182 ILLINOIS ACADEMY OF SCIENCE 



The spores of nearty 700 species fall within the limits 

 of 20 and 50 mu, and when we remember that few other 

 characters are of constant diagnostic value it appears 

 possible that with proper cultural studies a large number 

 of Septoria species may be united. In Saccardo's Sylloge 

 V. 22 a species is described (no. 4) having a spore length 

 ranging from 19-62 mu. If this be a single species, which 

 is entirely possible, then there appears to be no reason 

 why the 700 species mentioned could not with proper 

 methods of study be proven to belong to a small number 

 of specific types. Such a wholesale elimination of species 

 would probably not be acceptable to workers in this field, 

 but it seems to be fully as warranted in the light of our 

 knowledge to-day as the erection of myriads of species 

 based largely on the host plant which they parasitize. It 

 is to be hoped, however, that this tabulation will form 

 a stepping stone to a more complete knowledge of the 

 genus such as is obtained only by cultural and biological 

 studies and that it will serve to attract the general stud- 

 ent of pathology to this large and interesting genus, 

 about which we know so little. 



