84 



EXEKCISE XIII 



carefully the record of movements of respiration of chest-wall, and when 

 this is running regularly cut with a single snip of sharp scissors the right 

 vagus nerve in neck where exposed below the cricoid cartilage. Observe 

 that slower and ampler movement of ventilation of chest ensues. Observe 

 further effect on the record. Ligate central end of right vagus and faradize 



Text-fig. 31. Eespiratory movements of chest (bulbo-spinal preparation) 

 recorded by stethograph of text-fig. 30 (L. S. Laffitte). Inspiratory movements 

 upward ; expiratory movements followed by respiratory pause, t, time in seconds. 



mildly the central stump. Observe effect on the record ; with very weak 

 stimuli, short arrest of respiratory movement in the expiratory position ; 

 with stronger, a longer arrest in the inspiratory position, followed by 

 quickened rhythm. Cut the left vagus ; the respiratory rhythm becomes 

 still slower and deeper. Detach recording stethograph. Observe interior 

 of larynx. 



ANNOTATION 



Obs. 61. That even the first phase, the 

 linguo-faueial, of deglutition is essentially 

 a reflex act was pointed out first by Marshall 

 Hall, 1836 (Led. on the Nerv. System. 

 London). Alcock {Bubl. Jnl. of Med. 

 Science, vol. x, p. 260, 1836) and Magendie 

 {Leqons sur les fonctions du systeme nerveux, 



vol. ii, p. 293 ; Paris, 1889) showed a direct 

 afferent nerve for it to be glosso-pharyngeal. 



Ohs. 62. The difference in phagetic power 

 of various fluids was shown by F. R. Miller 

 and Sherrington {Quart. Jnl. of Eiperim. 

 Physiol, vol. ix, p. 157, 1915). 



Obs. 66. Longet [Traite de physiologic, 



