of the spinal reflexes, such as the scratch reflex, etc. Such an
animal is known as a "spinal dog." Now, in this animal, the abdomen
and hind extremities had no direct nerve connection with the brain.
In this dog, continuous severe trauma of the abdominal viscera and of
the hind extremities lasting for four

hours was accompanied
by but slight change in either the circulation or in the respiration,
and by no microscopic alteration of the brain-cells (Fig. 1). Judging
from a large number of experiments on NORMAL dogs under ether,
such an amount of trauma would have caused not only complete
physiologic exhaustion of the brain, but also morphologic alterations
of all of the brain-cells and the physical destruction of many
(Fig. 2). We must, therefore, conclude that, although ether anesthesia
produces unconsciousness, it APPARENTLY PROTECTS NONE OF THE BRAIN-CELLS
against exhaustion from the trauma of surgical operations; ether is,
so to speak, but a veneer. Under nitrous oxid anesthesia there is
approximately only one-fourth as much exhaustion as is produced by equal
trauma under ether (Fig. 3). We must conclude, therefore, either that
nitrous oxid protects the brain-cells against trauma or that ether
predisposes the brain-cells to exhaustion as a result of trauma.
With these premises let us now inquire into the cause of this
exhaustion of the brain-cells.


The Cause of the Exhaustion of the Brain-cells as a Result of Trauma
of Various Parts of the Body under Inhalation Anesthesia


Numerous experiments on animals to determine the effect of ether
anesthesia _per se_, _i. e_., ether anesthesia without trauma,
showed that, although certain changes were produced, these included