in DIGESTION IN THE MOUTH AND STOMACH 161 



curves then show a second elevation (about 1 sec. after the first), 

 which depends on the contraction of the constrictors of the 

 pharynx and oesophagus set up by the passage of the bolus. In 



B 



FIG. 54. Curves of deglutition as in Fig. 53. In A and B the oesophageal sound was passed 

 12 cm. beyond the opening of the oesophagus ; in C, 16 cm. Less water was swallowed at A 

 and C than in B. 



fact in the tracings of Fig. 54, in which the oesophageal sound 

 had been introduced farther into the oesophagus, the second rise 

 occurs much later than the first, which practically coincides 

 with the pharyngeal signal. 



The first signal indicates the rise of pressure in the gullet 



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