FOOD UNITS 183 



has been proved experimentally to be equivalent 

 to about ^\ Ibs. of either of them. But it is not so 

 easy to reduce protein to its carbohydrate equiva- 

 lent, for its function is to repair the waste of the 

 working parts of the body, whilst fats, carbohy- 

 drates and fibre act as fuel. It is indeed impos- 

 sible to compare the value of protein with that of 

 other nutrients on a scientific basis, for the func- 

 tion of protein is quite distinct. But for the pur- 

 pose of comparing values on the market, protein 

 may be reduced to its carbohydrate equivalent on 

 a money basis, when it is found that the average 

 price of I Ib. of protein is 2^ times as much as the 

 average price of I Ib. of carbohydrate. By adding 

 together the percentages of protein and fat, multi- 

 plying the sum by 2^, and then adding to the 

 result the percentages of digestible carbohydrate 

 and fibre, a figure is obtained which represents the 

 amount of carbohydrates equivalent in money 

 value to the whole of the nutrients of the feeding 

 stuff. Taking as the unit for this purpose one- 

 hundredth of a ton of carbohydrates, the figure 

 represents the number of food units equivalent to 

 all the digestible nutrients in a ton of the food. 

 The cost per food unit can then be calculated 

 simply by dividing the price per ton by the num- 

 ber of food units. In this manner the cost per 

 food unit of all the feeding stuffs included in the 

 quotations has been calculated, and is given in 

 Table II. The cost per food unit varies from 



