190 AN AGRICULTURAL WAR PROBLEM 



in the foods which it was proposed to use, and 

 the total nutritive value of the foods. The relative 

 proportion of protein was expressed by reducing 

 the fat to its carbohydrate equivalent as before 

 by multiplying the percentage of digestible fat 

 by 2^. The product was then added to the per- 

 centages of digestible carbohydrates and fibre, and 

 the sum divided by the percentage of digestible 

 protein. This gave the ratio of protein to fats, 

 carbohydrates and fibre all reduced to carbohy- 

 drate equivalent. It was stated in the form of 

 the ratio of I part of protein to so many parts of 

 non-protein food, and appears in Table IV (p. 199) 

 under the well-known name, nutritive ratio. In 

 replacing one food by another, or one mixture by 

 another, it is necessary to preserve approximately 

 the same nutritive ratio. For instance if it is 

 desired to replace a mixture of linseed cake and 

 cotton cake, which have become very expensive, by 

 ground nut cake, which is still comparatively cheap, 

 the ground nut cake must be, so to speak, diluted 

 with something with a wide nutritive ratio so that the 

 nutritive ratio of the mixture may be approximately 

 that of the mixture of linseed and cotton cakes. 



The question of total nutritive value is not quite 

 so simple. Many attempts have been made to re- 

 duce all the constituents of a food to one common 

 denomination so that the total nutritive value of 

 the food may be expressed by one figure, which is 

 commonly called the starch equivalent. 



