HUMAN PHYSIOLOGY 



CHAP. 



smelling, and even talking about foods makes 

 mouth water," especially when one is hungry. 



the 



1. Put into a test tube or small bottle a little boiled starch, a little 

 saliva, and about twice as much water. Shake it up well and heat it 

 just a little (not over 100 F.). After a few minutes add iodine and 

 notice that the color is not blue, showing that there is no starch 

 present What has changed the starch ? 



2. Repeat the experiment, taking raw starch. What is the in- 

 ference ? 



3. In place of iodine, add Fehling's solution, which may be 

 obtained at a drug store, and boil it for a moment. The precipita- 

 tion of copper shows that sugar is present. The starch has been 

 changed to sugar. 



71. Swallowing. After the food has been thor- 

 oughly chewed and moistened with saliva it is ready 



to go into the stom- 

 ach. The movement 

 through the pharynx 

 and oesophagus into 

 the stomach is called 

 swallowing or deglu- 

 tition. The food does 

 not fall through this 

 tube, because one can 

 swallow lying down 

 or even standing on 



his head. Did yOU 



Larynx 

 (Esophagus 



FIG. 43. The beginning of the food and air 

 passages (Zuppke). 



drinking from a pail on the ground ? The water goes 

 up into the stomach in this case. 



The tongue presses up against the hard palate and 



