14 OHIO STATE ACADEMY OF SCIENCE. 
PRESIDENT’S ADDRESS. 
THE DOCTRINE OF NERVE COMPONENTS AND SOME 
OPTS APPLICATIONS. 
By C. Jupson HERRICK. 
The original purpose of the students of nerve components 
was the analysis of the peripheral nervous system into units which 
should have at the same time a functional and a structural signifi- 
cance. This obviously is not the case with the cranial and spinal 
nerves as commonly enumerated. The structural peculiarities 
of each of the twelve pairs of cranial nerves, for instance, while 
fairly well defined in the human body, are very diverse in the 
vertebrate series as a whole. Thus the facial nerve from being 
predominantly sensory in lower vertebrates (more than half of its 
fibers in fishes belonging to a sensory system not represented at 
all in mammals) becomes in man predominantly motor with only 
a vestigeal remnant of the sensory components, and even the 
motor component innervates chiefly muscles new to the mammalia. 
We might multiply illustrations of the structural instability of the 
cranial nerves. And that the cranial nerves have any special sig- 
nificance as functional units cannot be maintained for a moment, 
no two pairs in the human body having even approximately the 
same function. 
But the first measurably complete analysis of the cranial 
nerves into their components for their entire extent showed at 
once the presence of certain structural and functional systems of 
components, the laws of whose distribution have apparently little 
to do with the serial order of the cranial nerves as commonly 
enumerated. 
We have, then, a number of systems of components each 
of which is defined structurally by similarity of peripheral and 
central terminal relations, and functionally by the transmission of 
nervous impulses of the same type or modality. Among these 
systems are tactile, auditory, visual, olfactory, motor, gustatory, 
etc., each with very characteristic terminal relations. 
Now, this structure is absolutely meaningless apart from 
its function. Let any one who doubts this spend a few months 
(as I have done) in trying to master and correlate the existing 
literature of the cranial nerves of vertebrates. Though these 
descriptions were for the most part written by famous masters of 
