THE DISEASES OF PLANTS 



95 



this in the apple bin. So, too, many of the diseases found 

 in the field or garden are contagious. 



Sometimes, when the skin of a rotten apple has been 

 broken, you will find in the broken place a blue mold. It 

 was the mold that caused the apple to decay. This mold 

 is a living plant ; very small, to be sure, but nevertheless 

 a plant. Let us learn a little about molds, in order that 

 we may better understand 

 our apple and potato rots as 

 well as other plant diseases. 



If you cut a lemon and 

 let it stand for a day or two, 

 there will probably appear 

 a blue mold 

 like that you 

 have seen on 

 the surface of 

 canned fruit. 

 Bread also 

 sometimes 

 has this blue 

 mold ; at other 

 times it has a black mold/ and again a pink or yellow mold. 



These and all other molds are living plants. Instead of 

 seeds they produce many very small bodies that serve the 

 purpose of seeds and reproduce the mold. These are called 

 spores. Fig. 82 shows how they are borne on the parent 

 plant. 



It is also of great importance to decide whether by keep- 

 ing the spores away we may prevent mold. Possibly this 

 experiment will help us. Moisten a piece of bread, then 



FIG. 82. TANGLED THREADS OF BLUE MOLD 

 The single stalk on left shows how spores are borne 



