244 THE CHEMISTRY OF CATTLE FEEDING 



It will be seen that as the quantity of straw increases from 

 o to maximum, the quantity of meal diminishes from maxi- 

 mum to o, and that the quantity of cake to be used with 

 each combination of the other two varies from minimum 

 (22*5) to maximum (36). 



The case of three foods may also be investigated by 

 graphic methods. They are, perhaps, too complicated to be 

 of much practical use as a means of solution, but as they help 

 to illuminate the subject they may be briefly described. 



In the diagram (Fig. 17) the points A, E, and E' occupy 

 the same relative positions as the cake, meal, and straw in the 



Protein 

 per cent. 

 25 



20 



15 



10 



Starch 



3O 35 4O 4-5 SO 55 6O 65 7O percent- 



FIG. 17. 



chart (p. 230). As before, the two parts, AD and DE, of the 

 line AE represent the proportions in which the meal and cake 

 must be taken when no straw is used. Similarly, the two parts, 

 AD' and D'E' represent the proportions in which the straw and 

 cake must be taken when no meal is used. Now, let the line 

 E'E be divided at any point e ; this point represents the 



