6 GENERAL SCIENCE 



A child who habitually breathes through the mouth may 

 be afflicted with adenoids, and their removal may become 

 necessary. Catarrh is a persistent congested condition of 

 the mucous lining of the nasal cavity, and may cause 

 deafness. 



The thorough mastication and insalivation of food is an 

 essential stage in the process of dissolving it. This process is 

 known as digestion. Water or other drinks used to wash 

 down the food do not take the place of the saliva. Man, 

 unlike birds and domestic fowls, has no gizzard to do what 

 the teeth should have done. 



The saliva contains small portions of a so-called digestive 

 ferment which brings about chemical changes in starchy foods, 

 converting the starch into a form of sugar which dissolves 

 easily. The other digestive fluids also cause chemical 

 changes in foods through the action of the ferments which 

 they contain. A nervous or excited state, or extreme 

 weariness in body or mind, interferes with and may stop the 

 secretion of these digestive fluids 1 , thus impairing digestion. 

 One should not eat at such times, but wait until rested and 

 quieted. A happy frame of mind favors digestive processes. 

 Mealtime should be a time of mirth and social enjoyment, 

 and never a time for controversy and settlement of disputes, 

 or for administering family discipline. The sight, smell, 

 and taste of appetizing food, and a state of unsatisfied 

 hunger, maintains the flow of the digestive fluids. The 

 flow lessens when these conditions cease to exist. Many 

 people attempting to speak in public experience difficulty 

 from dry lips and mouth. Their nervousness causes a less- 

 ened flow of saliva. 



A dry fevered appearance of the tongue and mouth, and 

 a heavy white or yellowish coating of the tongue, indicate 



1 The amount of gastric juice secreted per day may be five pints or more. 



