EXERCISES 21 



changed to soups so that they may be absorbed from the 

 digestive tract. These soaps are converted back to fats 

 after they have passed through the walls of the intestines 

 and are then taken into the circulation. The fat that is not 

 used to create heat or energy for external work is made into 

 fatty tissue which serves as a food reserve. 



Mineral Matter and Water. — Water is used all along the 

 digestive tract as a solvent. It is found in all parts of the 

 body, forming a necessary part of all tissues. Without 

 water there can be no circulation whatever. 



Mineral matter is taken up in solution all along the 

 digestive tract, and is carried by the circulation to all parts 

 of the body. Calcium or lime is used in building the skele- 

 ton. Phosphorus is used in the skeleton and also plays 

 an important part in the protoplasm and cells of the animal. 

 It is also found in protein compounds. Iron is found in the 

 blood and to its presence is due the power of the red corpus- 

 cles to carry oxygen. Magnesium is found in the bones 

 and in the blood, chlorine is necessary in protein digestion in 

 the stomach, and sodium and potassium are found in the 

 serum and the red corpuscles of the blood. 



EXERCISES 



1. Name a list of feeds high in starch. In oil. In protein. 

 In sugar. 



2. Classify the above feeds in order of the relative amounts 

 of these substances which they contain. 



3. Make a list of feeds of high water content and classify them 

 in order. 



HOME PROJECT 



Make a collection of all the feeds used on the home farm and 

 classify them in order of their most important content. 



