I2IO Rural School Leaflet 



The plant may use any one or all three of the groups, protein, carbo- 

 hydrates, and fat, as a form in which to store reserve food. Mainly, 

 however, reserve food is stored in the form of carbohydrates, of which 

 starch is the most common example. 



The body of a cow is built up from the food that she cats. It is com- 

 posed of the elements that also make up the plant body. These elements 

 form niunerous compounds, which may be grouped into the same live 

 groups into which the plant body, or the food of the cow, was separated : 

 water, ash, protein, carbohydrates, and fat. The chemical formula for 

 an animal fat may not be the same as for the particular vegetable fat that 

 was in the animal's food; this will hold true also for proteins and carbohy- 

 drates. In the animal body there are few compounds that are carbohy- 

 drate in nature. The plant, as already noted, stores its sur]jlus food mainly 

 as carbohydrate, with some protein and fat. The animal, on the other 

 hand, stores its excess food material as fat. The proportion of protein 

 in the animal body as a whole is large because the lean meat of the muscle 

 tissue is nearly pure protein. A good example of animal protein is the 

 albumen of an egg; another is the casein, or curd, of milk. There is no 

 common animal carbohydrate. Lard and tallow are common forms of 

 animal fat. 



What data there are show that in order to form the protein of the bod 3^ 

 the animal must have protein in the food Any excess of protein in the 

 food that is not needed to form body protein wiU be broken up. A part 

 of the protein carrying the nitrogen will be excreted, and the remainder 

 will be used as carbohydrate material. The protein of the body can have 

 no source except in the protein of the food. The carbohydrate material 

 in the body can have as its source, protein, carbohydrates, or fat in the 

 food. The fat in the bod}' may be manufactured from the protein, 

 carbohydrates, or fat. Therefore, to siunmarize, there must be a siiflficient 

 amount of protein in the food in order to keep up the necessary protein of 

 the body, but the fat or carbohydrates of the body may be derived from 

 any one of the groups — protein, carbohydrates, or fat — in the 

 food. 



The animal uses the water that it drinks and that it derives from its 

 food to keep up the supply in the body, much in the same way that the 

 plant uses water to help support the body by keeping the cells distended, 

 and as a transportation agent. The ash (mineral matter) taken into 

 the body forms the bones and furnishes the mineral matter that is present 

 in all the tissues. The protein makes up the muscle tissues of the body 

 and any nitrogenous matter in the other tissues. The carbohydrates are 

 used to furnish the energy for the muscles. Any excess of carbohydrates 

 may be transformed into fat and stored as reserve material. Fats in the 



