The brain-cells have existed for eons and, amid the vicissitudes
of change, they have persisted with perhaps less alteration than has
the crust of the earth. Whether in man or in the lower animals,
they are related to and obey the same general biologic laws,
thus being bound to the entire past and performing their function
in accordance with the law of phylogenetic association.
For so long a time have we directed our attention to tumors,
infections, and injuries that we have not sufficiently considered
the vital force itself. We have viewed each anatomic and pathologic
part as an entity and man as an isolated phenomenon in nature.
May we not find in the laws of adaptation under natural selection,
and of phylogenetic association, the master key that will disclose
to us the explanation of many pathologic phenomena as they have
already explained many normal phenomena?
And may medicine not correlate the pathologic phenomena of the sick
man with the forces of evolution, as the naturalists have correlated
the phenomena of the sound man, and thus may not disease, as well
as health, be given its evolutionary setting?