ORGANS AND PROCESSES OF DIGESTION 165 



Frequency of Taking Food. Eating between meals is 

 manifestly an unhealthful practice. The question has 

 also been raised as to whether the common habit of eating 

 three times a day is best suited to all classes of people. 

 Many people of weak digestive organs have been bene- 

 fited by the plan of two meals a day, while others adopt 

 the plan of eating one heavy meal and two light ones. 

 Either plan gives the organs of digestion more time to 

 rest and diminishes the liability of overeating. On the 

 other hand, those doing heavy muscular work can hardly 

 derive the energy which they need from less than three 

 good meals a day. Though no definite rule can be laid 

 down, there is involved a hygienic principle which all 

 should follow : Meals should not overlap. The stomach 

 should be free from food taken at a previous meal before 

 more is introduced into it. When this principle is not 

 observed, material ferments in the stomach, causing indi- 

 gestion and other disorders. It should be noted, however, 

 that the overlapping may be due to overeating as well as 

 to eating too frequently. 



Dangers from Impure Food. Food is frequently the 

 carrier of disease germs and for this reason requires close 

 inspection (page 128). Typhoid fever, a most dangerous 

 disease, is usually contracted through either impure food or 

 impure water (Chapter XXIII). One safeguard against 

 disease germs, as stated above, is thorough cooking. Too 

 much care cannot be exercised with reference to the water 

 for drinking purposes. Water which is not perfectly clear, 

 which smells of decaying material, or which forms a sedi- 

 ment on standing is usually not fit to drink. It can, how- 

 ever, be rendered comparatively harmless by boiling. The 

 objections which many people have to drinking boiled 

 water are removed when it is boiled the day before it is 



