188 



PUKGI AND FUlfGICIDES 



mycelium, or vegetative portion of the fungus. As the 

 oats plant grows this mycelium also develops, taking 

 possession of all the new tissues of the host, and form- 

 ing within the head a mass of thick threads. These 

 threads eventually produce vast numbers of spores, so 

 using themselves up in the operation that they become 

 gelatinous, and finally altogether disappear, leaving 



g 



FIG. 78. SMUT SPORES GEllMIXATIKG. MAGNIFIED. 



nothing but the jjowdery mass of spores, which are 

 blown about to infect other plants, and thus begin anew 

 the cycle of existence. 



The smut mycelium usually produces no peculiar 

 effect upon its host-plant early in the season. Infested 

 plants are seldom distinguishable from healthy ones 



