SECTION V. 



FOOD PRESERVATION AND DISEASES OF 

 PLANTS. 



CHAPTER XXV. 

 PRESERVATION OF FOODS. 



All organic matter whether of plant or animal origin 

 is subject to the attacks of living organisms which find 

 in it favorable conditions for growth. The changes in- 

 duced are, in the main, decomposition changes which 

 usually render the material unfit for use as food either 

 by human beings or animals. Food supplies that are to 

 be kept for any length of time must be treated so as to 

 prevent or retard the growth of micro-organisms. This 

 can be done in a variety of ways. 



Drying. One of the most common ways of preserv- 

 ing organic matter is to dry it, so that the water content 

 is reduced to a point where growth of micro-organisms 

 in or on the material is impossible. The bacteria can 

 grow only in the presence of considerable amounts of 

 moisture. Molds demand much less moisture for their 

 growth, hence many things may be protected from bac- 

 terial action and still be spoiled by the growth of molds. 



Fodders of all kinds are dried in the field before plac- 

 ing in the barn. If hay or dried forage is not thoroughly 

 dried, it will heat in the mow. The heat is produced by 



