310 ENDOCRINE GLANDS 



territories having both systems antagonistic to each other, 

 hypotonia of one system will manifest itself as a hyper- 

 tonia of the other. 



This being understood, it will be easy to divide the tonus 

 of the nervous systems of vegetative life. The classifica- 

 tion is as follows: 



1. If the two systems are acted upon at the same time 

 there will be: 



hyper \ ( hyper 



[ general tonus or ] neurotonia 



hypo J 



2. If one of the systems alone is affected there will be : 



hyper ] ( sympathetic or sympathicotonia 



Tonus of 

 hypo J I parasympathetic or parasympathicotonia. 



In the following chapter will be given a clinical descrip- 

 tion of the sympathicotonia and parasympathico- 

 tonia svndrome. 



V. THE SUBSTANCES ACTING UPON THE NERVOUS 

 SYSTEMS OF THE VEGETATIVE LIFE. 



These substances are :1. Exogenous, or 2. Endogenous. 



The exogenous products are: drugs or poisons. Their 

 number is only limited because of the paucity of 

 our knowledge. 



The endogenous products belong to two groups : 



1. Products resulting from the secretions of the endo- 

 crine glands, the hormones. 



2. Products resulting from the normal or pathological 

 function of various organs of the body. 



As far as the hormones are concerned, there is consider- 

 able to be said, but our knowledge of these products is 

 increasing daily, so that conclusions which are reached 

 to-day may have to be modified to-morrow. If we study 



