42 LIFE: ITS ORIGIN AND NATURE 
in the brain, and say “here occurs the sen¬ 
sation of sight,” or “this portion of the brain 
i 3 responsible for the movement of the toes 
on the left foot,” etc. Sensory or afferent nerv¬ 
ous impulses carry sensations from the surface 
of the body to certain centers, and here a 
change of some sort takes place, which oc¬ 
cupies an appreciable time, and which is anal- 
agous to conscious deliberation on the part of 
that nerve center, as though deciding what to 
do. A motor or efferent nervous impulse is 
then sent forth, causing a specific movement, 
representing a reaction to the stimulus in ques¬ 
tion. 
What is the nature of this nervous impulse? 
The general structure of the nervous system 
being so similar to an electric relay system, it 
has been contended, very naturally, that the 
nature of the nervous impulse is electric in 
character. This idea, however, was afterward 
shown to be untrue for the simple reason that 
the rate of conduction was so very different. 
A nervous impulse travels along the fibre with 
a velocity of only about two hundred feet per 
second, while the velocity of light and elec¬ 
tricity, as we know, is slightly more than a 
hundred and eighty-six thousand miles per 
second. The two are, therefore, entirely dis¬ 
similar in character. If an elephant were to 
step upon a sharp object, it would take him 
an appreciable time to react, and lift his foot, 
whereas if the nervous current were electric in 
nature, this reaction ought to be practically in¬ 
stantaneous. 
Dr. Max Mayer, in his book “The Funda- 
