THE SYMPATHETIC SYSTEM 315 



(c) Of the abdominal sympathetic; 



(d) Of the peripheral sympathetic. 



They constitute the segmentary pathology of the greater 

 sympathetic nerve. 



I. HYPEREXCITABILITY SYNDROME OF THE 

 VEGETATIVE NERVOUS SYSTEM. 



SYMPATHICOTONIA AND PARASYMPATHICOTONIA 

 OR VAGOTONIA. 



Morphological and physiological studies show that the 

 true sympathetic on one side, and the parasympathetic 

 system on the other, have fibres which, from a physio- 

 logical and pathological point of view, have a remarkable 

 antagonism to each other. Due to the antagonisms of 

 these two systems there results a state of equilibrium. 

 For instance, the heart normally beats at a rate of from 

 68 to 72 per minute, because the action of the sympa- 

 thetic counterbalances that of the vagus ; in the same man- 

 ner the action of the pupil is regulated by the action of 

 the sympathetic (dilator) and the parasympathetic (3rd 

 cranial, constriction). 



The maintenance of this equilibrium results in the 

 physiological state. Disturbance in equilibrium results 

 in a pathological state. The variation may be in either 

 one of the two systems as a hypo or a hyperactivity. We 

 can, therefore, conceive of pathological disturbances due 

 to hypo or to hypersympathiconia, and again to hypo or 

 hyperparasympathicotonia. 



Eppinger and Hess showed a few years ago that it was 

 possible to determine which of the two systems was 

 preponderant, by studying the reactions produced in an 



