DIGESTION. 173 



tenth of a second. The inference was that the water was projected 

 or shot down the pharynx and esophagus in this period of time, and 

 in its passage compressed both balloons practically at the same in- 

 stant. The same was found to be true when small masses of more 

 consistent food were swallowed. 



The curves of the entire deglutitive act recorded by the two levers 

 are, however, different in form. (See Fig. 69.) The pharyngeal curve, 

 i, presents two crests, the first, A, being due to the compression caused 

 by the passage of the bolus, the second, B, due to the compression 

 exerted by the contraction of the pharyngeal muscles. The interval 

 of time between these two crests amounts to not more than 0.3 

 second. In the esophageal curve, 3, the elevation, C, corresponds 

 to the elevation, A, and is likewise due to the compression exerted 



FIG. 69. TRACING OF THE ACT OF DEGLUTITION, i. A indicates the compression of 

 the elastic bag caused by the bolus projected by the contraction of the mylohyoid 

 muscles. B. Contraction of the pharynx. 2. Line marking seconds. 3. Trac- 

 ing of the bag in the esophagus 12 cm. from the teeth. C. Compression of the 

 bag by the bolus corresponding to A. D. Compression by the residues of the 

 bolus carried on by the contraction of the pharynx, B. E. Contraction of the 

 esophagus. 



by the bolus. The interval of time between the beginning of the 

 first and second curves was not more than o.i second, regardless of 

 the depth to which the esophageal balloon was plunged. At a later 

 period a second rise of the lever was recorded ; the time of its appear- 

 ance, height, duration, etc., were found to increase with the depth of 

 the balloon. 



These facts demonstrate that deglutition consists of two phases: 

 (i) a rapid rise of pressure in the pharynx, as a result of which the 

 bolus is suddenly shot down to the stomach; (2) a peristaltic con- 

 traction of the musculature of the canal, which, acting as a supple- 

 mentary force, carries onward any particles of food in the canal and 

 forces the bolus through the closed sphincter at the end of the esoph- 

 agus. 



