IS 



GERMINATION 



throughout the whole, each molecule giving out its elec- 

 tricities to those next it, which, throwing out the opposite 

 electricities, produce quiescence throughout. A constant 

 series of such polarisations and discharges, taking place 

 with enormous rapidity, constitute a current. 



The physiological argument against this theory is that 

 the rate of propagation of the nerve impulse is only 120 

 metres per second, against, roughly, the 3,000 miles of 

 electricity. But the argument does not hold good, because 

 the nerve impulse is not propagated along a homogeneous 

 wire but a long nerve which is anatomatically, though not 

 functionally, interrupted by thousands of synaptic junctions 

 and arborisations, at each of which the current suffers 

 delay. 



I will endeavour to make this clear as it is a very important 

 point. A condenser, as used in telegraphy, consists of a 

 number of sheets of tin or silver foil separated from each 

 other by a non-conducting substance, such as paraffin wax. 

 Now tension (electrical pressure) is in the inverse ratio to 

 the area over which a charge is distributed. Condensers are 

 conventionally shown thus : 



/7/yfe'/. ^^ f//7TO/. 



^i^s m 



. /hraff//? ii/<7X 



If we connect that apparatus in circuit with a battery : 



^'^r/h y 



.far/h 



the plate (tin foil) a will receive positive charge from the 

 battery and transmit by induction a negative charge to 

 plate &. Suppose the latter to have twice the area of a 

 and it will become evident that a single impulse could not 

 charge 6 to the same potential as a. Not only is that so 



