METABOLISM AND FOOD 91 



husked grains (oats, barley) and the leguminous 

 seeds have a less value on account of the husks and 

 chaff. All those by-products from which the 

 inner nutritious portion of the grain has been with- 

 drawn by grinding or mashing, e.g. brans, barley 

 refuse, brewers' grains, slumps, etc., have proved to 

 be of low value. 



Amongst potatoes, turnips, and similar foods, 

 the former have proved to be of full value, whereas 

 mangels and their by-products are not. The 

 digestible nutrients in the different food-stuffs 

 therefore differ considerably in value. If attention 

 is not paid to this important fact and the rations 

 are calculated as formerly on the amount of digest- 

 ible material which they contain, very serious 

 errors can be made. In view of what has just been 

 said, it is absolutely necessary that the value of the 

 nutrients should enter into the calculation. This 

 is done most suitably and easily if the amount of 

 full-value nutrients which the food-stuff contains 

 is reckoned with the help of the " value " number. 

 If, however, such a calculation were to be made 

 for each group of nutrients, a clear estimate of the 

 productive value of many feeding-stuffs would not 

 be obtained, quite apart from the labour of such a 

 procedure. The writer therefore considers it best 

 to express the fat-forming value of the feeding-stuffs 

 by a single number, and to use starch as a standard. 

 An example will make this clear. Suppose an 



