THE SYMPATHETIC SYSTEM 307 



1. Substances acting on all the components of the 

 vegetative system. 



2. Substances acting only on certain components. 



The first group does not deserve much study; the 

 second, however, is worth while explaining. 



Certain substances act only upon certain vegetative 

 nervous systems and what is remarkable is that this 

 electivity is copied practically exactly on the great niorpho^- 

 logical and physiological division of the systems into : 



Cranio pelvic system or parasy mpathetic ; 



Dorsal lumbar system or sympathetic. 



That is, there are, among the substances having a 

 partial action, certain ones which manifest themselves by 

 their action upon the parasympathetic and others upon 

 the sympathetic and this action will be equivalent, all 

 things being equal, to stimulation or paralysis of the 

 system as a whole. Finally, there are substances having 

 a partial action, products which do not act upon the total 

 system, but only one of its parts still however, respecting 

 the law of pharmacological electivity. 



III. OUR IDEA OF PHARMACOLOGICAL, TONUS. 



If one of the systems of vegetative life is stimulated, 

 this stimulation will manifest itself in the parts enervated 

 by this system. There will be hypertonia of this system. 

 If this system is in a state of paralysis or inhibition, there 

 will be hypotonia of this system. From this, two major 

 ideas are brought to the front: hypertonia and hypotonia 

 of the vegetative nervous systems. 



So far there is nothing very complicated to this: it is 

 easy to understand that in the physiological, as well as 

 the pathological state, substances, be they endogenous or 

 exogenous, can produce in healthy or sick subjects, 

 phenomena equivalent to stimulation of a whole or part 



