LIFE: ITS ORIGIN AND NATURE 43 
mental Laws of Human Behavior” has this to 
say, regarding the nature of the nervous im¬ 
pulse : 
“It is highly probable that the conduction of 
the excitation is a process of a chemical nature. 
The substance of a neuron, consisting of highly 
unstable organic compounds, must be well 
adapted to the conduction of chemical changes. 
It is also well-known that the conduction of 
chemical changes frequently involves, as by¬ 
products, so to speak, electrical phenomena. 
.What happens is this: A stream of ele¬ 
mentary substance flows—or, whatever it may 
actually do, is imagined to flow—from one end 
of the conductor to the other, and this flow 
or wandering of molecules or “ions,” as it is 
usually called, is accompanied by an electrical 
phenomenon. We are, then, probably justified 
in regarding the conduction of an excitation 
through a neuron as, not identical with, but at 
least analogous to, the wandering of ions 
through a conducting fluid—the electrolyte, to 
use the technical term—of a storage battery.” 
The fact that the nervous current is probably 
chemical in nature does not, however, help us 
to understand the nature of the changes which 
occur within the various nerve-cells of the body, 
—since these changes are, apparently, rational 
or teleological in their action. Especially we are 
no nearer an interpretation of the nature of the 
activities going on within the cerebrum, with 
which thought and consciousness are undoubt¬ 
edly associated. The structure of the human 
brain is incredibly complicated, and the number 
of inter-acting nerve cells is indeed extraor- 
