FACTS 183 



importance of these direct protoplasmic communications 

 capable of making felt at once, in one point of the living 

 being, a rupture of equilibrium produced at another distant 

 point of the same individual. This transforms the individual 

 as a whole into a unified mechanism wherein nothing that 

 takes place in one part is indifferent to the other regions 

 of the organism. 



Neuron is the name given to a cellular element provided 

 with a considerable protoplasmic prolongation which puts 

 it in relation with remote cells of the body. This proto- 

 plasmic prolongation (cylindraxis) is of a very peculiar 

 structure making it especially fit for the rapid transmission 

 of ruptures of colloid equilibrium. According to the law 

 of functional assimilation, it is natural that this cylindraxis, 

 whose function it is to transmit, should acquire the char- 

 acter transmitter in the highest degree. 



The cell which possesses this greatly lengthened cylin- 

 draxis has also other protoplasmic prolongations less differ- 

 entiated ; they form what are called the hairs of the neuron. 

 In Fig. 14 we see the example of a neuron whose cylindraxis 

 loses itself, by prolonged ramifications, in the protoplasmic 

 substance of an epithelial element belonging to the external 

 surface of the individual. 



Let some phenomenon of the environment (of light or 

 sound, colloidal or chemical) be able to make an impression 

 on the protoplasm of the epithelial element and determine 

 in it a rupture of the colloid equilibrium. This rupture 

 of equilibrium will be transmitted from point to point 

 by the cylindraxis to the body of the neuron, in which it will 

 branch out in every direction according to the conditions 

 of colloid equilibrium then existing in it. 



The name of nervous influx is given to this protoplasmic 

 transmission of a rupture of colloid equilibrium. It has 



