364 BIOLOGICAL PHYSICS 



This doctrine of neural duality, is by no means new, 

 the division of the nervous system into systemic, and 

 sympathetic, having been acknowledged for a somewhat 

 long period by, anatomists, physiologists, and clinicians 

 alike, in their treatment of the great subject of the 

 nervous system. Anatomically regarded, the duality of 

 the nervous system seems more apparent, than real ; 

 nevertheless, a well-marked individuality characterises the 

 respective structures of the brain, cord, and nerves, of 

 its systemic division, and the ganglionic developments, 

 and connecting nervature, of its sympathetic division, 

 which becomes more and more apparent, when subjected 

 to physiological observation, and clinical experience, sup- 

 plemented by pathological research. By the light shed 

 from these various quarters, and focussed on discernment 

 of this individuality, and duality, of structure, and func- 

 tion, we perceive that the systemic nervous system is 

 related to the so-called non-nervous structures alone, 

 which are concerned with the daily recurring volitional, 

 and intellectual, necessities of life, and that the sympa- 

 thetic nervous system, so called, is related to the non- 

 nervous structures, and the passive, organic, or forma- 

 tive, functions, displayed in varying manner, and degree, 

 throughout the entire chain of living creatures, vegetable, 

 and animal, alike. The systemic nervous system displays 

 its activity rhythmically, or by " fits and starts," according 

 to, and synchronising mainly with, the earth's diurnal 

 motion, the intervals of rest being utilised to repair 

 waste, and renew energy, while the sympathetic displays 

 a constant, if faintly intermittent, functional activity, in 

 maintaining the continuity of organic molecular change, 

 and exchange the former, or systemic, acting only during 

 periods of consciousness, while the latter, or sympathetic, 

 acts continuously from the beginning to the end of the 

 individual life, thus realising, in the economy of healthy 

 organic life, the harmonious working of a dual organism, 

 on the lines of the oft-quoted political parallel, or institu- 

 tion, an imperium in imperio. 



Pathologically, the harmony, and success, of the 

 working of this dual nerve economy is liable to dis- 

 turbance in numberless ways, and to numberless degrees 



