USEFUL MOLDS 69 



Utility of Molds 



We never look upon molds as of any particular utility. 

 Nevertheless, when we study their relations in nature we 

 find that they are of the utmost importance. In the pro- 

 cesses which are going on in nature the molds form a very 

 important link, aiding in furnishing different kinds of liv- 

 ing beings with food. The woody part of trees contains 

 a large amount of material which cannot be used as food 

 by either plants or animals. Were it not for some agent 

 which brings this material into condition for subsequent 

 use by plants and animals, much of the food material of the 

 world would in time become stored away in the form of wood, 

 and the world would materially suffer as the result. But 

 the tree trunk does not remain a hard, solid mass very 

 long after it has fallen to the ground. It slowly softens 

 and decays, until eventually it assumes a condition in 

 which it can again be used for food by various animals 

 and plants. Insects, for example, feed upon the decaying 

 wood until, in time, the tree trunk is all consumed. In 

 this process a group of fungi similar to molds plays an 

 important part, for it is a mold-like mycelium growing 

 through the hard surface of the wood that begins the 

 softening necessary to make its utilization possible. With 

 this we are not particularly concerned, for the household 

 is not usually concerned in the decay of wood. Wood in 

 the household may occasionally decay, but it is such a rare 

 circumstance that the housewife pays little attention to it. 

 In recent years it has been learned that molds are valuable 

 commercially in the production of certain chemicals which 

 have industrial uses. A few food products, moreover, are 



