the factor of anemia being thereby wholly excluded during the application
of the trauma and during the removal of a specimen of brain tissue
for histologic study. In each instance, morphologic changes
in the cells of all parts of the brain were found, but it required
much more trauma to produce brain-cell changes in animals whose
blood-pressure was kept at the normal level than in the animals
whose blood-pressure was allowed to take a downward course.
In the cortex and in the cerebellum, the changes in the brain-cells
were in every instance more marked than in the medulla.

There is also strong NEGATIVE evidence that traumatic impulses
are not excluded by ether anesthesia from the part of the brain
that is apparently asleep. This evidence is as follows:
If the factor of fear be excluded, and if in addition the traumatic
impulses be prevented from reaching the brain by cocain[*] blocking,
then, despite the intensity or the duration of the trauma within
the zone so blocked, there follows no exhaustion after the effect
of the anesthetic disappears, and no morphologic changes are noted
in the brain-cells.


[*] Since the presentation of this paper, novocain has been
substituted for cocain in operations under anoci-association.


Still further negative evidence that inhalation anesthesia offers
little or no protection to the brain-cells against trauma is derived
from the following experiment: A dog whose spinal cord had been
divided at the level of the first dorsal segment, and which had
then been kept in good condition for two months, showed a recovery