from muscular exertion (Figs. 2, 4, 5, and 13). For the present,
we shall assume that fear is a REPRESENTATION of trauma.
Because fear was created by trauma, fear causes a discharge of the energy
of the nervous system by the law of phylogenetic association.
The almost universal fear of snakes, of blood, and of death
and dead bodies may have such a phylogenetic origin.
It was previously stated that under the stimulus of fear animals
show preternatural strength. An analysis of the phenomena of fear
shows that, as far as can be determined, all the functions of the body
requiring the expenditure of energy, and which are of no direct
assistance in the effort toward self-preservation, are suspended.
In the voluntary expenditure of muscular energy, as in the chase,
the suspension of other functions is by no means so complete.
Fear and trauma may drain to the last dreg the dischargeable
nervous energy, and, therefore, the greatest possible exhaustion
may be produced by fear and trauma.


Summation

In the discharge of energy, summation plays an important role.
Summation is attained by the repetition of stimuli at such a rate
that each succeeding stimulus is applied before the nerve-cells
have returned to the resting stage from the preceding stimulus.
If drops of water fall upon the skin from a sufficient height to cause
the slightest unpleasant sensation, and at such a rate that before
the effect of the stimulus of one drop has passed another drop
falls in precisely the same spot, there will be felt a gradually
increasing painful sensation which finally becomes unbearable.
This is summation of stimuli. When, for a long time, a patient