GROWTH AND NUTRITION 



75 



each rat receiving one daily apart from the rest of the food. 

 Such a ration contained at most an exceedingly small quantity 

 of fat, but yet permitted the rats to attain normal mature 

 weights. 



Needless to say, these views as to the non-necessity of fat in 

 the diet do not indicate that it is also undesirable. Fats are a 

 valuable source of energy, and are useful reagents in the hands 

 of a skilful cook. 



Figure 48. Growth on diets almost entirely free from pre- 

 formed carbohydrate. After Osborne and Mendel. Courtesy 

 of the National Academy of Sciences. 



The Carbohydrates. Since there is doubt as to the need of 

 fat in the dietary, we may also raise the question, Is carbohy- 

 drate an essential constituent of the diet? Some theoretical con- 

 siderations might lead us to believe that carbohydrate is an in- 

 dispensable dietary component. According to generally current 

 physiological teaching, fats burn in the flame of carbohydrates, 

 and if the supply of available carbohydrate is deficient, fats 

 will not be completely oxidized and so acidosis may result. It 

 is, however, well known that carbohydrates may be derived from 

 proteins in normal metabolism, so it is possible that preformed 



