DIGESTION 161 



sensation in the stomach following the swallowing of a mouthful of cold water 

 occurred too quickly to be explained by the prevalent belief that its transfer- 

 ence was caused by ordinary peristalsis, the rate of progression of which was 

 known to be slow. Falk then discovered the fact, by introducing through the 

 mouth into the pharynx a tube connectedexternally with a water manome- 

 ter, that during the act of swallowing there is a sudden rise of pressure 

 equal to about twenty centimeters of water. 



These experiments demonstrated that at the beginning of deglutition 

 there is a sudden rise of pressure, the result of a quickly acting force resident 

 in the mouth or pharynx, in consequence of which the liquid foods are 

 rapidly thrown down toward the end of the esophagus, peristalsis playing 

 no part in the process. The proof, however, of these statements was fur- 

 nished by Meltzer. This observer introduced into the pharynx and esophagus 

 rubber tubes, the ends of which were provided with thin-walled rubber bal- 

 loons which could be distended with air. The outer ends of the tubes were 

 connected with Marey's recording tambours. Any compression of the bal- 

 loon would be followed by the passage of the air into the tambour and an 

 elevation of the lever. With one balloon in the pharynx and the other in 

 the esophagus at varying depths, and the recording levers of the tambours 



FIG. 67. 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. 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.) 



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. 67.) The pharyngeal curve, i, 

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



