102 BUMAN BIOLOGY 



of jaundice. The liver, in the second place, serves as a great store- 

 house for the carbohydrates when the blood does not need them for 

 immediate use. When, on the other hand, there is a lack of carbo- 

 hydrates in the blood, some of the supply in the liver is taken up 

 again by the blood. Finally, the liver helps to destroy some of the 

 worn out cells of the blood (the red corpuscles), and the waste 

 materials thus formed are passed off into the intestine as a part of 

 the bile. 



IX. Hygiene of Digestion 



144. Hygienic habits of eating. — One should form the 

 habit of eating slowly and of thoroughly masticating each 

 mouthful of food. For by this process the food is thoroughly 

 broken up, and thus is prepared for rapid digestion not only 

 in the stomach but in the intestines as well. The process 

 of chewing likewise stimulates the flow of saliva. Saliva 

 not only helps digest food in the mouth, but this juice also, 

 when swallowed with the food, continues for a time the di- 

 gestion of starch in the stomach and likewise stimulates to 

 greater activity the glands in the walls of the stomach. 



At least a half hour should be devoted to the eating of 

 dinner and twenty minutes to breakfast, lunch, or supper. 

 The proper digestion of food depends in no small degree upon 

 one's mental state; worry and disagreeable topics should, 

 therefore, be forgotten as far as possible while one is eating, 

 and the mealtime should be made a season of enjoyment. 

 Regular hours of eating are of great importance, for nothing 

 more commonly deranges the digestive system than the con- 

 tinual nibbling of food or sweetmeats between meals. One 

 should refrain from vigorous exercise or mental exertion for 

 some time after eating ; the reason for this will be clear after 

 a study of the blood system. 



145. Prevention of disease. — To insure a state of health 

 the useless residue of the food should be expelled from the 



