ACTION OF GLOSSOPHARYNGEAL 203 



The same remarks apply with equal force to the other stimulations we 

 are about to examine. 



Fig. 160. — Alteration in Eespieation on Stimulation of the Superior Laryn- 

 geal Nerve: i, by Mechanical Irritation of the Larynx; ii, by Tetanisa- 

 tion of the nerve. rabbit. 



2. The glosso-pharyngeal. — We can show the effect of this nerve 

 on respiration, as in the previous case, by two modes of stimulation : 

 (i.) By making the animal swallow a little water, and (ii.) by electrical 

 excitation of the nerve. Fig. 161 gives the usual result of these 

 stimulations. In i the animal was made to swallow about 2 c.c. of 

 water placed in its pharynx. We see that inspiration is immediately 

 inhibited, and that a very gradual relaxation occurred. During this 

 time the animal was making rapid swallowing movements. Inn with 

 electrical stimulation we have a corresponding result. Breathing 

 was at once inhibited for the time of about three respirations, ami 

 then recommenced, at first with shallow, then with deepening 

 spirations. After stimulation ceased there are seen to be two altera- 

 tions in the curve, namely at a and b. These were synchronous with 

 two swallowings. It is seen that in each case swallowing commenced 

 in the middle of inspiration, which was then immediately inhibited, a 

 slight expiration followed, and then as the swallowing ended the in- 

 spiration was completed. 



3. Effect of section of the two vagi.— While the respiration is 

 being recorded, the one vagus is lifted up by the loop previously placed 

 round it and cut. After a short time the second is cut in a similar 



