31 



(lestributioii than could be gained were thorn but the one kind 

 of spore. 



THE BLIGHTS (Perisporiticeac). 



These fungi have reproductive organs, much like the miedews 

 except that both kinds of spores are born 011 the surface of the 

 host plant. Leaves affected by the blight appear covered with 

 a grayish or whitish cobweb-like mass of threads or inycelia 

 interspersed here and there with small blackish specks. If one 

 of these specks were examined, with a compound microscope, it 

 would be seen to have a ball-like form, usually with many slender 

 projections coming from its surface. This ball-like body is the 

 resting' spore. When a mature resting spore is mashed under 

 the microscope it is seen to contain one or more sac-like bodies 

 filled with spores. These resting spores are provided with a 

 thick, heavy covering to protect the spores during the winter, 

 just as many seeds are provided with a 'hard shell for a like pur- 

 pose. 



The conidia of the blights are of the same color as the my- 

 celia and are produced earlier than the resting spores. They 

 are born 011 upright branches of the inycelia. 



The mycelia of the blights grow on the surface of the host 

 and send little branches or suckers down into the plant tissues 

 for nourishment and to insure a good hold upon the host. 



In the leaf spot fungi the spores are born on little upright 

 threads or in minute blackish receptacles clustered in variously 

 colored (usually whitish or brownish) spots on the surface of 

 the leaf. Most of these fungi are imperfect forms and have but 

 one kind of spore. 



THE SMUTS ( Ustilagineac). 



The mycelia of the smuts grows entirely within the tissues of 

 the host plant so that it is difficult to acertain whether or not 

 plants are affected until the spores appear. As the mycelia de- 

 velope a mass of them congregate at some place within the host 

 plant (generally at or near the flowers or fruit) and form the 

 spores. These when ripe show as a black powdery mass, as is 

 seen in the smutted ear of corn or head of wheat or barley. 

 The spores are very small, more or less rounded and black; when 



