Then various portions of the hemispheres were slowly but
completely destroyed by rubbing them with pieces of gauze.
In some instances a hemisphere was destroyed by burning.
In no case was there more than a slight response of the centers governing
circulation and respiration, and no morphologic change was noted
in an histologic study of the brain-cells of the uninjured hemisphere.
The experiment was as completely negative as were the experiments
on the "spinal dog." Clinically I have confirmed these experimental
findings when I have explored the brains of conscious patients
with a probe to determine the presence of brain tumors.
Such explorations elicited neither pain nor any evidence of altered
physiologic functions. The brain, therefore, contains no mechanism--
no nociceptors--the direct stimulation of which can cause
a discharge of nervous energy in a self-defensive action.
That is to say, direct injury of the brain can cause no purposeful
nerve-muscular action, while direct injury of the finger does cause
purposeful nerve-muscular action. In like manner, the deeper portions
of the spinal region have been sheltered from trauma and they, too,
show but little power of causing a discharge of nervous energy
on receiving trauma. The various tissues and organs of the body
are differently endowed with injury receptors--the nociceptors
of Sherrington. The abdomen and chest when traumatized stand first
in their facility for causing the discharge of nervous energy, _i.
e_., THEY STAND FIRST IN SHOCK PRODUCTION. Then follow the extremities,
the neck, and the back. It is an interesting fact also that different
types of trauma elicit different responses as far as the consequent
discharge of energy is concerned.

Because it is such a commonplace observation, one scarcely realizes
the importance of the fact that clean-cut wounds inflicted