FOOD AND DRINK 95 



7. Renovation of the- Body. By this process, so far as 

 weight is concerned, the body might be renewed every twenty- 

 four days ; but these pounds of food are not all real nutriment. 

 A considerable portion of that which we eat is innutritions, 

 and though useful in various ways, is not destined to repair 

 the losses of the system. An opinion has prevailed that the 

 body is renewed throughout once in seven years ; how correct 

 this may be, it is not easy to decide, but probably the reno- 

 vation of the body takes place in a much shorter period. 

 Some parts are very frequently renewed, the nutritive fluids 

 changing more or less completely several times during the day. 

 The muscles, and other parts in frequent exercise, change 

 often during a year; the bones not so often, and the enamel 

 of the teeth probably never changes after being once fully 

 formed. (Read Note 5.) 



8. Mixed Diet. The habits of different nations in respect 

 to diet exhibit the widest and strangest diversity. The civil- 

 ized cook their food, while savages often eat it in a raw state. 

 Some prefer it when fresh ; others allow it to remain until it 

 has become tainted with decay. Those dwelling in the far 



of the dry food we take will exceed that given above ; chiefly for the 

 reason that they do not come to us pure and unmixed with fibrous 

 material and gelatine, whose use in nourishing the body is limited and 

 uncertain." Kensington Museum Hand-Book on Food. 



5. The Renewal of the Body. "To meet these constant chemical 

 changes, material is taken in, in the form of food and drink, Which is 

 being constantly assimilated, and so nutrition and repair are conducted. 

 The rapidity with which these changes are carried on is much greater 

 than is usually supposed. Paley, in his 'Natural Theology,' states that 

 seven years are requisite for the perfect renewal of the body ; and this 

 statement, owing partly to the mysticism associated with the number 7, 

 is generally accepted and believed. The time really is rather months 

 than years ; but it is absurd to fix a time which must necessarily vary in 

 different individuals, being much less in the infant than in the aged, in 

 the active than the indolent; widely different, too, in various tissues, 

 from the epithelium lining of the glands of the stomach, renewed several 

 times in each act of digestion, to the enamel of the tooth, which is proba- 

 bly never renewed during a lifetime." 



7. How often, then, might the body be renewed ? Why is it not ? Opinion ? How 

 correct ? What further is stated ? 



8. Habits of nations ? Give the different cases. 



