25 

 A crose \vall is formed •bet\veen the proirycelium and the stalk. The newly 

 forined conidia are like their parents but slightly smaller. The ability 



• 



of this fungus thus to form secondary conidia on proiryceliuin is important 

 in that it enables the first conidium when not on proper substratum, siinply 

 to form with sufficient moisture numerous new conidia, one of which at 

 least may possib]""- find its way to a rye plant or other grass host and so 

 further perpetuate the fungus. In its furtlier development the sphacelial 

 growth shows a decidefi tendency to spread itself upward before it has 

 attained its full df/velopment at the point of infection. IRhen this is 

 reached, as a ralfi, the ovary and often even the ajithers are covered with 

 the sphacelial growth. Occasionally parts of the ovary or anthers in the 

 midst of tlje fjingous growth or above it are preserved. Such is the case 

 when the ovary has been more or less developed before, the infection took 

 place, or when the spores, though they have been brong'ht to the ovary at an 

 early time,; because of the dry weather have been retarded in the formation 

 of the spJiiacelial stage. In such cases the formation of sclerotia may fail 

 entirely; and the rye kernel, in spite of the first stage of infection, may 

 yet be informed, though in an imperfect form. However, if the development of 

 such sppacelial stages be favored by moist weather sclerotia may still be 

 formed;, which are crowned by the more or less developed seed. It may also 

 happen that such a kernel retains a normal appearance bi^tt actually is a 

 sclerrotium,. the fungus having failed in its destructive %vork in the attainment 



of its full develppment. Such a partial development and preservation of the 



/ ^ 



starbh forming kernel tissue between the sclerotial tissues is a phenomenon 



of very rare occtirrence. 



