158 LIFE ON THE FARM. 



decay. This is not due to the absence of bacteria, 

 but to conditions which prohibit their growth. 

 Some low, wet soils are of this nature. The soil 

 water holds acids in solution. These kill germs. 

 Such land generally becomes very productive when 

 well drained, for the washing out of the acids gives 

 the bacteria a chance to work. A good circula- 

 tion of air in the soil also increases their action. 



The decay of organic matter in general is caused 

 by the action of germs. Waste matter from 

 dwellings and stables readily decomposes when 

 moisture is present. Such matter is generally 

 piled in heaps to prevent loss of moisture by evap- 

 oration. Since decomposition produces heat, the 

 rate of decay can be determined roughly by the 

 temperature of the mass. 



Farmers are careful to harvest their crops and 

 store them away in a dry condition. Wet grain or 

 hay will so decay or "turn sour" in a day or two, 

 during very warm weather, as to become unfit for 

 animal food. It can then be used only as a fer- 

 tilizer. In some of these cases decay is due to the 

 growth of moulds and fungi, but the result is the 

 same as that produced by bacteria; namely, the 

 reduction of the substances into several elements 

 and compounds, their identity being destroyed. 



DECAY OF FRUITS, VEGETABLES AND MEATS. 



People have learned by experience that a wound 

 caused by cutting or breaking the skin is attended 



