REPORT OF THIRTEENTH ANNUAL MEETING. 15 
he 
anatomical science, yet in their aggregate they present an indi- 
gestible mass of confused and meaningless detail, crude fact, well 
spiced with error, for the most part not worth the prodigeous 
labor of digging it out of the oblivion of classic tomes of by-gone 
anatomists. 
I do not mean to imply that all the problems of cranial nerve 
morphology are now cleared up; but I do claim that there is no 
longer any necessity for the further accumulation of uncritical 
and meaningless fact in this field of research. We have already 
gone far enough to point the way toward certain lines of fruitful 
correlation. We can not only correlate structure with structure, 
but we can interpret structure by function and thus bring out a 
fuller meaning. We are at least coming into a realization of 
the fact that we cannot fully understand any structure until we 
know what it can do. 
This point of view of course is not new, but as worked out 
practically in the peripheral nervous system it is exerting a 
elarifying influence upon our knowledge of the central system 
also. The present demand in cerebral anatomy is for conduction 
paths, for functional systems of neurones, and precise knowledge 
of the pathways between the brain and the periphery is the first 
step in such a central analysis. 
The primary function of the nervous system is to facilitate 
the reaction of the organism to the external forces of the environ- 
ment. Later, as the reacting mechanism becomes more com- 
plicated, the nervous system assumes the function of co-ordinat- 
ing this mechanism, 7. e¢., of reaction to the forces of the internal 
environment. These two functions lie at the basis of our most 
fundamental division of the analysis of the nervous system, viz.: 
(1) the somatic systems (sensory and motor) for bodily responses 
to external stimuli, and (2) the visceral systems (sensory and 
motor) for visceral reactions to internal stimuli. 
Each of these great divisions has been analyzed peripherally, 
more or less imperfectly as yet, into systems of components, as 
suggested above. Every such system of nerve fibers performs a 
separate function, conducts a single type of nervous impulse, either 
afferent, 7. e., sensory, or efferent, 7. e., excito-motor, excito-gland- 
ular, etc. The following systems are already distinguishable 
anatomically : 
