RESPIRATION. 



419 



central end of the divided superior laryngeal nerve be stimulated with 

 induced electric currents, the opposite effect is produced: viz., an excess of 

 the expiratory over the inspiratory movement until the chest-walls come to 

 rest in the condition of passive expiration. The superior laryngeal nerve 

 apparently contains fibers which gradually inhibit activity of the inspiratory 

 center and hence the inspiratory movement. 



mect.ob. 



FIG. 199. DIAGRAM SHOWING THE RELATION OF THE PULMONARY FIBERS OF THE VAGUS TO 

 THE INSPIRATORY CENTER AND THE CONNECTIONS OF THE LATTER WITH THE PHRENIC AND 

 INTERCOSTAL NERVE CENTERS AND THEIR RELATED MUSCLES. (G. Bachmari). med. ob. Medulla 

 oblongata. sp. c. Spinal cord. p. v. r. Pulmonary vagus nerve, excitator and inhibitor. iri*sp. c. 

 Inspiratory center, phr. c. Phrenic nerve centers, phr. n. Phrenic nerve, int. n. c. Intercostal 

 nerve centers, int. c. n. Intercostal nerves, ext. int. c. m. External intercostal muscles. 



The same result, an expiratory standstill, not infrequently follows strong 

 stimulation of the divided vagi, and always after the administration of 

 large doses of chloral. 



The results of these experiments would seem to indicate that the vagus 

 nerve contains two classes of nerve-fibers, one of which, when stimulated, 

 inhibits and regulates the discharge of nerve energy from the inspiratory 



