THE DISEASES OF PLANTS 



97 



You can also prove that mold is caused only by other 

 mold. To do this, put some wet bread in a wide-mouthed 

 bottle and plug the opening with cotton. Kill all the 

 spores that may be in this bottle by steaming one hour 



I 



FIG. 85. A HIGHLY MAGNIFIED SECTION OF DISEASED PEAR LEAF 

 Showing how spores are borne 



in the cooking steamer. This bread will not mold until 

 you allow live mold from the outside to enter. If, how- 

 ever, at any time you open the bottle and allow spores 

 to enter, or if you plant spores therein, and if there be 

 moisture enough, mold will immediately set in. 



