178 ILLINOIS ACADEMY OF SCIENCE 



were too small. This fact, cannot, however, be accepted 

 without thorough cultural studies of the genus. 



SPORE MEASUEEMENTS 



Attention is called to "inaccuracies" in the measure- 

 ment of spores best seen by a comparison of the number 

 of species having a given minimum length. Thus the 

 number of species having minimum lengths of 10, 20, 

 30, 40, 50, and 60 mu. is much greater than the number 

 with lengths of 15, 25, 35, 45, 55, etc., and these in turn 

 are more numerous than those with minimum lengths 

 of 14, 24, 34, 44, etc. This is also true if we consider 

 maximum measurements and suggests that the absolute 

 accuracy of these measurements is of questionable value. 

 It would thus appear to be more important to state the 

 length in an even number of microns, say 20 to 30, or 25 

 to 35 than to use figures such as 19 to 28, or 24 to 36 

 simply because these measurements happen to give the 

 range of the particular specimens examined. 



IMPORTANT SPECIFIC CHABACTEES 



Of the various specific characters commonly mentioned 

 in descriptions none seem more important than spore 

 length which, in Septoria, is to some extent correlated 

 with diameter and septation. As regards spore color, all 

 spores should be colorless, yet if we exaniine the tables 

 we find a number of species possessing spores with more 

 than permissable color. It is probable that these species 

 belong elsewhere. Ostiole measurements are thought to 

 be of value and deserve more attention than has formerly 

 been given them. The host is, under the present system 

 of determination, the factor most used in identification, 

 and its use affords the only convenient means of tracing 

 a species. It is to be regretted that more reliable means 

 are not at hand but until complete cultural studies are 

 made this means of tracing species will continue to be 

 important. 



EXPLANATION OF TABLES 



The following explanation of the tables is necessary: 

 Figures in column 1 represent the number of the fungus 



