6 PHYSIOLOGY OF ALIMENTATION. 



of fowls. It requires nine to twelve seconds for a bolus of 

 solid food to reach the stomach, and a somewhat shorter time 

 for liquids to make the same journey. The reason for this 

 difference lies in the fact that liquids move somewhat more 

 rapidly in the upper portion of the oesophagus than do semi- 

 solids. In the lower portion of the oesophagus the rate for 

 both kinds of food is approximately the same. For all kinds 

 of food the rate of movement in the upper half of the oesoph- 

 agus is somewhat greater than in the lower half. 



In the dog swallowing approximates the same act in the 

 human being. The total time for the descent of a bolus of 

 food in this animal is from four to five seconds. In the upper 

 portion of the oesophagus the movement is always more rapid 

 than in the lower, and when the swallowed mass>is liquid 

 this rapid movement continues deeper into the oesophagus 

 than when it is solid or semi-solid. No distinct pause occurs 

 when the bolus changes from its rapid rate to the slower one. 



In man liquids are propelled deep into the oesophagus at a 

 rate of several feet a second bj> the sudden and sharp con- 

 traction of the mylo-hyoid muscles. This confirms the obser- 

 vations of KRONECKER and MELTZER. According to CANXOX 

 and MOSER, however, solids and semi-solids are not swallowed 

 in the same way. From studies on a seven-year-old girl 

 who was given gelatine capsules filled with bismuth sub- 

 nitrate, or bread-and-milk mush mixed with the same salt, 

 they conclude that the movement of food of these con- 

 sistencies through the oesophagus is always accomplished by 

 peristalsis. Nor does the food in its passage through the 

 oesophagus stop before it enters the stomach, which KRO- 

 NECKER and MELTZER believed to be the case. Only the rate 

 of progressive movement changes Trom a more rapid one in 

 the upper oesophagus to a slower one lower down. 



4. The Movements of the Stomach. The movements of 

 the various portions of the alimentary tract from the oesoph- 

 agus to the rectum have been the object of research of 

 many investigators for many years. The pages of this 



