PATHOGENICITY OF H. SATIVUM 



ii 



These comparisons are perhaps brought out more clearly by the 

 curves in Figure I, in which the data obtained from measuring the 

 different lots of spores have been plotted after grouping the measure- 

 ments into 10 micron classes. The lowest curve, representing 100 

 spores, very clearly does not give a true index of the lower extreme 

 of the total population. This explains why the mean obtained from 

 100 spores is too high. The three succeeding curves show that, as 

 the number of individuals increases, the curve gradually approaches 



Fig. i. Types of Curves Obtained from Measuring the Length of 100, 300, 500, and 1000 



Spores of Hclminthosporium sativum Produced on Potato Dextrose 



Agar at 32 C. 



