric currents are vibrations moving with 

 increased velocity, being more or less rapid as 

 the velocity is accelerated or retarded. Vibra- 

 tions caused by electric excitation may increase 

 in velocity to a current, and a current decrease 

 in velocity to vibrations and to a state of equi- 

 librium. 



In the systemic circulation, the blood is trans- 

 mitted by the periodic contraction through the 

 whole vascular system. It is conveyed from the 



1 Cyclopaedic Science, p. 287. 



