510 



ON THE PHYSIOLOGICAL ACTION OF CASCA BARK. 



From this experiment it appears that the excitability of the 

 peripheral terminations of the vagus-nerve is not increased by 

 casca. 



Action on the Vagus-roots. 



The slowness of the pulse which quickly follows the injection 

 of casca, and which we have already shown to be due to stimu- 

 lation of the vagus-roots, might be caused either {a) by stimu- 

 lation of the central end of the vagus by increased blood- 

 pressure in the nerve-centres, or (h) stimulation by the direct 

 action of the drug itself ; (c) it was also possible that without 

 actually irritating the vagus-roots the casca might increase 

 their sensibility to other stimuli, reflex or otherwise. 



Effect on Minimum Excitability of the Vagus-roots, 



Experiment XXXVIL— March 30. 



A cat, weight 4 lbs., was chloroformed. 

 A cannula was inserted into the trachea. 



„ „ left carotid. 



„ „ left saphena vein. 



The right vagus nerve was cut, and its central end placed in 

 a Von Basch's electrode. 



