CHAP, ii.] 



RESPIRATION. 



477 



of carbonic acid produced and oxygen consumed in a given 

 period remaining after division of the nerves about the same as 

 when these were intact ; but it is undesirable to insist too much 

 on the exactness of this compensation. 



FIG. 92. EFFECT ON RESPIRATION OF SECTION OF BOTH VAGUS NERVES. 



The curve was obtained in the same way as Fig. 91. The second vagus nerve 

 was divided at x. 



When after division of both vagus nerves in the neck, the 

 medulla being intact, the central stump, that connected with 

 the central nervous system, of one of them is stimulated with a 

 gentle interrupted current, the effects are not always the same ; 

 one of two results may follow and that whichever of the two 

 nerves be used. In a certain number of cases, and these may 

 perhaps be regarded as the more typical ones, the respiration, 

 which from the division of the nerves had become slow, is 

 quickened again (Fig. 93) ; and with care, by a proper appli- 

 cation of the stimulus, the normal respiratory rhythm may for 



FIG. 93. QUICKENING OF RESPIRATION BY GENTLE STIMULATION OF THE 

 CENTRAL END OF THE VAGUS TRUNK. 



The curve was obtained in the same way as Figs. 91, 92. Stimulation of the 

 vagus began at x, and ended at y. 



