316 ENDOCRINE GLANDS 



individual by the injections of chemicals having a selective 

 action on one or the other nerve. 



Suprarenalin injected subcutaneously in 1 gram doses 

 will cause a stimulation of the sympathetic system in 

 certain individuals. This will manifest itself by dilatation 

 of the pupil, a glycosuria superior to 5 grams per 24 hours, 

 after the injection of 100 grams of glucose in the morning, 

 will cause a polyuria, a tachycardia and an increase in the 

 blood pressure by vaso constriction. In other individuals 

 this dose will not cause any changes. 



Atropin and pilocarpin have an elective action on the 

 vagus. The first paralyses, while the second stimulates 

 the vagus. The injection of .001 gram of atropin sub- 

 cutaneously will, in certain individuals bring about a 

 marked reaction. This will manifest itself by a tachy- 

 cardia, a rapid dilatation of the pupils and dryness of the 

 mouth, due to stoppage of secretions. 



The same applies to pilocarpin. In some individuals it 

 will cause abundant salivation, sweating and an increase 

 in intestinal peristalsis. 



These differences in susceptibility are due to differences 

 in tonus of the two systems. The latent disequilibrium is 

 emphasized by the preceding reactions to the drugs. In 

 some we can see the predominance of the vagus; these are 

 the vago-tonics, in others we see the predominance of the 

 sympathetic; these are the sympathicotonic. 



Thus by means of pharmacological tests, we can explore 

 the vegetative nervous systems and can determine which 

 of the patients' symptoms are due to the vagus and 

 which are due to the sympathetic. 



The excitability of the vagus and the sympathetic can 

 also be brought out by mechanical means. By that we 



