712 PHYSIOLOGY OF DIGESTION AND SECRETION. 



esophagus by a peristaltic movement of the musculature. The 

 circular muscles are constricted from above downward by an ad- 

 vancing muscular wave. The upper portion of the esopha- 

 gus contains cross-striated fibers indicating rapid contraction; 

 the lower end consists of plain muscle only, while the intermediate 

 portion is a mixture of the two varieties. Kronecker and Meltzer 

 believe that each of these segments contracts as a whole and in 

 orderly succession, but other observers, on the evidence furnished 

 by Roentgen-ray photographs, agree that there is no perceptible 

 pause in the downward movement of the wave of contraction. These 

 same movements occur in the swallowing of liquid or soft food, but 

 in such cases the peristaltic wave follows the actual descent of the 

 food. According to the observation of Kronecker and Meltzer, it 

 takes about 6 sec. for the peristaltic wave to reach the stomach, 

 and the passage of the food through the cardia takes place with 

 sufficient energy to give rise to a murmur that may be heard b}- 

 auscultating over this region. According to the observations 

 made by Hertz,* liquids or liquid foods are held up at the end 

 of the esophagus and pass slowly into the stomach through the 

 sphincter. He estimates that an interval of from 4.6 to 8.6 sec. 

 elapses before the swallowed bolus disappears into the stomach, 

 about one-half of this time being occupied by the passage to the 

 bottom of the esophagus and one-half in the transit through the 

 cardiac orifice of the stomach. 



Nervous Control of Deglutition. — The entire act of swallowing, 

 as has been said, is essentially a reflex act. Even the comparatively 

 simple wave of contraction that sweeps over the esophagus is due 

 to a reflex nervous stimulation, and is not a simple conduction of 

 contraction from one portion of the tube to another. This fact was 

 demonstrated by the experiments of Mosso,t who found that after 

 removal of an entire segment from the esophagus the peristaltic 

 wave passed in due time to the portion of the esophagus left on the 

 stomach side, in spite of the anatomical break. The same experi- 

 ment was performed successfully on rabbits by Kronecker and 

 Meltzer. Observation of the stomach end of the esophagus in this 

 animal showed that it went into contraction two seconds after the 

 beginning of a swallowing act whether the esophagus was intact or 

 ligated or completely divided by a transverse incision. A still 

 more striking proof of the same fact is the interesting case cited 

 by V. Mikulicz of a man in whom a portion of the esophagus 

 had been resected on account of a carcinoma. The lower end 

 of the esophagus was given a fistulous opening in the neck and 



* Hertz, "Guy's Hospital Reports," 61, 389, 1907. 

 t Moleschott's "Untersuchungen, " 1876, volume xi. 



