254 



Proceedings of Indiana Academy of Science 



m = moderate in size. 



1 = large. 



1 = very large. 



In resistant varieties where flecks, necrotic or chlorotic areas are 

 produced, uredinia may or may not develop. This is denoted by the 

 numeral, sub 1, following the symbol. When both areas with and with- 

 out uredinia are found, the relative prevalence is denoted by writing 

 the more numerous first, ex., flF, denotes flecks without uredinia more 

 numerous than those with uredinia. 



The susceptibility as illustrated in Figure 5, A would be recorded thus, 

 Silc; B as sj; C as MJ; D as Silkim; E as sdg; F as kj; G as kikm; H as 

 kkim; I as f. 



Fix. 5. Types of susceptibility shown by rye to loalrust, I'urrinia dispcrsa. 



Such a system can be arranged to meet the needs of the individual 

 investigator. It should be emphasized that this is in no way a system of 

 classification of susceptibility. It is a rapid method for the recording of 

 symptoms from which the individual plant or the variety can later be 

 placed in its proper class of susceptibility when enough types have been 

 studied upon which to base such a classification. 



The relative quantity of uredinia pioduced has been denoted in our 

 notes by a corresponding segment of a circle surrounding the + mark 

 denoting infection. This, however, should be replaced by some more 

 suitable symbol. The number of plants infected out of the number in- 

 oculated is denoted by a fraction, the denominator giving the number 

 inoculated and the numerator those showing infection, a method used by 

 a number of investigators. 



