BACTERIA AND DISEASE 



383 



used in bread making and in the manufacture of alcohol 

 (see Chapter IV). 



683. Molds form a class of plants which may grow in 

 nearly all kinds of moist substances, and there induce a 

 kind of decay. They may usually be recognized by their 

 furry growth on the surface of the affected substance. 



Diagram of mold (X 200). 



a ball of spores above the surface. 

 b threads beneath the surface. 

 c spores beneath the surface. 



The plants themselves are usually a series of threads which 

 burrow beneath the surface. At intervals they send up 

 slender shoots which bear germ cells or spores. These 

 shoots constitute the fur which is usually called mold, but 

 many kinds form their spores beneath the surface. The 

 spores are microscopic in size, and can float in the air and 

 grow into mold plants when they fall upon a suitable soil. 

 Most forms grow only on dead material, but a few can 

 grow on living matter. The smut and rust on grain and 

 fruit are plants similar to molds. Ringworm is due to a 



