172 WALL'S MANUAL 



food. Starch, gum and sugar may be classed together", 

 since they serve a like purpose in sustaining animal 

 life. After undergoing digestion, they are all thrown 

 into the veins, where.they become a constituent part 

 of the blood, to be consumed during respiration, 

 They are not less essential to animal life than other 

 forms of diet ; yet, from their abundance in vegetable 

 products, they are not estimated at so high a value 

 as the protein and oily parts of plants. 



To estimate the value of the crop grown upon a 

 given piece of ground, we must not simply take into 

 account the relative quantities of these three kinds of 

 food contained in a given weight of the crop, but the 

 quantities contained in the whole product of the 

 land. A hundred pounds of potatoes contain only 

 about one- eighth as much protein matter as the same 

 weight of corn, one-ninth as much oily substance and 

 one-third as much starch, This shows that a given 

 weight of potatoes is far inferior in value to the same 

 weight of corn. 



But when we compare the products of an acre of 

 land cultivated in corn, with the product of an aero 

 cultivated in potatoes, the case stands differently. In 

 order to institute such a comparison, we may suppose 

 that an acre which would yield sixty bushels of corn, 

 or about 3500 pound of corn, would, if properly culti- 

 vated, yield four hundred bushels of potatoes, or 

 20,000 pounds. Thus we see that the feeding value of 

 the potatoes on one acre may greatly surpass corn. 



From the above principles and facts, w r e will find a 

 mixture of grain and hay, or fodder, as affording 

 probably the best combination of those properties 

 which adapt food to the use of work animals. We 



