DIGESTION. 159 



lever. With one balloon in the pharynx and the other in the esophagus at 

 varying depths, and the recording levers of the tambours applied against 

 the surface of a revolving cylinder, it became possible, with the addition of a 

 chronograph, to obtain a graphic representation of the time relations of 

 simultaneous and successive compressions of the two balloons. 



It was found as the result of many experiments that no matter how deep 

 the position of the esophageal balloon, it was compressed almost simultane- 

 ously with the pharyngeal balloon, as shown by the rise of the levers on 

 swallowing a mouthful of water. The interval of time between the rise of 

 the two levers did not amount to more than the 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 instant. 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, 



FIG. 69. TEACING 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. Con- 

 traction of the pharynx. 2. Line marking seconds. 3. Tracing of the bag in the esophagus 

 12 cm. from the teeth. C. Compression of the bag by the bolus corresponding to A. D. Com- 

 pression by the residues of the bolus carried on by the contraction of the pharynx, B. E. Contrac- 

 tion of the esophagus. (Landois and Stirling.} 



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 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 sud- 

 denly shot down to the lower end of the esophagus; (2) a peristaltic contrac- 

 tion of the musculature of the canal, which, acting as a supplementary force, 

 carries onward any particles of food in the canal and forces the bolus through 

 the closed sphincter cardia at the end of the esophagus. 



