REPORT OF THIRTEENTH ANNUAL MEETING. I5 



anatomical science, _vet in their aggregate they present an indi- 

 gestible mass of confnsed 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 realiza'tion 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 

 clarifying 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, i 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 peripherallv. 

 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, i. c, sensory, or efferent, i. e., excito-motor, excito-gland- 

 ular, etc. The following systems are already distinguishable 

 anatomically : 



