286 THE BOOK OF CORN 



botanists, led by sucji eminent investigaton, as Meyen, 

 Leveille, Tulasne brothers, De Bary, Kuehn, Fischer 

 von Waldheim and Brefeld, that the futility of such 

 methods for corn became apparent. Brefeld's publica- 

 tion in 189s completed our knowledge of the essential 

 features in the life history of the fungus, and for the 

 first time made a rational procedure possible. 



The habits of the fungus are readily described. 

 The spores, composing the black powder, are capable 

 of growth as soon as ripe but for the most part do not 

 grow until June, or later, of the year following. They 

 grow best in a nutrient solution, such as the drainings 

 from rich soil, or barnyard manure, and consequently 

 it is the smut masses that fall to the ground m the field 

 and are not wholly plowed under, or are distributed 

 in yards where cattle are fed dry stalks, that chiefly 

 furnish material for the spread of the disease. 



When the spores germinate they produce a white, 

 mold-like growth of limited extent, on which are borne 

 minute, colorless, secondary spores. If the fungous 

 filaments are submerged, the secondary spores are 

 formed sparingly, but when they develop in moist air 

 these spores are produced in the greatest profusion. 

 It is the aerial, secondary spores that are the direct 

 source of infection. They are carried about by air 

 currents, and falling upon the moist surface of any 

 part of the corn plant, not too mature, grow into the 

 plant and cause smut pustuhs. Under favorable con- 

 ditions it requires only twenty-four hours to produce 

 secondary spores after the black spores find a suitable 

 place in which to grow ; and after the secondary spores 

 strike the corn plant in growing condition but ten to 

 fourteen days are needed for a mass of smut to form, 

 which in a week longer will contain ripe spores. It 

 will be seen that the reproduction of the -fungus is very 

 rapid, three weeks being ample under favorable condi- 



